Ramswaroop Kumawat

Difference between Intel i3 ,i5 & i7 core processors

2012-01-08T05:40:00.003+05:30

Hi, its for my all friends which wanted to know s difference in inlet's new processors

Difference Between Core i3, Core i5, Core i7

Difference between Core i3, Core i5 and Core i7

Intel will stop selling Core 2 Duo and Core 2 Quad in 2010. Core is the new range of Intel processors.

Core i3:
* Entry level processor.
* 2-4 Cores
* 4 Threads
* Hyper-Threading (efficient use of processor resources)
* 3-4 MB Catche
* 32 nm Silicon (less heat and energy)

Core i5:
* Mid range processor.
* 2-4 Cores
* 4 Threads
* Turbo Mode (turn off core if not used)
* Hyper-Threading (efficient use of processor resources)
* 3-8 MB Cathe
* 32-45 nm Silicon (less heat and energy)

Core i7:
* High end processor.
* 4 Cores
* 8 Threads
* Turbo Mode (turn off core if not used)
* Hyper-Threading (efficient use of processor resources)
* 4-8 MB Catche
* 32-45 nm Silicon (less heat and energy)

Tips for effective Active Directory Design

2010-10-03T20:11:00.001+05:30

Tips for effective Active Directory Design

1: Keep it simple

The first bit of advice is to keep things as simple as you can. Active Directory is designed to be flexible, and if offers numerous types of objects and components. But just because you can use something doesn't mean you should. Keeping your Active Directory as simple as possible will help improve overall efficiency, and it will make the troubleshooting process easier whenever problems arise.

2: Use the appropriate site topology

Although there is definitely something to be said for simplicity, you shouldn't shy away from creating more complex structures when it is appropriate. Larger networks will almost always require multiple Active Directory sites. The site topology should mirror your network topology. Portions of the network that are highly connected should fall within a single site. Site links should mirror WAN connections, with each physical facility that is separated by a WAN link encompassing a separate Active Directory site.

3: Use dedicated domain controllers

I have seen a lot of smaller organizations try to save a few bucks by configuring their domain controllers to pull double duty. For example, an organization might have a domain controller that also acts as a file server or as a mail server. Whenever possible, your domain controllers should run on dedicated servers (physical or virtual). Adding additional roles to a domain controller can affect the server's performance, reduce security, and complicate the process of backing up or restoring the server.

4: Have at least two DNS servers

Another way that smaller organizations sometimes try to economize is by having only a single DNS server. The problem with this is that Active Directory is totally dependent upon the DNS services. If you have a single DNS server, and that DNS server fails, Active Directory will cease to function.

5: Avoid putting all your eggs in one basket (virtualization)

One of the main reasons organizations uses multiple domain controllers is to provide a degree of fault tolerance in case one of the domain controllers fails. However, this redundancy is often circumvented by server virtualization. I often see organizations place all their virtualized domain controllers onto a single virtualization host server. So if that host server fails, all the domain controllers will go down with it. There is nothing wrong with virtualizing your domain controllers, but you should scatter the domain controllers across multiple host servers.

6: Don't neglect the FSMO roles (backups)

Although Windows 2000 and every subsequent version of Windows Server have supported the multimaster domain controller model, some domain controllers are more important than others. Domain controllers that are hosting Flexible Single Master Operations (FSMO) roles are critical to Active Directory health. Active Directory is designed so that if a domain controller that is hosting FSMO roles fails, AD can continue to function — for a while. Eventually though, a FSMO domain controller failure can be very disruptive.
I have heard some IT pros say that you don't have to back up every domain controller on the network because of the way Active Directory information is replicated between domain controllers. While there is some degree of truth in that statement, backing up FSMO role holders is critical.
I once had to assist with the recovery effort for an organization in which a domain controller had failed. Unfortunately, this domain controller held all of the FSMO roles and acted as the organization's only global catalog server and as the only DNS server. To make matters worse, there was no backup of the domain controller. We ended up having to rebuild Active Directory from scratch. This is an extreme example, but it shows how important domain controller backups can be.

7: Plan your domain structure and stick to it

Most organizations start out with a carefully orchestrated Active Directory architecture. As time goes on, however, Active Directory can evolve in a rather haphazard manner. To avoid this, I recommend planning in advance for eventual Active Directory growth. You may not be able to predict exactly how Active Directory will grow, but you can at least put some governance in place to dictate the structure that will be used when it does.

8: Have a management plan in place before you start setting up servers

Just as you need to plan your Active Directory structure up front, you also need to have a good management plan in place. Who will administrator Active Directory? Will one person or team take care of the entire thing or will management responsibilities be divided according to domain or organizational unit? These types of management decisions must be made before you actually begin setting up domain controllers.

9: Try to avoid making major logistical changes

Active Directory is designed to be extremely flexible, and it is possible to perform a major restructuring of it without downtime or data loss. Even so, I would recommend that you avoid restructuring your Active Directory if possible. I have seen more than one situation in which the restructuring process resulted in some Active Directory objects being corrupted, especially when moving objects between domain controllers running differing versions of Windows Server.

10: Place at least one global catalog server in each site

Finally, if you are operating an Active Directory consisting of multiple sites, make sure that each one has its own global catalog server. Otherwise, Active Directory clients will have to traverse WAN links to look up information from a global catalog.

HOW TO MAKE USB READ ONLY

2009-12-01T18:32:00.002+05:30

we know today there are main issue in IT world to secure their data there a lot business hub they can't disbale the usb but they also wants to secure data in pc here i am telling how to can make usb readbale through this method you can receive the data from usb mass storage device but you can't send data in usb that is fantastic way to secure your data.

1. Run Registry Editor (regedit)
.2. Navigate to the following registry

key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control3.

.3 Create a New Key named as StorageDevicePolicies.
4. Highlight StorageDevicePolicies, and then create a New DWORD (32-bit) Value name as WriteProtect.
5. Double click on WriteProtect, and set its value data to 1.Write Protect Removable USB DrivesOnce set, all users on the computer is now blocked and prevented from copying, transferring or writing any files, documents and data to the USB disk drives, without the need to restart or reboot computer. Any attempt to download or copy files to USB drive will return the following error message:The disk is write protected.The media is write-protected.Remove the write protection or use another disk.

Block Write Access to USB Removable Disk
To revert and remove the blocked write access to USB drivers, just delete the StorageDevicePolicies registry key, or delete the WriteProtect registry entry, or change the value data for WriteProtect to 0.

How to Install Portable Linux Into Usb Drive

2009-08-01T22:31:00.005+05:30

At one time or another, you would surely have felt the need for a portable Operating System that you could carry around with you and to help troubleshoot and backup your friends’ crashed PCs or just carry your complete Office with you. There are several Live CD based Linux Distributions(distros) where you just boot from it and enjoy the new OS. But what if you need your Data and settings to be remembered. A good alternative is to use a “LIVE USB” based OS.

Three things should be considered first.

Size of USB drive
Type of Distribution
Usage

Distros like Damn Small Linux and Puppy Linux will perform well in 256MB drives. Some OS’es section off a portion of your computer’s memory[RAM] and use that as a drive, in addition to the flash drive.

We will use an application called UNetbootin to install the Linux into the flash drive. We can let the program download a distro or select the image file(.iso) of an already downloaded distro. Download UNetbootin here: http://unetbootin.sourceforge.net/ and install it.

‘m using the Boxpup version of Puppy Linux as my distro.Get it from the official site here: http://www.puppylinux.org/ . Download for Boxpup version: http://www.puppylinux.org/downloads/puplets/boxpup

The downloaded file will be an .ISO file. The important thing to note here is to make sure that you have downloaded the file correctly. Thats why we’re going to verify the authenticity of the downloaded iso.So get the MD5 hash from the place you downloaded.it will be listed in the download page itself. Select the whole MD5 hash and copy it using ctrl-c.

Now install this MD5 hash checker called HashTab from here: http://beeblebrox.org/hashtab/. After you finish installing HashTab, right click the downloaded iso file, select properties.

MD5 checkers

You’ll see a tab called file hashes. Select the tab and wait for it to calculate the file hashes. Select MD5 and paste the MD5 hash, that you copied earlier, into the box that reads “Hash Comparison”. If your downloaded file in not tampered, you will see a green tick mark in the hash comparison box. If the downloaded iso file is tampered with or has been incorrectly downloaded, you will see a red cross. You should then attempt to re-download the file from another source.

As your iso file has been verified, it’s time to install the OS . Open UNetbootin and select the Diskimage Radio button and select the downloaded iso file. Please make sure the correct drive letter for your USB drive is selected below.
*It is very important to re-check this because a mistake will format one of the partitions in your hard disk.*

UNetBootin

Select Ok and let the program work for some time. After a few minutes you’ll see a dialog box asking to reboot. Click No. Save all your work, eject the USB drive but leave it in the USB port and restart the computer.

Now when your system is restarted, just boot your system with USB(change boot order frm BIOS). You’ll see the UNetbootin menu. Select Puppy.You’ll be asked a one-time set of questions to determine the setup of your computer.Thats it,you can customize your Linux as you want!

How to know where the Email Came From

2009-05-27T11:05:00.004+05:30

Today is we are facing a lot off issue in email scenario here I am telling you how we can trace a mail where the mail came from and we know is the mail is froad or not we know all this through e-mail header simple we can see header using web based mail and using outlook or other 3rd party e-mail client here i am telling you how to extract the header from outlook and how to trace it

for outlook simple right click on any mail and go in option a pop's window will open there you can see the internet header of a mail and below the method how to trace the mail:-

All Headers are in BLACK / Explanation to Each HEADER is in RED
HEADER :-Return-Path: vikasdhingra@speciality-india.com
EXPLAIN :-This is the Reply to ID: This means this is the sender (vikasdhingra@speciality-
indina.com
HEADER :-Received: from lx4.system3hosting.com (LHLO lx4.system3hosting.com)
(203.185.191.34) by lx4.system3hosting.com with LMTP; Sat, 4 Apr 2009 ,10:56:17
+0530 (IST)
EXPLAIN -:This is the mail received at System3 / mail server is called lx4.system3hosting.com
with the ip 203.185.191.34, it shows that we received the email on LX4 at
10:56AM IST on 4th April 2009.

This date is important to understand message analysis

HEADER :-Received: from localhost (localhost.localdomain [127.0.0.1])by
lx4.system3hosting.com (Postfix) with ESMTP id 89992119000D; Sat, 4 Apr 2009
10:56:17 +0530 (IST)
EXPLAIN :- Before mail is given to LX4, it is scanned by Anti virus / Anti-spam. This shows
that the mail was received by o Anti-spam on Lx4 (Local host) at 10:56:17

HEADER :-X-Virus-Scanned: amavisd-new at X-Spam-Flag: NO
EXPLAIN :- Antivirus Scanned the email and did not find any virus infection in this email. This
does not mean, the sender is not infected, it means any attachment in the email
does not have a virus.
HEADER :-X-Spam-Score: 0
EXPLAIN :-Anti-spam trusts the sender as he is a good friend, and also a customer, and hence
this email was given a spam score of (ZERO) 0.
HEADER :-X-Spam-Level: X-Spam-Status: No, score=x tagged_above=-10 required=6.6
tests=[]l
EXPLAIN :- No tests were done on the email here, hence you see tests=[], for a mail to be called
SPAM, it has to receive 6.6 Points, this mail received 0, hence it was not marked as
spam
HEADER :-Received: from lx4.system3hosting.com ([127.0.0.1]) by localhost
(lx4.system3hosting.com [127.0.0.1]) (amavisd-new, port 10024)with ESMTP id
5CCTkK0Y5zjq; Sat, 4 Apr 2009 10:56:17 +0530 (IST)
EXPLAIN :-this is the transfer from sender server to our anti-spam server

HEADER:-Received: from lx1.system3hosting.com (lx1.system3hosting.com [203.185.191.31])
by lx4.system3hosting.com (Postfix) with ESMTP id 0CCDED904ABfor
<hks@system3group.com>; Sat, 4 Apr 2009 10:56:17 +0530 (IST)

This is a very important line: You see here, that the email was sent using server
lx1.system3hosting.com (203.185.191.31) which is the server that hosts
the sender domain, and was sent to server lx4.system3hosting.com which hosts receiver domain. The email was for hks@system3group.com

HEADER:- Received: (qmail 5180 invoked by uid 511); 4 Apr 2009 10:50:49 +0530

EXPLAIN :-This line shows the sender mail server (in this case, lx1), the mail was processed by
QMAIL with an ID 511 on that server. The server processed this email at 10:50:49
IST that means it took roughly 6 minutes before the mail reached
hks@system3group.com

HEADER:-Received: from 122.173.243.137 by lx1.system3hosting.com (envelope-from
<vikasdhingra@speciality-india.com>, uid 510) with qmail-scanner-1.25-st-qms
Clear: RC:0(122.173.243.137):.Processed in 33.207305 secs); 04
Apr 2009 05:20:49 -0000
EXPLAIN :-This is again a very important line, this shows that vikasdhingra@speciality-
india.com had the IP Address 122.173.243.137 on his broadband / PC
depending on the connection when he submitted the mail to his SMTP Server
lx1.system3hosting.com. The envelope from means, the sender email id.
HEADER :-X-Anti-virus-MYDOMAIN-Mail-From: vikasdhingra@speciality-india.com via
lx1.system3hosting.com
EXPLAIN :-Anti-virus on Lx1 ran and saw this email as clean

HEADER:-X-Antivirus-MYDOMAIN: 1.25-st-qms (Clear:RC:0(122.173.243.137):. Processed in
33.207305 secs Process 5018)
EXPLAIN :- Q processor for Qmail run on LX1 and precessed this email in 33 Seconds. It took
this long, because it must have had a very long BCC List or the load on the server
was very high.
HEADER:-Received: from abts-north-dynamic-137.243.173.122.airtelbroadband.in (HELO
VikasPC2) (122.173.243.137) by lx1.system3hosting.com with SMTP; 4 Apr 2009
05:20:16 -0000
EXPLAIN :- This shows that the mail was received from 122.173.243.137 using VIKASPC2 by
Lx1 Server
HEADER :-Message-ID:
EXPLAIN :- This is one of the most important lines, that help us identify the PC. Some viruses
have the capability of using someone’s PC and using some one else
email id. The VikasPC2 will help us find the PC in the customer network
HEADER :-Reply-To: “Vikas Dhingra” <vikasdhingra@speciality-india.com>
EXPLAIN :- This shows the reply to field

HEADER:-From: “Vikas Dhingra” <vikasdhingra@speciality-india.com>
EXPLAIN :- This shows the From field
HEADER :-To: <”Undisclosed-Recipient:;”@lx4.system3hosting.com>

EXPLAIN :- This basically shows that the email was sent to a lot of people using BCC, clear
indication, that either the customer was doing BCC, or an virus infection was
sending these emails.

HEADER:-Subject: Best Pool Shot Ever by a Naked White Chick
EXPLAIN :- This is the Subject of the email

HEADER:-Date: Sat, 4 Apr 2009 11:08:21 +0530
EXPLAIN :- This is the Date on the PC of the customer, now this is where you see, that the
servers had a time of 10:56, while the customer PC had 11:08, now why this
difference, though both the server and Customer are in IST (+0530). The problem
is that desktops set the time manually, while servers are synchronized to an Atomic
Clock, hence we see this difference.

HEADER:-Organization: Specialty Merchandising Services
EXPLAIN :- When we configure email software, we put in the company name, this comes from
there
HEADER:-MIME-Version: 1.0 Content-Type: multipart/mixed; boundary=”—-
=_NextPart_000_014A_01C9B515.AA782130″

EXPLAIN :- This shows that The Content was MIME / Mixed, ie Attachment Type

HEADER:-X-Priority: 3

EXPLAIN :- This again means, Priority of the Email was Normal
HEADER :-X-MSMail-Priority: Normal
EXPLAIN :- The Priority of the mail (Microsoft also uses some properitary formats, and hence
we see the header X-MSMail-Priority) was set as NORMAL

HEADER :-X-Mailer: Microsoft Windows Mail 6.0.6001.18000
EXPLAIN :- This shows the mail software the customer was using. He was using Microsoft
Windows Mail (Which is the replacement of Outlook Express in Windows Vista) to
send this email.

HEADER :-x-mimeole: Produced By Microsoft MimeOLE V6.0.6001.18049
EXPLAIN :- This line means that the mail was generated using a MIMEOLE command,
typically this is done when you right click a file and send email to, the email is
automatically created, and attached to the mail. This can be done manually,
especially by viruses, as they pick up random files from the PC and send them to
people.

How To Test The Effectiveness Of Antivirus Software

2009-02-05T17:07:00.000+05:30

This is a critical quiz which anti-virus is effective and which anti-virus should i install
at our PC.
now i will showing the method test the effectiveness of a anti-virus software.You no need go to visit some dangerous websites for testing the software that has a risk lost your data,it is very simple,just copy and paste a file then save it.

This file are writing in character string,it does not contain any viral code.If the software detects this as a virus file,that means your anti-virus software worked and well protected.

1.Open your notepad,

2.Copy and paste below character string to your open notepad,

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

3.Select 'file' and click 'Save as',name this file as 123.com and save it.

4.If your anti-virus is correctly activated, it must then alert you instantaneously.

The grade of the alert are;

Grade 1 - After copy and paste the character string before save it,then giving alert.(excellent)

Grade 2 - After save it then giving alert or delete it.(very good)

Grade 3 - After save it and wait for a while then giving alert or delete it (good)

Grade 4 - Need to manually activate full scan then giving alert or delete it.(poor)

Grade 5 - Can't detect. (need to change your anti-virus software)

Maybe you can share with us what is the grade of your anti-virus software.

How to protect your computer from hackers, spyware and viruses

2009-01-10T12:32:00.003+05:30

I recently made a trip there and since I’m in the IT field, she asked me to take a look at her computer since it was acting “funny”. The “funny” act was that the computer would automatically restart whenever you tried to install ANY software onto it or download any program from the Internet. First thing I noticed was that there was no anti-virus software installed on the computer, so my first goal was to install AVG anti-virus and check for viruses. But of course, the virus that was already on the computer would not let me install or download anything! Smart virus! To make a long story short (and I mean a LONG story), there were a lot viruses on the computer and a lot instances of spyware. I have never even heard of such a ludicrous number of viruses on a computer before!
Most of the viruses on the computer were hidden in files that had been downloaded off the Internet: songs, videos, and movies. I was amazingly surprised that the computer lasted for 2 years with that many viruses! So I gave my dear cousin a serious lesson in how to protect her computer from the dangers of the Internet and I will go through them here for anyone else who might be interested!
This is by no means a comprehensive list, so if you have any suggestions, please feel free to comment and I’ll add them on!
1. Install Anti-Virus Software -

This should not even have to be listed, if you don’t have anti-virus software installed, you’re asking for trouble! And if your reason for not installing anti-virus software is because it’s too expensive, then that can reason can be shot down because there are several free anti-virus programs out there that are considered better than commercial software packages. Here are two of the most popular ones:
AVG Anti-Virus - Very good and completely free.
Avast Anti-Virus - Almost on par with AVG.
Kaspersky Anti-Virus - Not free, but one of the best detection rates.

2. Update All Software -

Installing an anti-virus program by itself is not enough. There are hundreds of new threats that are found daily and the anti-virus programs release updates regularly to combat the new threats. Make sure you anti-virus program is set to update automatically so that you don’t have to rely on your memory to do it. Also, this goes for all the software on your computer. The most important software to keep up to date is your Windows operating system. It is essential to have Automatic Updates turned on and set to download and install updates automatically.

3. Install only Trusted Software -

If you’re not sure what a piece of software does from it’s name, then don’t install it. Also, don’t install anything you didn’t intend to install in the first place. Sometimes programs will ask you to install other programs during the install of the first application. Be careful of that because it’s usually spyware. Install software from big names sites only, such as Microsoft or Adobe.

4. Avoid P2P File Sharing Software -

If used with great caution, P2P software is quite useful for movies, songs and software, but if you’re not very technically savvy, you might end up downloading a song that has a keystroke logger attached to it that will send anything you type to some other computer over the Internet. It’s almost impossible to tell that this is occurring unless your anti-virus or anti-spyware programs pick it up in their scans.
5. Delete Unknown Emails -

If you receive emails from random people’s names, do not bother to open the email, just delete it. If you have any doubts after reading the name and the subject, it’s probably not someone you know. Never download or open attachments unless you are sure it’s from someone you know. Give the person a call quickly and ask them if you’re not sure. Most large companies that you create online accounts with will not send you attachments unless you specifically ask for them through their web site. Also, be wary of any emails from sites pretending to be banks, auction sites, etc asking for you to verify bank account info or address info. No bank ever does that.

6. Do not click on Ads -

Avoid clicking on ads if you can. Especially those ads where something is flying around and if you shoot the duck, you win some prize! Ads have become more sophisticated in that they try to make the ad interactive so that you’ll be tempted to play it like a game.

7. Run Virus Scans Regularly -

If you’re not in the mood to scan every day, at least run a scan once a week. Actually, setup a schedule for your computer in your anti-virus software to run a scan late at night or whenever you don’t use your computer and that way you won’t be bothered with a slow computer.

8. Be careful what you attach to your computer -

This is a more common way to transfer viruses than you might think. Everyone now has a USB flash stick that they carry around on their key chains, ready to snap into any computer. But who knows what your viruses are on your friends computers and what accidentally got transferred to their USB stick. A lot of virus programs will auto launch right when the USB stick is put into the computer, so you don’t even have to open or download any of the files to be infected.

9. Avoid Shady Web Sites -

If you need to look at porn, then make sure you do it in a virtual environment. You are DEFINITELY going to get some virus or spyware if you browse porn sites on your computer. Virtualization basically allows you to run programs like Internet Explorer in a virtual environment that does not effect your current operating system. If you want to find out more, search for “Virtual PC” or “VM Ware” in Google. Otherwise, simply avoid going to shady web sites!

10. Turn On or Install a Firewall -

If you’re running Windows XP, make sure Windows Firewall is turned on. A firewall prevents hackers from gaining access to your computer by limiting the number of ports that are open to the public. Also, when buying a wireless router, make sure it has a built in firewall. Having a software and hardware firewall is better than just having one or the other.

11. Secure Your Wireless Network -

Most wireless routers are set to no security when you install them. Be sure to log into the router and at least set the basic security that requires a password. There are stronger encryption options, but if you don’t understand those, then simply set a password on the router, otherwise anyone can connect to your home network and access everything.

12. Use a Complex Password for Login -

This means that you should already have a password to login to your computer. Not having a password at all is not a good idea. Create a password for all user accounts and make sure it’s complex. Complex means it should have numbers, upper case characters, lower case characters, and symbols. This makes it way more difficult for a hacker to get into your computer.

Install Active Directory Domain Services via Server Manager

2008-10-24T11:28:00.000+05:30

Requirements for Active Directory Domain Services

Let’s go through some of the requirements for a fresh install of Active Directory Domain Services. Some of these will be required to be done before hand; others as noted can be done during the install:

Install Windows Server 2008
Configure TCP/IP and DNS networking configurations
The disk drives that store SYSVOL must be on a local drive configured NTFS
Active Directory requires DNS to be installed in the network. If it is not already installed you can specify DNS server to be installed during the Active Directory Domain Services installation.

Once you verify that these requirements have been met we can get started.

Install Active Directory Domain Services via Server Manager

For the first example let’s start by installing Active Directory through Server Manager. This is the most straight forward way, as a wizard will guide you through the steps necessary.

1. Start Server Manager.

2. Select Roles in the left pane, then click on Add Roles in the center console.

3. Depending on whether you checked off to skip the Before You Begin page while installing another service, you will now see warning pages telling you to make sure you have strong security, static IP, and latest patches before adding roles to your server.

If you get this page, then just click Next.

4. In the Select Server Roles window we are going to place a check next to Active Directory Domain Services and click Next.

5. The information page on Active Directory Domain Services will give the following warnings, which after reading, you should click Next:

Install a minimum of two Domain Controllers to provide redundancy against server outage (which would prevent users from logging in with only one)
AD DS requires DNS which if not installed you will be prompted for
After installing AD DS you must run dcpromo.exe to upgrade to a fully functional domain controller
Installing AD DS will also install DFS Namespaces, DFS Replication, and Filer Replication services which are required by Directory Service

6. The Confirm Installation Selections screen will show you some information messages and warn that the server may need to be restarted after installation.

Review the information and then click Next.

7. The Installation Results screen will hopefully show Installation Succeeded, and an additional warning about running dcpromo.exe (I think they really want us to run dcpromo).

After you review the, click Close.

8. After the Installation Wizard closes you will see that server manager is showing that Active Directory Domain Services is still not running. This is because we have not run dcpromo yet.

9. Click on the Start button, type dcpromo.exe in the search box and either hit Enter or click on the search result.

10. The Active Directory Domain Services Installation Wizard will now start.

There are links to more information if you want to learn a bit more you can follow them or you can go ahead and click Use advanced mode installation and then click Next.

11. The next screen warns about some operating system compatibility with some older clients.

For more information you can view the support documentation from Microsoft and after you have read through it go ahead and click Next.

12. Next is the Choose Deployment Configuration screen and you can choose to add a domain to an existing forest or create a forest from scratch.

Choose Create a new domain in a new forest and click Next.

13. The Name the Forest Root Domain wants you to name the root domain of the forest you are creating.

For the purposes of this test we will create ADExample.com. After typing that go ahead and click Next.

14. The wizard will test to see if that name has been used, after a few seconds you will then be asked for the NetBios name for the domain.

In this case I will leave the default in place of ADEXAMPLE, and then click Next.

15. The next screen is the Set Forest Functional Level that allows you to choose the function level of the forest.

Since this is a fresh install and a new forest with no additional prior version domains to worry about I am going to select Windows Server 2008. If you did have other domain controllers at earlier versions or had a need to have Windows 2000 or 2003 domain controllers (because of Exchange for example), then you should select the appropriate function level.

Select Windows Server 2008 and then click Next.

16. Now we come to the Additional Domain Controller Options where you can select to install a DNS server, which is recommended on the first domain controller.

If this was not the first domain controller you would have the options of installing Global Catalog and/or setting this as a Read-only Domain Controller. Since it is the first domain controller, Global Catalog is mandatory, and a RDOC controller is not an available option.

Let’s install the DNS Server by placing a check next to it and clicking Next.

17. You will get a warning window about delegation for this DNS server cannot be created, but since this is the first DNS server you can just click Yes and ignore this warning.

18. Next you can choose to place the files that are necessary for Active Directory, including the Database, Log Files, and SYSVOL.

It is recommended to place the log files and database on a separate volume for performance and recoverability. You can just leave the defaults though and click Next.

19. Now choose a password for Directory Services Restore Mode that is different than the domain password. Type your password and confirm it before hitting Next.

Note: You should use a STRONG password for this and will be warned if it doesn’t meet criteria.

20. Next you will see a summary of all the options you have went through in the wizard.

If you plan on creating more domain controllers with the same settings hit the Export settings … button to save off a txt copy of the settings to use in an answer file for a scripted install. After exporting and reviewing settings click on Next.

21. Now the installation will start including the DNS server option if selected. You will notice a box to Reboot on completion that you can check to reboot soon as everything is installed (A reboot is required you can do it manually or use this function to do it automatically).

NOTE: This can be from a few minutes to several hours depending on different factors.

Confirming Active Directory Domain Services Install

When you reboot you will be asked to login to the domain, and be able to open Active Directory Users and Computers from the Administrative menu.

When you do you will see the domain ADExample.com and be able to manage the domain.

You have now successfully installed Active Directory Domain Services and the first Domain Controller.

How to Disable USB Port on PC

2008-09-19T10:44:00.000+05:30

many IT managers USB port connectivity can still pose a large threat to company security. One quick down-and-dirty method is disabling the read and write from any system USB port. This can be done through a quick registry edit.
Here is the full Microsoft article explaining how to disable a USB port (link). Note: This is a registry edit so be sure to backup your registry first and know how to restore it in case something terrible happens.

To disable the access to USB port, in windows XP and 2000:

1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate, and then click the following registry

key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor4.

In the right pane, double-click Start.

4. In the Value data box, type

5, click Hexadecimal (if it is not already selected), and then click OK.

6. Quit Registry Editor.
To re-enable a disabled port:
1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate, and then click the following registry

key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

4. In the right pane, double-click Start.

5. In the Value data box, type 3, click Hexadecimal (if it is not already selected), and then click

OK.

6. Quit Registry Editor.

Next Genetration's Wireless solution(WiMax )

2008-06-04T11:00:00.000+05:30

WiMax is the industry term for a long-range wireless networking standard. WiMax technology has the potential to deliver high-speed Internet access to rural areas and other locations not serviced by cable or DSL technology. WiMax also offers an alternative to satellite Internet services.
WiMax technology is based on the IEEE 802.16 WAN communications standard. WiMax signals can function over a distance of several miles / kilometers. Data rates for WiMax can reach up to 75 megabits per second (Mb/s). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz.
WiMax equipment exists in two forms. WiMax base stations are installed by service providers to deploy the technology in a coverage area. WiMax antennas must be installed at the home or other receiving location. As WiMax evolves, these antennas will change from being mounted outdoors, to smaller varieties set up indoors, and then finally to built-in versions integrated inside mobile computers. Similar to other types of Internet access, consumers will subscribe and pay a recurring fee to connect to the Internet via WiMax.
WiMax is developed by an industry consortium, overseen by a group called the WiMax Forum. The WiMax Forum certifies WiMax equipment to ensure it meets the technology standards. WiMax is not a replacement for Wi-Fi hotspot and home networking technologies primarily for cost reasons.

some pics of SARIKA OR SILISHED TRIP

2008-04-28T13:35:00.000+05:30

Side Effects of Tata's Nano Car

2008-01-24T11:20:00.000+05:30

Thoughts from great personalities....

2007-12-18T15:13:00.000+05:30

Windows vista Home Basic Troubleshooting & Tips.

2007-12-10T10:50:00.000+05:30

Disable large icons problem:-Right click on the Start Button and select Properties.Click on the Customize button.Scroll to the bottom of the list and remove the check from Use large icons.You can now also increase the number of recently run programs in vista that are displayed to something larger than 9.Hit OK when you are finished.

windows Vista adiitional clock:-

Windows Vista, you can add additional clocks to the system tray. Click the clock, and then click Date and Time Settings. Click the Additional Clocks tab. You can add one or two additional clocks to the tray and select their time zones.Here is more Windows Vista Features

Vista's word and notepad document more secure:-

You can create XML documents, which are more secure than regular text files or even word processor docs. Just create a document in a word processor, print(not print out ) it via the options menu, and select the XPS printer.Thats it u have secure document.

Vista Home Basic Internet Explorer Problem:-

If you’re annoyed by Internet Explorer’s incessant barking that you’ve lowered your security settings , launch “gpedit.msc” from either the Run command or Start Search field, navigate through Local Computer Policy / Computer Configuration / Administrative Templates / Windows Vista Components / Internet Explorer. In the rightmost pane, double-click “Turn off the Security Settings Check feature” and set it to Enabled.

Windows Vista Task manager for troubleshooting:-

The Windows Task Manager gives you a lot more troubleshooting information in Vista.Click ctr+alt+del, Flip to the Processes tab, and in the View menu, click “Select Columns” and add Description, Command Line, and Image Path Name. Moreover, when you right-click a process, you can select either “Go to Service(s)” or “Open File Location.” These are all long overdue options.

Displaying Run on the vista Desktop:-

You can create a shortcut for the Run command on your desktopFrom the Start Menu, go to All Programs / AccessoriesDrag a shortcut for Run to the desktop.

vista Displaying Run on the Start Menu:-

By default, Run is not shown when you open the Start Menu.To enable this:Right click on the taskbarSelect PropertiesClick on the Start Menu tabClick on the Customize buttonScroll down and check Run (it's about 2/3's of the way towards the bottom.

Windows Vista Tips to allow Network access without password:-

In windows vista you can access computer locally without password but it does not permit to access other network computer to access it without password. But you can change this default setting.Go to run and type there “gpedit.msc”.It will open group policy now go to computer configuration- vista setting- security setting-local policies(here you can set many local policy as per your security demands).-security options.Now you need to find and disable following optionsDouble click on accounts: limit local account use of blank password to console login only.There are lots of debate about Windows Vista Requirements for hardare.

Windows vista tips to add Internet Explore7 Icon on desktop:-

In windows vista you can not find IE7 icon on desktop by default.But you can add it by registry editing.Take back up of registry before making any changesGo to run and type regeditAnd expand to Hkey-current user> software >Microsoft> windows > current version> explorer>HideDesktopIcons>NewStartPanel. And give value” {871C5380-42A0-1069-A2EA-08002B30309D}"=dword:00000000.If you not find HideDesktopIcons then create new dword and give value as above.Now close regedit and restart the computer.

Windows Vista Tips for Resizing hard disk Partitions:-

Before windows vista each Microsoft operating system require third party software to resize partition like c: or d:/.But windows vista has inbuilt features to do this.Select my computer and right click itClicks on manage option and then select Disk Management.Now select partition on which you want to make changes like increase the size of partition or decrease the size of partition.Note: this will not delete your data on that partition but it is good if you take back up before doing such changes.

Access Denied error in windows vista:-
When you trying to access some windows folder like document and setting you may get error message that “access denied”. you need to change ownership of this folder. So open properties by right click on it. In security button select advance tab and click edit button. Now change ownership to your account by highlighting your account and also select replace ownership to sub containers and apply changes.

Rare picture of Indian Revolution

2007-09-14T13:10:00.000+05:30

Ramswaroop Kumawat

IT Team leader of

Airarabia,Track-india,IDFS

from System3 net technology

Bluetooth

2007-09-08T11:15:00.000+05:30

Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group.
Contents[hide]
1 Uses
1.1 Bluetooth profiles
1.2 List of applications
1.3 Bluetooth vs. Wi-Fi in networking
1.3.1 Bluetooth
1.3.2 Wi-Fi
2 Computer requirements
2.1 Operating system support
3 Specifications and features
3.1 Bluetooth 1.0 and 1.0B
3.2 Bluetooth 1.1
3.3 Bluetooth 1.2
3.4 Bluetooth 2.0
3.5 Bluetooth 2.1
3.6 Future of Bluetooth
3.6.1 Bluetooth 3.0
3.6.2 High speed Bluetooth
3.6.3 Ultra Low Power Bluetooth
4 Technical information
4.1 Communication and connection
4.2 Setting up connections
4.3 Pairing
4.4 Air interface
4.5 Security
5 Social concerns
5.1 Security concerns
5.2 Health concerns
6 Origin of the name and the logo
7 Bluetooth Consortium
8 See also
9 References
10 External links
10.1 Official
10.2 Other
//

[edit] Uses

A typical Bluetooth mobile phone headset
Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meter)[1] based on low-cost transceiver microchips in each device.
Bluetooth lets these devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, as long as the received transmission is powerful enough.
Class
Maximum Permitted Power(mW/dBm)
Range(approximate)
Class 1
100 mW (20 dBm)
~100 meters
Class 2
2.5 mW (4 dBm)
~10 meters
Class 3
1 mW (0 dBm)
~1 meter
It has to be noted that in most cases the effective range of class 2 devices is extended if they connect to a class 1 transceiver, compared to pure class 2 network. This is accomplished by higher sensitivity and transmitter power of the Class 1 device. The higher transmitter power of Class 1 device allows higher power to be received by the Class 2 device. Furthermore, higher sensitivity of Class 1 device allows reception of much lower transmitted power of the Class 2 devices. Thus, allowing operation of Class 2 devices at much higher distances.

[edit] Bluetooth profiles
Main article: Bluetooth profile
In order to use Bluetooth, a device must be compatible with certain Bluetooth profiles. These define the possible applications and uses.

[edit] List of applications
More prevalent applications of Bluetooth include:
Wireless control of and communication between a mobile phone and a hands-free headset or car kit. This was one of the earliest applications to become popular.
Wireless networking between PCs in a confined space and where little bandwidth is required.
Wireless communications with PC input and output devices, the most common being the mouse, keyboard and printer.
Transfer of files between devices with OBEX.
Transfer of contact details, calendar appointments, and reminders between devices with OBEX.
Replacement of traditional wired serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices.
For controls where infrared was traditionally used.
Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices.
Seventh-generation game consoles—Nintendo Wii [2], Sony PlayStation 3—use Bluetooth for their respective wireless controllers.
Receiving commercial advertisements ("spam") via a kiosk, e.g. at a movie theatre or lobby
One uncommon but amusing additional use is the remote management of sex toys (see Bluedildonics, Teledildonics [3][4][5][6])

[edit] Bluetooth vs. Wi-Fi in networking
Bluetooth and Wi-Fi have slightly different applications in today's offices, homes, and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers. Both are versions of unlicensed spread spectrum technology.

[edit] Bluetooth
Bluetooth is implemented in a variety of new products such as phones, printers, modems, and headsets. Bluetooth is acceptable for situations when two or more devices are in proximity to each other and don't require high bandwidth. Bluetooth is most commonly used with phones and hand-held computing devices, either using a Bluetooth headset or transferring files from phones/PDAs to computers.
Bluetooth also simplifies the discovery and setup of services. Bluetooth devices advertise all services they provide. This makes the utility of the service that much more accessible, without the need to worry about network addresses, permissions and all the other considerations that go with typical networks.

[edit] Wi-Fi
Wi-Fi is more analogous to the traditional Ethernet network and requires configuration to set up shared resources, transmit files, set up audio links (for example, headsets and hands-free devices). It uses the same radio frequencies as Bluetooth, but with higher power output resulting in a stronger connection. Wi-Fi is sometimes called "wireless Ethernet." Although this description is inaccurate, it provides an indication of its relative strengths and weaknesses. Wi-Fi requires more setup, but is better suited for operating full-scale networks because it enables a faster connection, better range from the base station, and better security than Bluetooth.
One method for comparing the efficiency of wireless transmission protocols such as Bluetooth and Wi-Fi is spatial capacity, or bits per second per square meter.

[edit] Computer requirements

A typical Bluetooth USB dongle (BCM2045A), shown here next to a metric ruler

An internal notebook Bluetooth card (14×36×4 mm)
A personal computer must have a Bluetooth adapter in order to be able to communicate with other Bluetooth devices (such as mobile phones, mice and keyboards).While some portable computers and fewer desktop computers already contain an internal Bluetooth adapter, most PCs require an external USB Bluetooth dongle. Most Macs come with built-in Bluetooth adapters.
Unlike its predecessor, IrDA, in which each device requires a separate dongle, multiple Bluetooth devices can communicate with a computer over a single dongle.

[edit] Operating system support
For more details on this topic, see Bluetooth stack.
Linux provides two Bluetooth stacks, with the BlueZ stack included with most Linux kernels. It was originally developed by Qualcomm and Affix. BlueZ supports all core Bluetooth protocols and layers.
Of Microsoft platforms, Windows XP Service Pack 2 and later releases have native support for Bluetooth. Previous versions required the users to install their Bluetooth adapter's own drivers, which was not directly supported by Microsoft.[7] Microsoft's own Bluetooth dongles (that are packaged with their Bluetooth computer devices) have no external drivers and thus require at least Windows XP Service Pack 2.
Mac OS X has supported Bluetooth since version 10.2 released in 2002. [8]

[edit] Specifications and features
The Bluetooth specification was developed in 1994 by Sven Mattisson and Jaap Haartsen, who were working for Ericsson Mobile Platforms in Lund, Sweden.[9] The specification is based on frequency-hopping spread spectrum technology.
The specifications were formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1998. Today it has over 7000 companies worldwide. It was established by Ericsson, Sony Ericsson, IBM, Intel, Toshiba, and Nokia, and later joined by many other companies. Bluetooth is also known as IEEE 802.15.1.

[edit] Bluetooth 1.0 and 1.0B
Versions 1.0 and 1.0B had many problems, and manufacturers had difficulties making their products interoperable. Versions 1.0 and 1.0B also had mandatory Bluetooth hardware device address (BD_ADDR) transmission in the Connecting process, rendering anonymity impossible at a protocol level, which was a major setback for services planned to be used in Bluetooth environments, such as Consumerium.

[edit] Bluetooth 1.1
Many errors found in the 1.0B specifications were fixed.
Added support for non-encrypted channels.
Received Signal Strength Indicator (RSSI).

[edit] Bluetooth 1.2
This version is backward-compatible with 1.1 and the major enhancements include the following:
Faster Connection and Discovery
Adaptive frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence.
Higher transmission speeds in practice, up to 721 kbit/s, as in 1.1.
Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets.
Host Controller Interface (HCI) support for three-wire UART.

[edit] Bluetooth 2.0
This version, specified in November 2004, is backward-compatible with 1.1. The main enhancement is the introduction of an enhanced data rate (EDR) of 3.0 Mbit/s. This has the following effects:[10]
Three times faster transmission speed—up to 10 times in certain cases (up to 2.1 Mbit/s).
Lower power consumption through a reduced duty cycle.
Simplification of multi-link scenarios due to more available bandwidth.
Further improved (bit error rate) performance.

[edit] Bluetooth 2.1
Bluetooth Core Specification Version 2.1 , is fully backward-compatible with 1.1, and was adopted by the Bluetooth SIG on August 1, 2007.[11] This specification includes the following features:
Extended inquiry response: provides more information during the inquiry procedure to allow better filtering of devices before connection. This information includes the name of the device, a list of services the device supports, as well as other information like the time of day, and pairing information.
Sniff subrating: reduces the power consumption when devices are in the sniff low-power mode, especially on links with asymmetric data flows. Human interface devices (HID) are expected to benefit the most, with mouse and keyboard devices increasing the battery life from 3 to 10 times those currently used.
Encryption Pause Resume: enables an encryption key to be refreshed, enabling much stronger encryption for connections that stay up for longer than 23.3 hours (one Bluetooth day).
Secure Simple Pairing: radically improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. It is expected that this feature will significantly increase the use of Bluetooth.[12]
NFC cooperation: automatic creation of secure Bluetooth connections when NFC radio interface is also available. For example, a headset should be paired with a Bluetooth 2.1 phone including NFC just by bringing the two devices close to each other (a few centimeters). Another example is automatic uploading of photos from a mobile phone or camera to a digital picture frame just by bringing the phone or camera close to the frame [13] [14].

[edit] Future of Bluetooth
Broadcast Channel: enables Bluetooth information points. This will drive the adoption of Bluetooth into cell phones, and enable advertising models based around users pulling information from the information points, and not based around the object push model that is used in a limited way today.
Topology Management: enables the automatic configuration of the piconet topologies especially in scatternet situations that are becoming more common today. This should all be invisible to the users of the technology, while also making the technology just work.
Alternate MAC PHY: enables the use of alternative MAC and PHY's for transporting Bluetooth profile data. The Bluetooth Radio will still be used for device discovery, initial connection and profile configuration, however when lots of data needs to be sent, the high speed alternate MAC PHY's will be used to transport the data. This means that the proven low power connection models of Bluetooth are used when the system is idle, and the low power per bit radios are used when lots of data needs to be sent.
QoS improvements: enable audio and video data to be transmitted at a higher quality, especially when best effort traffic is being transmitted in the same piconet.
Bluetooth technology already plays a part in the rising Voice over IP (VOIP) scene, with Bluetooth headsets being used as wireless extensions to the PC audio system. As VOIP becomes more popular, and more suitable for general home or office users than wired phone lines, Bluetooth may be used in cordless handsets, with a base station connected to the Internet link.

[edit] Bluetooth 3.0
The next version of Bluetooth after v2.1, code-named Seattle, that will be called Bluetooth 3.0, has many of the same features, but is most notable for plans to adopt ultra-wideband (UWB) radio technology. This will allow Bluetooth use over UWB radio, enabling very fast data transfers of up to 480 Mbit/s, while building on the very low-power idle modes of Bluetooth.

[edit] High speed Bluetooth
On 28 March 2006, the Bluetooth Special Interest Group announced its selection of the WiMedia Alliance Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) version of UWB for integration with current Bluetooth wireless technology.
UWB integration will create a version of Bluetooth wireless technology with a high-speed/high-data-rate option. This new version of Bluetooth technology will meet the high-speed demands of synchronizing and transferring large amounts of data, as well as enabling high-quality video and audio applications for portable devices, multi-media projectors and television sets, and wireless VOIP.
At the same time, Bluetooth technology will continue catering to the needs of very low power applications such as mice, keyboards, and mono headsets, enabling devices to select the most appropriate physical radio for the application requirements, thereby offering the best of both worlds.
The Draft High Speed Bluetooth Specification is available at the Bluetooth website.

[edit] Ultra Low Power Bluetooth
On June 12, 2007, Nokia and Bluetooth SIG announced that Wibree will be a part of the Bluetooth specification as an ultra low power Bluetooth technology[15]. Expected use cases include watches displaying Caller ID information, sports sensors monitoring your heart rate during exercise, as well as medical devices. The Medical Devices Working Group is also creating a medical devices profile and associated protocols to enable this market.

[edit] Technical information

[edit] Communication and connection
A master Bluetooth device can communicate with up to seven devices. This network group of up to eight devices is called a piconet.
A piconet is an ad-hoc computer network, using Bluetooth technology protocols to allow one master device to interconnect with up to seven active devices. Up to 255 further devices can be inactive, or parked, which the master device can bring into active status at any time.
At any given time, data can be transferred between the master and one other device, however, the devices can switch roles and the slave can become the master at any time. The master switches rapidly from one device to another in a round-robin fashion. (Simultaneous transmission from the master to multiple other devices is possible, but not used much.)
Bluetooth specification allows connecting two or more piconets together to form a scatternet, with some devices acting as a bridge by simultaneously playing the master role and the slave role in one piconet. These devices are planned for 2007.

[edit] Setting up connections
Any Bluetooth device will transmit the following sets of information on demand:
Device name.
Device class.
List of services.
Technical information, for example, device features, manufacturer, Bluetooth specification, clock offset.
Any device may perform an inquiry to find other devices to which to connect, and any device can be configured to respond to such inquiries. However, if the device trying to connect knows the address of the device, it always responds to direct connection requests and transmits the information shown in the list above if requested. Use of device services may require pairing or acceptance by its owner, but the connection itself can be started by any device and held until it goes out of range. Some devices can be connected to only one device at a time, and connecting to them prevents them from connecting to other devices and appearing in inquiries until they disconnect from the other device.
Every device has a unique 48-bit address. However these addresses are generally not shown in inquiries. Instead, friendly Bluetooth names are used, which can be set by the user. This name appears when another user scans for devices and in lists of paired devices.
Most phones have the Bluetooth name set to the manufacturer and model of the phone by default. Most phones and laptops show only the Bluetooth names and special programs that are required to get additional information about remote devices. This can be confusing as, for example, there could be several phones in range named T610 (see Bluejacking).

[edit] Pairing
Pairs of devices may establish a trusted relationship by learning (by user input) a shared secret known as a passkey. A device that wants to communicate only with a trusted device can cryptographically authenticate the identity of the other device. Trusted devices may also encrypt the data that they exchange over the air so that no one can listen in. The encryption can, however, be turned off, and passkeys are stored on the device file system, not on the Bluetooth chip itself. Since the Bluetooth address is permanent, a pairing is preserved, even if the Bluetooth name is changed. Pairs can be deleted at any time by either device. Devices generally require pairing or prompt the owner before they allow a remote device to use any or most of their services. Some devices, such as Sony Ericsson phones, usually accept OBEX business cards and notes without any pairing or prompts.
Certain printers and access points allow any device to use its services by default, much like unsecured Wi-Fi networks. Pairing algorithms are sometimes manufacturer-specific for transmitters and receivers used in applications such as music and entertainment.

[edit] Air interface
The protocol operates in the license-free ISM band at 2.4-2.4835 GHz. To avoid interfering with other protocols that use the 2.45 GHz band, the Bluetooth protocol divides the band into 79 channels (each 1 MHz wide) and changes channels up to 1600 times per second. Implementations with versions 1.1 and 1.2 reach speeds of 723.1 kbit/s. Version 2.0 implementations feature Bluetooth Enhanced Data Rate (EDR) and reach 2.1 Mbit/s. Technically, version 2.0 devices have a higher power consumption, but the three times faster rate reduces the transmission times, effectively reducing power consumption to half that of 1.x devices (assuming equal traffic load).
Bluetooth differs from Wi-Fi in that the latter provides higher throughput and covers greater distances, but requires more expensive hardware and higher power consumption. They use the same frequency range, but employ different multiplexing schemes. While Bluetooth is a cable replacement for a variety of applications, Wi-Fi is a cable replacement only for local area network access. Bluetooth is often thought of as wireless USB, whereas Wi-Fi is wireless Ethernet, both operating at much lower bandwidth than the cable systems they are trying to replace. However, this analogy is not entirely accurate since any Bluetooth device can, in theory, host any other Bluetooth device—something that is not universal to USB devices.
Many USB Bluetooth adapters are available, some of which also include an IrDA adapter. Older (pre-2003) Bluetooth adapters, however, have limited services, offering only the Bluetooth Enumerator and a less-powerful Bluetooth Radio incarnation. Such devices can link computers with Bluetooth, but they do not offer much in the way of services that modern adapters do.

[edit] Security
Bluetooth implements authentication and key derivation with custom algorithms based on the SAFER+ block cipher. The initialization key and master key are generated with the E22 algorithm.[16] The E0 stream cipher is used for encrypting packets. This makes eavesdropping on Bluetooth-enabled devices more difficult.

[edit] Social concerns

[edit] Security concerns
2003:In November 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered that serious flaws in Bluetooth security may lead to disclosure of personal data.[17] It should be noted, however, that the reported security problems concerned some poor implementations of Bluetooth, rather than the protocol itself.
In a subsequent experiment, Martin Herfurt from the trifinite.group was able to do a field-trial at the CeBIT fairgrounds, showing the importance of the problem to the world. A new attack called BlueBug was used for this experiment.[18]
2004:In April 2004, security consultant firm @stake (now Symantec) revealed a security flaw that makes it possible to crack conversations on Bluetooth based wireless headsets by reverse engineering the PIN.[citation needed]
This is one of a number of concerns that have been raised over the security of Bluetooth communications. In 2004 the first purported virus using Bluetooth to spread itself among mobile phones appeared on the Symbian OS.[19] The virus was first described by Kaspersky Lab and requires users to confirm the installation of unknown software before it can propagate.
The virus was written as a proof-of-concept by a group of virus writers known as 29A and sent to anti-virus groups. Thus, it should be regarded as a potential (but not real) security threat to Bluetooth or Symbian OS since the virus has never spread in the wild.
In August 2004, a world-record-setting experiment (see also Bluetooth sniping) showed that the range of Class 2 Bluetooth radios could be extended to 1.78 km (1.08 mile) with directional antennas.[20] This poses a potential security threat because it enables attackers to access vulnerable Bluetooth-devices from a distance beyond expectation. However, such experiments do not work without signal amplifiers. The attacker must also be able to receive information from the victim to set up a connection. No attack can be made against a Bluetooth device unless the attacker knows its Bluetooth address and which channels to transmit on.
2005:In April 2005, Cambridge University security researchers published results of their actual implementation of passive attacks against the PIN-based pairing between commercial Bluetooth devices, confirming the attacks to be practicably fast and the Bluetooth symmetric key establishment method to be vulnerable. To rectify this vulnerability, they carried out an implementation which showed that stronger, asymmetric key establishment is feasible for certain classes of devices, such as handphones.[21]
In June 2005, Yaniv Shaked and Avishai Wool published the paper "Cracking the Bluetooth PIN1," which shows both passive and active methods for obtaining the PIN for a Bluetooth link. The passive attack allows a suitably equipped attacker to eavesdrop on communications and spoof if they were present at the time of initial pairing. The active method makes use of a specially constructed message that must be inserted at a specific point in the protocol, to make the master and slave repeat the pairing process. After that, the first method can be used to crack the PIN. This attack's major weakness is that it requires the user of the devices under attack to re-enter the PIN during the attack when the device prompts them to. Also, this active attack probably requires custom hardware, since most commercially available Bluetooth devices are not capable of the timing necessary.[22]
In August 2005, police in Cambridgeshire, England, issued warnings about thieves using Bluetooth-enabled phones to track other devices left in cars. Police are advising users to ensure that any mobile networking connections are de-activated if laptops and other devices are left in this way.[23]
2006:In April 2006, researchers from Secure Network and F-Secure published a report that warns of the large number of devices left in a visible state, and issued statistics on the spread of various Bluetooth services and the ease of spread of an eventual Bluetooth worm.[24]
In October 2006, at the Luxemburgish Hack.lu Security Conference, Kevin Finistere and Thierry Zoller demonstrated and released a remote root shell over Bluetooth on Mac OSX 10.3.9 and 10.4. They also demonstrated the first Bluetooth PIN and Linkkeys cracker, which is based on the research of Wool and Shaked.
Bluejacking:Bluejacking allows phone users to send business cards anonymously using Bluetooth wireless technology. Bluejacking does NOT involve the removal or alteration of any data from the device. These business cards often have a clever or flirtatious message rather than the typical name and phone number. Bluejackers often look for the receiving phone to ping or the user to react. They then send another, more personal message to that device. Once again, in order to carry out a bluejacking, the sending and receiving devices must be within range of each other, which is typically 10 meters for most mobile devices. Phone owners who receive bluejack messages should refuse to add the contacts to their address book. Devices that are set in non-discoverable mode are not susceptible to bluejacking.

[edit] Health concerns
Bluetooth uses the microwave radio frequency spectrum in the 2.4 GHz to 2.4835 GHz range. Maximum power output from a Bluetooth radio is 1 mW, 2.5 mW, and 100 mW for Class 3, Class 2, and Class 1 devices respectively, which puts Class 1 at roughly the same level as cell phones, and the other two classes much lower.[25] Accordingly, Class 2 and Class 3 Bluetooth devices are considered less of a potential hazard than cell phones, and Class 1 may be comparable to that of cell phones.

[edit] Origin of the name and the logo
Bluetooth was named after a late tenth century king, Harald Bluetooth King of Denmark and Norway. He is known for his unification of previously warring tribes from Denmark (including now Swedish Scania, where the Bluetooth technology was invented), and Norway. Bluetooth likewise was intended to unify different technologies, such as computers and mobile phones.
The name may have been inspired less by the historical Harald than the loose interpretation of him in The Long Ships by Frans Gunnar Bengtsson, a Swedish Viking-inspired novel.
The Bluetooth logo merges the Nordic runes analogous to the modern Latin H and B: hagall and bjarkan from the Younger Futhark runes forming a bind rune.

[edit] Bluetooth Consortium
In 1998, Ericsson, IBM, Intel, and Nokia, formed a consortium and adopted the code name Bluetooth for their proposed open specification. In December 1999, 3Com, Lucent Technologies, Microsoft, and Motorola joined the initial founders as the promoter group. Since that time, Lucent Technologies transferred their membership to their spinoff Agere Systems, and 3Com has left the promoter group.

Virtual Digital Cable

2007-06-27T14:59:00.000+05:30

VDC Corporation, based in Northbrook, Illinois, is a multichannel video programming distributor, delivering live cable television through broadband connected computers in the United States. They develop and are involved in the distribution and delivery of live cable television programming channels.
Contents[hide]
1 History
2 Current Service
3 Controversies
4 VDC Legal Filings at The FCC
5 References
6 External links
//

[edit] History
VDC Corporation was founded in 2002 by Scott Wolf. VDC was a pioneer in the delivery of live cable programming to mobile devices. The company transitioned its mobile product to the delivery of live cable television to desktop computers with their Virtual Digital Cable service launched in April of 2006.
In January of 2007, VDC made public its decision to file a Program Access complaint with the FCC to commence a proceeding to obtain enforcement of the program access rules under the 1992 Cable TV Consumer Protection Act, to ensure vertically integrated programming providers sell their programming to VDC. Such providers include Time Warner (CNN, TNT, TBS, Cartoon Network, HBO), Liberty Media, (Discovery Channel), Cablevision (Rainbow) and Comcast (E!, Golf Channel).

[edit] Current Service
Currently VDC offers a single subscription package for $8.95 per month, which gives users access to all channels in VDC's current lineup.

[edit] Controversies
Congress attempted to encourage growth and competition in the vertically integrated cable marketplace with the 1992 Cable TV Consumer Protection Act. Using the internet, VDC has brought diversity and increased competition to the marketpalce:
"The term ‘multichannel video programming distributor’ means an entity engaged in the business of making available for purchase, by subscribers or customers, multiple channels of video programming. Such entities include, but are not limited to, a cable operator, a multichannel multipoint distribution service, a direct broadcast satellite service, a television receive-only satellite program distributor, and a satellite master antenna television system operator, as well as buying groups or agents of all such entities." [1]
VDC's complaint with the FCC was filed against Turner Broadcasting System [2] to force Turner into compliance with the 1992 Cable Act and to recognize VDC as an MVPD. This would grant VDC mandatory access to broadcast Turner's programming on VDC's MVPD system.
The FCC debate also raises regulatory and broadcast issues involving net neutrality.

[edit] VDC Legal Filings at The FCC
VDC's Reply to Turner's 'Motion to Dismiss'
Turner: 'Motion to Dismiss and Answer' Evasion of 1992 Cable Act and Program Access Rules
Deceptive Acts and Unfair Methods of Competition
Complaint Filed against WBBM-TV Chicago

WAP WIRELESS COMMUNICATION

2007-06-22T17:22:00.000+05:30

WAP, Wireless Application Protocol aims to provide Internet content and advanced telephony services to digital mobile phones, pagers and other wireless terminals. The protocol family works across different wireless network environments and makes web pages visible on low-resolution and low-bandwidth devices. WAP phones are "smart phones" allowing their users to respond to e-mail, access computer databases and to empower the phone to interact with Internet-based content and e-mail.
WAP specifies a Wireless application Environment and Wireless Protocols. The Wireless application environment (WAE) is based on WSP (Wireless Session Protocol) and WTP (Wireless Transaction Protocol).
The OSI Model for Wireless Communication
WAP Protocol stack
The basic construction of WAP architecture can be explained using the following model. The order of the independent levels – which are a hierarchy - has the advantage that the system is very flexible and can be scaled up or down. Because of the different levels – or stacks - this is called the "WAP Stack", which is divided into 5 different levels.
Application Layer: Wireless Application Environment (WAE).
Session Layer: Wireless Session Protocol (WSP).
Transaction Layer: Wireless Transaction Protocol (WTP).
Security Layer: Wireless Transport Layer Security (WTLS).
Transport Layer: Wireless Datagram Protocol (WDP).
Each stack overlaps with the stack below. This stack architecture makes it possible for software manufacturers to develop applications and services for certain stacks. They may even develop services for stacks which are not specified yet.
The WAP stack is an entity of protocols which cover the wireless data transfer. The diagram above shows the order of the different stacks and their protocols. This includes the stacks responsible for the layout as well as the stacks resposible for the actual data transfer. The highest level or stack is the one which deals with the layout. A lower stack is responsible for the transfer and the security through WTLS (Wireless Transport Layer Security). All stacks lower than this one are being called network stack. Due to this hierarchy of stacks any changes made in the network stacks will have no influence over the stacks above
Application Layer (WAE and WTA)
The environment for wireless applications (Wireless Application Environment WAE) and the application for wireless phones (Wireless Telephony Application WTA) are the highest layer in the hierarchy of WAP architechture. These two are the main interface to the client device, which gives and controls the description language, the script language of any application and the specifics of the telephony. WAE and WTA have only a few easy functions on the client device, like the maintenance of a history list, for example.
Session Layer (Wireless Session Protocol WSP)
The Wireless Session Protocol (WSP) has all the specifications for a session. It is the interface between the application layer and the transfer layer and delivers all functions that are needed for wireless connections. A session mainly consists of 3 phases: start of the session, transfering information back and forth and the end of the session. Additionally, a session can be interrupted and started again (from the point where it was interrupted.)
Transaction Layer (Wireless Transaction Protocol WTP)
The specifications for the transfer layer are in the Wireless Transaction Protocol (WTP). Like the User Datagramm Protocol (UDP), the WTP runs at the head of the datagramm service. Both the UDP and the WTP are a part of the standard application from the TCP/IP to make the simplified protocol compatible to mobile terminals. WTP supports chaining together protocol data and the delayed response to reduce the number of transmissions. The protocol tries to optimize user interaction in order that information can be received when needed.Wireless Transport Layer Security WTLS
The Wireless Transport Layer Security (WTLS) is a optional layer or stack which consists of description devices. A secure transmission is crucial for certain applications such as e-commerce or WAP-banking and is a standard in these days. Furthermore WTLS contains a check for data integrity, user authentification and gateway security.
Transport Layer (Wireless Datagram Protocol WDP)
The Wireless Datagram Protocol (WDP) represents the transfer or transmission layer and is also the interface of the network layer to all the above stacks/layers. With the help of WDP the transmission layer can be assimilated to the specifications of a network operator. This means that WAP is completely independent from any network operator. The transmission of SMS, USSD, CSD, CDPD, IS-136 packet data and GPRS is supported. The Wireless Control Message Protocol (WCMP) is an optional addition to WAP, which will inform users about occurred errors.

WTLS
Wapforum version 11/99
Wireless Transport Layer Security is a protocol based on the TLS protocol. It is used with the WAP transport protocols and has been optimised for use over narrow-band communication channels. The WTLs layer is above the transport protocol layer. The required security layer of the protocol determines whether it is used or not. It provides a secure transport service interface that preserves the transport service interface below; additionally it provides an interface for managing secure connections. WTLS aims to provide privacy, data integrity and authentication between two communication applications. Among its features are datagram support, optimised handshaking and dynamic key refreshing. It is optimised for low-bandwidth bearer networks with relatively long latency.
The WTLS Record Protocol is a layered protocol. The Record Protocol takes messages to be transmitted, optionally compresses the data, applies a MAC, encrypts, and transmits the result. Received data is decrypted, verified, and decompressed, then delivered to higher-level clients. Four record protocol clients are described in the WTLS standard; the change cipher spec protocol, the handshake protocol, the alert protocol and the application data protocol. If a WTLS implementation receives a record type it does not understand, it ignores it. Several records can be concatenated into one transport SDU. For example, several handshake messages can be transmitted in one transport SDU. This is particularly useful with packet-oriented transports such as GSM short messages.
Handshakeprotocols
Alert Protocol
ApplicationProtocol
Change CipherSpec Protocol
Record protocol
The handshake protocol is made up of 3 sub-protocols. All messages are encapsulated in a plaintext structure.
Interested in more details about testing this protocol?

WTP
WAPforum WTP 11/6/99
The Wireless Transaction Protocol provides the services necessary for interactive browsing applications. During a browsing session the client requests information from a server and the server responds with the information. This is referred to as a transaction. WTP runs on a datagram service and possible a security service.
Advantages of WTP include:
Improved reliability over datagram services
Imported efficiency over connection oriented services
As a message oriented protocol, it is designed for services oriented towards transactions.
Main features:
3 kinds of transaction services.
Class 0 Unreliable invoke messages with no result messages
Class 1: Reliable invoke messages with no result messages
Class 2: Reliable invoke messages with exactly one reliable result message.
Reliability achieved by using unique transaction identifiers, acknowledgements, duplicate removal; and retransmissions.
No explicit set up or tear down phases.
Optional user-to-user reliability.
Optionally the last acknowledgement of the transaction may contain out-of-band information.
Concatenation may be used to convey multiple PDUs in one service data unit of the datagram transport.
The basic unit of interchange is an entire message, not a stream of bytes.
Mechanisms are provided to minimize the number of transactions replayed as a result of duplicate packets.
Abort of outstanding transactions.
For reliable invoke messages, both success and failure reported.
Asynchronous transactions allowed.
The protocol data unit (PDU) consists of the header and data (if present). The header contains a fixed part and a variable part; The variable parts are carried in the Transport Information Item (TPI). Each PDU has its own fixed header (the fixed headers vary slightly in structure). As an example, the structure of the invoke PDU fixed header appears below:
1
2-5
6
7
8
Con
PDU Type
GTR
TTR
RID
TID
Version
TIDnew
U/P
RES
RES
TCL
CON continue flag (1 bit):The continue flag indicates the presence of any TPIs in the variable part. If the flag is set, there are one or more TPIs in the variable portion of the header. If the flag is clear, the variable part of the header is empty. This flag is also used as the first bit of a TPI, and indicates whether the TPI is the last of the variable header. If the flag is set, another TPI follows this TPI. If the flag is clear, the octet after this TPI is the first octet of the user data.
PDU typeThe PDU type determines the length and structure of the header and dictates what type of WTP PDU the PDU is (Invoke, Ack, etc). This provides information to the receiving WTP provider as to how the PDU data should be interpreted and what action is required.
The following PDU types are defined:
PDU Code
PDU Type
0x01
Invoke
0x02
Result
0x03
Ack
0x04
Abort
0x05
Segmented Invoke
0x06
Segmented Result
0x07
Negative Ack
Group trailer (GTR) and Transmission trailer (TTR) flag (2 bit):When segmentation and re-assembly is implemented, the TTR flag is used to indicate the last packet of the segmented message. The GTR flag is used to indicate the last packet of a packet group.
GTR/TTR flag combinations:
GTR TTR Description
00
Not last packet
01
Last packet of message
10
Last packet of packet group
11
Segmentation and Re-assembly NOT supported.
The default setting should be GTR=1 and TTR=1, that is, WTP segmentation and re-assembly not supported.
RID Re-transmission Indicator (1 bit):Enables the receiver to differentiate between packets duplicated by the network and packets re-transmitted by the sender. In the original message the RID is clear. When the message gets re-transmitted the RID is set.
TID Transaction identifier (16 bit):The TID is used to associate a packet with a particular transaction.
VersionThe current version is 0X00
TIDnew flagThis bit is set when the Initiator has wrapped the TID value, i.e. set it to be lower than the previous TID value.
U/PWhen this flag is set it indicates that the Initiator requires a User acknowledgement from the server WTP user. The WTP user confirms every received message.
RESThis is a reserved bit and its value should be set to 0.
TCLThe transaction class shows the desired transaction class in the invoke message.
Packet sequence number (8 bit):This is used by the PDUs belonging to the segmentation and re
Interested in more details about testing this protocol?

WSP
WAP WSP 5/11/99
The Session layer protocol family in the WAP architecture is called the Wireless Session Protocol, WSP. WSP provides the upper-level application layer of WAP with a consistent interface for two session services. The first is a connection-mode service that operates above a transaction layer protocol WTP, and the second is a connectionless service that operates above a secure or non-secure datagram transport service.
The Wireless Session Protocols currently offer services most suited for browsing applications. WSP provides HTTP 1.1 functionality (it is a binary form of HTTP) and incorporates new features such as long-lived sessions, a common facility for data push, capability negotiation and session suspend/resume. The protocols in the WSP family are optimized for low-bandwidth bearer networks with relatively long latency. Requests and responses can include both headers and data. WSP provides push and pull data transfer WSP functions on the transaction and datagram services.
Messages can be in connection mode or connectionless. Connection mode messages are carried over WTP. In this case the protocol consists of WTP protocol messages with WSP PDUs as their data. Connectionless messages consist only of the WSP PDUs.
The general structure of the WSP PDU is as follows:
1 bite1 bite

TID/PIDPDU Type
Type Specific Contents
TID/PIDTransaction ID or Push ID. The TID field is used to associate requests with replies in the connectionless session service. The presence of the TID is conditional. It is included in the connectionless WSP PDUs, and is not included in the connection-mode PDUs. In connectionless WSP, the TID is passed to and from the session user as the "Transaction Id" or "Push Id" parameters of the session primitive
PDU typeThe Type field specifies the type and function of the PDU. The type numbers for the various PDUs are defined below. The rest of the PDU is type-specific information, referred to as the contents.
Number
Name Assigned
0x00
Reserved
0x01
Connect
0x02
ConnectReply
0x03
Redirect
0x04
Reply
0x05
Disconnect
0x06
Push
0x07
ConfirmedPush
0x08
Suspend
0x09
Resume
0x10–0x3
FUnassigned
0x40
Get
0x41
Options (Get PDU)
0x42
Head (Get PDU)
0x43
Delete (Get PDU)
0x44
Trace (Get PDU)
0x45-0x4
FUnassigned (Get PDU)
0x50-0x5
FExtended Method (Get PDU)
0x60
Post
0x61
Put (Post PDU)
0x62–0x6
FUnassigned (Post PDU)
0x70-0x7
FExtended Method (Post PDU)
0x80-0x
FFReserved

2007-06-22T17:15:00.000+05:30

Ultra Slim Design, Fast Transfer Speed for Portable Storage Solution
The new Creative Portable Hard Disk lets you enjoy speedy transfer and carry huge data, digital music, digital video and presentation slides right in your pocket! Slim and lightweight, it provides a massive storage space that's more than enough to deal with everyday demands of a working executive or an ordinary home user. Complying with USB2.0 connectivity, Creative Portable Hard Disk is a plug and play ready device.
The Creative Portable Hard Disk is available in 20, 40 and 60GB capacities.

ON line HIndi Fm

2007-06-14T11:48:00.000+05:30

Hi,

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Optical fiber

2007-06-05T14:52:00.000+05:30

An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. In fibers with large core diameter, the confinement is based on total internal reflection. In smaller diameter core fibers, (widely used for most communication links longer than 200 meters) the confinement relies on establishing a waveguide. Fiber optics is the overlap of applied science and engineering concerned with such optical fibers. Optical fibers are widely used in fiber-optic communication, which permits transmission over longer distances and at higher data rates than other forms of wired and wireless communications. They are also used to form sensors, and in a variety of other applications.
The term optical fiber covers a range of different designs including graded-index optical fibers, step-index optical fibers, birefringent polarization-maintaining fibers and more recently photonic crystal fibers, with the design and the wavelength of the light propagating in the fiber dictating whether or not it will be multi-mode optical fiber or single-mode optical fiber. Because of the mechanical properties of the more common glass optical fibers, special methods of splicing fibers and of connecting them to other equipment are needed. Manufacture of optical fibers is based on partially melting a chemically doped preform and pulling the flowing material on a draw tower. Fibers are built into different kinds of cables depending on how they will be used.
Contents[hide]
1 History
2 Applications
2.1 Optical fiber communication
2.2 Fiber optic sensors
2.3 Other uses of optical fibers
3 Principle of operation
3.1 Multimode fiber
3.2 Singlemode fiber
3.3 Special-purpose fiber
3.4 Materials
3.5 Fiber fuse
4 Manufacturing
5 Optical fiber cables
6 Termination and splicing
7 See also
8 Notes
9 References
10 External links
//

[edit] History
The light-guiding principle behind optical fibers was first demonstrated in by Daniel Collodon and Jaques Babinet in the 1840s, with Irish inventor John Tyndall offering public displays using water-fountains ten years later.[1] Practical applications, such as close internal illumination during dentistry, appearing early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for internal medical examinations by Heinrich Lamm in the following decade. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared in the 1950s.[1] Optical fibers became practical for use in communications in the late 1970s, once the attenuation was reduced sufficiently; since then, several technical advances have been made to improve the attenuation and dispersion properties of optical fibers (i.e., allowing signals to travel farther and carry more information), and lower the cost of fiber communications systems. In 1952 physicist Narinder Singh Kapany conducted experiments that led to the invention of optical fiber, based on Tyndall's earlier studies. Later development, in the early-to-mid twentieth century, focused on the development of fiber bundles for image transmission, with the primary application being the medical gastroscope. The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material. A variety of other image transmission applications soon followed.

[edit] Applications

[edit] Optical fiber communication
Main article: Fiber-optic communication
Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters. Additionally, the light signals propagating in the fiber can be modulated at rates as high as 40 Gb/s, and each fiber can carry many independent channels, each carried by a different wavelength of light. In total, a single fiber-optic cable can carry data at rates as high as 14444 Tb/s. Over short distances, such as networking within a building, fiber saves space in cable ducts because a single fiber can carry much more data than a single electrical cable. Fiber is also immune to electrical interference, which prevents cross-talk between signals in different cables and pickup of environmental noise. Because they are non-electrical, fiber cables can be used in environments where explosive fumes are present, without danger of ignition.
Although fibers can be made out of transparent plastic, glass, or a combination of the two, the fibers used in long-distance telecommunications applications are always glass, because of the lower optical attenuation. Both multi-mode and single-mode fibers are used in communications, with multi-mode fiber used mostly for short distances (up to 500 m), and single-mode fiber used for longer distance links. Because of the tighter tolerances required to couple light into and between single-mode fibers; single-mode transmitters, receivers, amplifiers and other components are generally more expensive than multi-mode components.

[edit] Fiber optic sensors
Optical fibers can be used as sensors to measure strain, temperature, pressure and other parameters. The small size and the fact that no electrical power is needed at the remote location gives the fiber optic sensor advantages to conventional electrical sensor in certain applications.
Optical fibers are used as hydrophones for seismic or SONAR applications. Hydrophone systems with more than 100 sensors per fiber cable have been developed. Hydrophone sensor systems are used by the oil industry as well as a few countries' navies. Both bottom mounted hydrophone arrays and towed streamer systems are in use. The German company Sennheiser developed a microphone working with a laser and optical fibers[2].
Optical fiber sensors for temperature and pressure have been developed for downhole measurement in oil wells. The fiber optic sensor is well suited for this environment as it is functioning at temperatures too high for semiconductor sensors (Distributed Temperature Sensing).
Another use of the optical fiber as a sensor is the optical gyroscope which is in use in the Boeing 767 and in some car models (for navigation purposes) and the use in Hydrogen microsensors.

[edit] Other uses of optical fibers

A frisbee illuminated by fiber optics
Fibers are widely used in illumination applications. They are used as light guides in medical and other applications where bright light needs to be shone on a target without a clear line-of-sight path. In some buildings, optical fibers are used to route sunlight from the roof to other parts of the building (see non-imaging optics). Optical fiber illumination is also used for decorative applications, including signs, art, and artificial Christmas trees. Swarovski boutiques use optical fibers to illuminate their crystal showcases from many different angles while only employing one light source. Optical fiber is an intrinsic part of the light-transmitting concrete building product, LiTraCon.

A fiber-optic Christmas Tree
Optical fiber is also used in imaging optics. A coherent bundle of fibers is used, sometimes along with lenses, for a long, thin imaging device called an endoscope, which is used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures (endoscopy). Industrial endoscopes (see fiberscope or borescope) are used for inspecting anything hard to reach, such as jet engine interiors.
An optical fiber doped with certain rare-earth elements such as erbium can be used as the gain medium of a laser or optical amplifier. Rare-earth doped optical fibers can be used to provide signal amplification by splicing a short section of doped fiber into a regular (undoped) optical fiber line. The doped fiber is optically pumped with a second laser wavelength that is coupled into the line in addition to the signal wave. Both wavelengths of light are transmitted through the doped fiber, which transfers energy from the second pump wavelength to the signal wave. The process that causes the amplification is stimulated emission.
Optical fibers doped with a wavelength shifter are used to collect scintillation light in physics experiments.
Optical fiber can be used to supply a low level of power (around one watt) to electronics situated in a difficult electrical environment. Examples of this are electronics in high-powered antenna elements and measurement devices used in high voltage transmission equipment.

[edit] Principle of operation
An optical fiber is a cylindrical dielectric waveguide that transmits light along its axis, by the process of total internal reflection. The fiber consists of a core surrounded by a cladding layer. To confine the optical signal in the core, the refractive index of the core must be greater than that of the cladding. The boundary between the core and cladding may either be abrupt, in step-index fiber, or gradual, in graded-index fiber.

[edit] Multimode fiber

The propagation of light through a multi-mode optical fiber.
Fiber with large (greater than 10 μm) core diameter may be analyzed by geometric optics. Such fiber is called multimode fiber, from the electromagnetic analysis (see below). In a step-index multimode fiber, rays of light are guided along the fiber core by total internal reflection. Rays that meet the core-cladding boundary at a high angle (measured relative to a line normal to the boundary), greater than the critical angle for this boundary, are completely reflected. The critical angle (minimum angle for total internal reflection) is determined by the difference in index of refraction between the core and cladding materials. Rays that meet the boundary at a low angle are refracted from the core into the cladding, and do not convey light and hence information along the fiber. The critical angle determines the acceptance angle of the fiber, often reported as a numerical aperture. A high numerical aperture allows light to propagate down the fiber in rays both close to the axis and at various angles, allowing efficient coupling of light into the fiber. However, this high numerical aperture increases the amount of dispersion as rays at different angles have different path lengths and therefore take different times to traverse the fiber. A low numerical aperture may therefore be desirable.
In graded-index fiber, the index of refraction in the core decreases continuously between the axis and the cladding. This causes light rays to bend smoothly as they approach the cladding, rather than reflecting abruptly from the core-cladding boundary. The resulting curved paths reduce multi-path dispersion because high angle rays pass more through the lower-index periphery of the core, rather than the high-index center. The index profile is chosen to minimize the difference in axial propagation speeds of the various rays in the fiber. This ideal index profile is very close to a parabolic relationship between the index and the distance from the axis.

[edit] Singlemode fiber

A typical single-mode optical fiber, showing diameters of the component layers.
Fiber with a core diameter less than about ten times the wavelength of the propagating light cannot be modeled using geometric optics. Instead, it must be analyzed as an electromagnetic structure, by solution of Maxwell's equations as reduced to the electromagnetic wave equation. The electromagnetic analysis may also be required to understand behaviors such as speckle that occur when coherent light propagates in multi-mode fiber. As an optical waveguide, the fiber supports one or more confined transverse modes by which light can propagate along the fiber. Fiber supporting only one mode is called single-mode or mono-mode fiber. The behavior of larger-core multimode fiber can also be modeled using the wave equation, which shows that such fiber supports more than one mode of propagation (hence the name). The results of such modeling of multi-mode fiber approximately agree with the predictions of geometric optics, if the fiber core is large enough to support more than a few modes.
The waveguide analysis shows that the light energy in the fiber is not completely confined in the core. Instead, especially in single-mode fibers, a significant fraction of the energy in the bound mode travels in the cladding as an evanescent wave.
The most common type of single-mode fiber has a core diameter of 8 to 10 μm and is designed for use in the near infrared. It is notable that the mode structure depends on the wavelength of the light used, so that this fiber actually supports a small number of additional modes at visible wavelengths. Multi-mode fiber, by comparison, is manufactured with core diameters as small as 50 microns and as large as hundreds of microns.

[edit] Special-purpose fiber
Some special-purpose optical fiber is constructed with a non-cylindrical core and/or cladding layer, usually with an elliptical or rectangular cross-section. These include polarization-maintaining fiber and fiber designed to suppress whispering gallery mode propagation.

[edit] Materials
Glass optical fibers are almost always made from silica, but some other materials, such as fluorozirconate, fluoroaluminate, and chalcogenide glasses, are used for longer-wavelength infrared applications. Like other glasses, these glasses have a refractive index of about 1.5. Typically the difference between core and cladding is less than one percent.
Plastic optical fiber (POF) is commonly step-index multimode fiber, with core diameter of 1 mm or larger. POF typically has much higher attenuation than glass fiber (that is, the amplitude of the signal in it decreases faster), 1 dB/m or higher, and this high attenuation limits the range of POF-based systems.

[edit] Fiber fuse
At high optical intensities, above 2 megawatts per square centimetre, when a fiber is subjected to a shock or is otherwise suddenly damaged, a fiber fuse can occur. The reflection from the damage vaporizes the fiber immediately before the break, and this new defect remains reflective so that the damage propagates back toward the transmitter at 1–3 meters per second [3],[4],[5]. The open fiber control system, which ensures laser eye safety in the event of a broken fiber, can also effectively halt propagation of the fiber fuse [6]. In situations, such as undersea cables, where high power levels might be used without the need for open fiber control, a "fiber fuse" protection device at the transmitter can break the circuit to prevent any damage.

[edit] Manufacturing
Standard optical fibers are made by first constructing a large-diameter preform, with a carefully controlled refractive index profile, and then pulling the preform to form the long, thin optical fiber. The preform is commonly made by three chemical vapor deposition methods: inside vapor deposition, outside vapor deposition, and vapor axial deposition.
With inside vapor deposition, a hollow glass tube approximately 40 cm in length known as a "preform" is placed horizontally and rotated slowly on a lathe, and gases such as silicon tetrachloride (SiCl4) or germanium tetrachloride (GeCl4) are injected with oxygen in the end of the tube. The gases are then heated by means of an external hydrogen burner, bringing the temperature of the gas up to 1900 Kelvin, where the tetrachlorides react with oxygen to produce silica or germania (germanium oxide) particles. When the reaction conditions are chosen to allow this reaction to occur in the gas phase throughout the tube volume, in contrast to earlier techniques where the reaction occurred only on the glass surface, this technique is called modified chemical vapor deposition.
The oxide particles then agglomerate to form large particle chains, which subsequently deposit on the walls of the tube as soot. The deposition is due to the large difference in temperature between the gas core and the wall causing the gas to push the particles outwards (this is known as thermophoresis). The torch is then traversed up and down the length of the tube to deposit the material evenly. After the torch has reached the end of the tube, it is then brought back to the beginning of the tube and the deposited particles are then melted to form a solid layer. This process is repeated until a sufficient amount of material has been deposited. For each layer the composition can be varied by varying the gas composition, resulting in precise control of the finished fiber's optical properties.
In outside vapor deposition or vapor axial deposition, the glass is formed by flame hydrolysis, a reaction in which silicon tetrachloride and germanium tetrachloride are oxidized by reaction with water (H2O) in an oxyhydrogen flame. In outside vapor deposition the glass is deposited onto a solid rod, which is removed before further processing. In vapor axial deposition, a short seed rod is used, and a porous preform, whose length is not limited by the size of the source rod, is built up on its end. The porous preform is consolidated into a transparent, solid preform by heating to about 1800 Kelvin.
The preform, however constructed, is then placed in a device known as a drawing tower, where the preform tip is heated and the optic fiber is pulled out as a string. By measuring the resultant fiber width, the tension on the fiber can be controlled to maintain the fiber thickness.
This manufacturing process is accomplished by numerous optical fiber companies like Corning, OFS, Sterlite Optical Technologies, Furukawa, Sumitomo, Fujikura and Prysmian. In addition, various fiber optic component manufacturers, assembly houses, and custom fiber optic providers exist.

[edit] Optical fiber cables
In practical fibers, the cladding is usually coated with a tough resin buffer layer, which may be further surrounded by a jacket layer, usually plastic. These layers add strength to the fiber but do not contribute to its optical wave guide properties. Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications.[7]
For indoor applications, the jacketed fiber is generally enclosed, with a bundle of flexible fibrous polymer strength members like Aramid (e.g. Twaron or Kevlar), in a lightweight plastic cover to form a simple cable. Each end of the cable may be terminated with a specialized optical fiber connector to allow it to be easily connected and disconnected from transmitting and receiving equipment.
For use in more strenuous environments, a much more robust cable construction is required. In loose-tube construction the fiber is laid helically into semi-rigid tubes, allowing the cable to stretch without stretching the fiber itself. This protects the fiber from tension during laying and due to temperature changes. Alternatively the fiber may be embedded in a heavy polymer jacket, commonly called "tight buffer" construction. These fiber units are commonly bundled with additional steel strength members, again with a helical twist to allow for stretching.
Another critical concern in cabling is to protect the fiber from contamination by water, because its component hydrogen (hydronium) and hydroxyl ions can diffuse into the fiber, reducing the fiber's strength and increasing the optical attenuation. Water is kept out of the cable by use of solid barriers such as copper tubes, water-repellant jelly, or more recently water absorbing powder, surrounding the fiber.
Finally, the cable may be armored to protect it from environmental hazards, such as construction work or gnawing animals. Undersea cables are more heavily armored in their near-shore portions to protect them from boat anchors, fishing gear, and even sharks, which may be attracted to the electrical power signals that are carried to power amplifiers or repeaters in the cable.
Modern fiber cables can contain up to a thousand fibers in a single cable, so the performance of optical networks easily accommodates even today's demands for bandwidth on a point-to-point basis. However, unused point-to-point potential bandwidth does not translate to operating profits, and it is estimated that no more than 1% of the optical fiber buried in recent years is actually 'lit'.
Modern cables come in a wide variety of sheathings and armor, designed for applications such as direct burial in trenches, dual use as power lines [1], installation in conduit, lashing to aerial telephone poles, submarine installation, or insertion in paved streets. In recent years the cost of small fiber-count pole mounted cables has greatly decreased due to the high Japanese and South Korean demand for Fiber to the Home (FTTH) installations.

[edit] Termination and splicing

ST fiber connector on multimode fiber
Optical fibers are connected to terminal equipment by optical fiber connectors. These connectors are usually of a standard type such as FC, SC, ST, LC, or MTRJ.
Optical fibers may be connected to each other by connectors or by splicing, that is, joining two fibers together to form a continuous optical waveguide. The generally accepted splicing method is arc fusion splicing, which melts the fiber ends together with an electric arc. For quicker fastening jobs, a "mechanical splice" is used.
Fusion splicing is done with a specialized instrument that typically operates as follows: The two cable ends are fastened inside a splice enclosure that will protect the splices, and the fiber ends are stripped of their protective polymer coating (as well as the more sturdy outer jacket, if present). The ends are cleaved (cut) with a precision cleaver to make them perpendicular, and are placed into special holders in the splicer. The splice is usually inspected via a magnified viewing screen to check the cleaves before and after the splice. The splicer uses small motors to align the end faces together, and emits a small spark between electrodes at the gap to burn off dust and moisture. Then the splicer generates a larger spark that raises the temperature above the melting point of the glass, fusing the ends together permanently. The location and energy of the spark is carefully controlled so that the molten core and cladding don't mix, and this minimizes optical loss. A splice loss estimate is measured by the splicer, by directing light through the cladding on one side and measuring the light leaking from the cladding on the other side. A splice loss under 0.1 dB is typical. The complexity of this process is the major thing that makes fiber splicing more difficult than splicing copper wire.
Mechanical fiber splices are designed to be quicker and easier to install, but there is still the need for stripping, careful cleaning and precision cleaving. The fiber ends are aligned and held together by a precision-made sleeve, often using a clear gel (index matching gel) that enhances the transmission of light across the joint. Such joints typically have higher optical loss, and are less robust than fusion splices, especially if the gel is used. All splicing techniques involve the use of an enclosure into which the splice is placed for protection afterward.
Fibers are terminated in connectors so that the fiber end is held at the end face precisely and securely. A fiber optic connector is basically a rigid cylindrical barrel surrounded by a sleeve that holds the barrel in its mating socket. It can be push and click, turn and latch, or threaded. A typical connector is installed by preparing the fiber end and inserting it into the rear of the connector body. Quick set glue is usually used so the fiber is held securely, and a strain relief is secured to the rear. Once the glue has set, the end is polished to a mirror finish. Various types of polish profile are used, depending on the type of fiber and the application. For singlemode fiber, the fiber ends are typically polished with a slight curvature, such that when the connectors are mated the fibers touch only at their cores. This is known as a "physical contact" (PC) polish. The curved surface may be polished at an angle, to make an angled physical contact (APC) connection. Such connections have higher loss than PC connections, but greatly reduced backreflection, because light that reflects from the angled surface leaks out of the fiber core; the resulting loss in signal strength is known as gap loss.
Various methods to align two fiber ends to each other or one fiber to an optical device (VCSEL, LED, waveguide etc.) have been reported. They all follow either an active fiber alignment approach or a passive fiber alignment approach.
In 1965, Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables were the first to suggest that attenuation of contemporary fibers was caused by impurities, which could be removed, rather than fundamental physical effects such as scattering. They speculated that optical fiber could be a practical medium for communication, if the attenuation could be reduced below 20 dB per kilometer (Hecht, 1999, p. 114).This attenuation level was first achieved in 1970, by researchers Robert D. Maurer, Donald Keck, Peter Schultz, and Frank Zimar working for American glass maker Corning Glass Works, now Corning Inc. They demonstrated a fiber with 17 dB optic attenuation per kilometer by doping silica glass with titanium. A few years later they produced a fiber with only 4 db/km using germanium oxide as the core dopant. Such low attenuations ushered in optical fiber telecommunications and enabled the Internet.
On 22 April, 1977, General Telephone and Electronics sent the first live telephone traffic through fiber optics, at 6 Mbit/s, in Long Beach, California.
The erbium-doped fiber amplifier, which reduced the cost of long-distance fiber systems by eliminating the need for optical-electrical-optical repeaters, was invented by David Payne of the University of Southampton, and Emmanuel Desurvire at Bell Laboratories in 1986. The two pioneers were awarded the Benjamin Franklin Medal in Engineering in 1998.
The first transatlantic telephone cable to use optical fiber was TAT-8, based on Desurvire optimized laser amplification technology. It went into operation in 1988.
TAT-8 was developed as the first transatlantic undersea fiber optic link between the United States and Europe. TAT-8 is more than 3000 nautical miles in length and was the first oceanic fiber optic cable. It was designed to handle a mix of information. When inaugurated, it had an estimated lifetime in excess of 20 years. TAT-8 was the first of a new class of cables, even though it had already been used in long-distance land and short-distance undersea operations. Its installation was preceded by extensive deep-water experiments and trials conducted in the early 1980s to demonstrate the project's feasibility.
In 1991, the emerging field of photonic crystals led to the development of photonic crystal fiber (Science (2003), vol 299, page 358), which guides light by means of diffraction from a periodic structure, rather than total internal reflection. The first photonic crystal fibers became commercially available in 1996 [2]. Photonic crystal fibers can be designed to carry higher power than conventional fiber, and their wavelength dependent properties can be manipulated to improve their performance in certain applications.

The Scope of Biotechnology: the Indian Advantage

2007-05-24T16:40:00.000+05:30

Biotechnology may be as old as human civilization but modern biotechnology is less than three decades old. Traditional Biotechnology that led to the development of processes for producing products like yogurt, Vinegar, alcohol and cheese was entirely empirical and bereft of any understanding of the mechanisms that led to the product. There was no possibility of a deliberate design to produce a desired new product.In modern biotechnology, we use the in- depth understanding we have gained in the last five decades. The mechanisms that underlie the variety of functions performed by living organisms, to produce a desired new or old product. In the case of an established product, the new biotechnological process is cheaper and better in many respects than the earlier processes.Modern biotechnology has been, infact, an historical imperative. Its emergence on the world scene was predicted at least four decades ago. The term, genetic engineering, was coined independently in 1973 by the author of an article in The Guardian in the UK, and in a syndicated article by the present author in India.
Pushpa M. Bhargava, one of India’s most brilliant scientists, has founded and directed the Centre for Cellular and Molecular Biology (CCMB), Hyderabad.His scientific contributions include the preparation and characterization of primary lever cell suspensions, identification of proteins from the seminal plasma and extensive characterization of one of these proteins and seminal plasmin. He has been awarded with Padma Bhushan, the Legion d’ Honneur, the Wattumul Memorial Prize and Goyal Prize.
Today’s biotechnology consists of at least twenty-five areas each area being characterized by the use of a different set of technologies.Scope of BiotechnologyGenetic engineering: Genetic Engineering of microbes, plants and animals (including marine animals). Genetic engineering implies conferring new capabilities on an organism by Transferring into an organism the appropriate DNA (De oxyribo Nucleic Acid, the genetic material) of another having these capabilities does this. Then ensures that these capabilities are converted into abilities. Thus the common yeast, Sacchromyces cerevisciae cannot make the protein, human insulin, but we can make it to do so by introducing in it the gene for human insulin (that is, the appropriate DNA fragment coding for this protein). After integrating the insulin gene in yeast DNA, creates condition for the insulin to express itself to produce insulin through the normal process of transfer of information from DNA to protein.Genetically engineered microbes are today widely used for producing drugs and vaccines in large scale at low costs that are of great importance (human insulin, erythropoietin, and hepatitis-B vaccine). For example genetically engineered plants that make their own pesticides or are resistant to weedicides- are already in the market. Thus, over 60 percent of the acreage under soyabean in the United States have now genetically engineered soyabean that is resistant to the weedicides, Roundup. The total acreage under genetically engineered crops (for good or for bad) around the world exceeds 100 million acres today.Genetically engineering plants are also poised to produce vaccines. A few hundred acres of genetically engineered banana plantation can provide enough vaccine to immunize 120 million children every year that need to be protected against four common diseases. One of the future sources of cheap protein-drugs in the coming years, would be genetically engineered animals who would secrete these drugs in abundance (1-15 mg/ml) in their milk. They will be available at a cost of three or more times lower than the current cost.Gene Therapy: This is in a way, genetic engineering of humans, which would allow a person suffering from a disabling genetic disorder to lead a normal life.Immunotechnologies: Such as monoclonal antibodies (MABs) for diagnosis and therapy. Antibodies, special sets of proteins present in humans that enable them to fight incursion of their bodies by harmful chemicals or micro organisms. Monoclonal antibodies are single chemical species of antibodies produced in the laboratory by a special technique. Nobel Prize was awarded for this in the 1980’s to Cesar Milstein and Georges Kashler. Mouse MAB’s can be used for the diagnosis of human diseases. As human MABs are difficult to produce in the laboratory, genetically engineered plants are likely to find wide application in the production of human MABs.
Sixty-percentage acreage under soyabean in US has now Genetically engineered soyabean. The total acreage under genetically engineered crops around the world exceeds 100 million acres today.
Tissue culture: Tissue culture of both plant and animal cells. These are used for Micro propagation of elite or exotic materials (Such as orchids), production of useful compounds such as taxol (the widely used anti-cancer drug) and vanillin, and preparation in the laboratory of “natural” tissues such as arteries for arterial graft or skin for burn victims. (Modern tissue culture technologies allow the multiplication in the laboratory of cells isolated from plants and animals. In the case of plants, one can grow in the lab a whole plant from a single cell.)Stem cell techniques: Which would involve purification and isolation of stem cells from various tissues and develop into the desired tissue which could then be used, for example, for transplantation. Stem cells can be either totipotent (have the capability to produce any desired cell type or organ of the body under specific conditions) or they could be pluripotent (able to develop into several though not all cell types or organs). As embryonic stem cells are more likely totipotency than stem cells from adult tissues, the immediate emphasis in the area of stem cells is going to be first in the direction of establishing cell lines derived from early human embryos, from which stem cells could be isolated.Enzyme engineering and technology: Involves immobilized or stabilized enzymes, new classes of enzymes (ribozymes) or new enzymatic routes that produce important organic compounds. Enzymes are biological catalysts (Generally proteins) poised to replace inorganic catalysts, which are used in chemical industry. (Proteins are abundant biological entities made up of twenty amino acids strung together like pearls in a necklace, by a special type of thread- a chemical bond called the peptide bond. One protein differs from another in the total number of amino acids and their sequence in the chain.)Photosynthetic efficiency: Increasing photosynthetic efficiency for biomass production in the plant with the same amount of light and other inputs.New DNA technologies: These include DNA fingerprinting, sequencing of genomes, development and use of new molecular markers for plant identification and characterization. Also the development of DNA- based probes for diagnosis of inherited disorders, antisense technologies that are aimed at blockage of the function of a particular stretch of DNA and computing using DNA.Plant-based drugs: Use of modern biological techniques for validation, standardization and manufacture of indigenous plant-based drug formulations.Peptide synthesis: Synthasis to make new drugs or other materials of industrial and commercial importance, such as salmon GnRH analogue (Ovaprim) to induce ovulation in fish. (Peptides are small proteins, generally containing less than 50 amino acid moieties.)
The coming together of biotechnology and informatics is paying rich dividends. Genome projects, drug design and molecular taxonomy are all becoming increasingly dependent on informatics.
Rational drug design: Until a decade or so ago, the only way to discover a new drug was to synthesize a large number of compounds hoping that one of them will be effective against a particular disease. And it cost something between half a billion to a billion dollars for bringing a new drug to the market. As a result we have not added more than ten new drugs per year to the repertoire of medicines already available. In rational drug design, we first identify the molecular target we wish to attack. To do so, it becomes necessary to understand the mechanism of causation of the disease. Once we understand this mechanism and identify the molecular target lead effective computerized programs to design a molecule, which would hit the target. This approach of designing a drug on a rational basis cuts the cost of discovery of a new and reduces the time required (Now 12-15 years) by half.Nutraceuticals: That helps recovery after surgery or an episode of a major disease, or helps protect one against certain medical and health problems. For example, a Swedish company, Probi, has isolated a strain of Lactobacillus planetarum, which is apparently present in the digestive tract of Europeans and Amercians. (Indians have not yet been tested for its presence). The presence of this organism has been correlated with the ability of the person to recover after major surgery or after chemotherapy of cancer; this organism also seems to protect people against a vast range of stomach disorders including stomach ulcerts, irritable bowel syndrome and constipation. Probi is, therefore, marketing this organism in various forms, including a delicious soft drink!Assisted reproductive technologies: Such as artificial insemination (Using husband’s or donor semen), invitro fertilization, intra cytoplasmic sperm injection and techniques involving egg donation, surrogate motherhood or embryo transfer.New cloning technologies: - Cloning of genetically engineered animals that would produce useful products.Organ transplantation: Xenotransplantation that is transplantation into humans of organs from other animals. It appears that pig may be the most suitable for this biochemically, anatomically and immunologically. The major problem in xenotransplantation is the hyper-acute immunological rejection of the “ foreign organ” which occurs in a matter of minutes in enotrans plantation. This problem has been recently overcome by identifying the molecular basis of the hyper-acute rejection and then genetically engineering a pig to avoid it. But in the case of a kidney transplant from one human donor to another human recipient (homotransplantation) this does not occur. New drug-delivery systems: Such as lipsomes and electrical patches, and the use of circadian rhythms to optimize the effectiveness of the drug. Thus the drug may depending on the circadian rhythm of the individual will be effective when taken at noon and midnight, than if taken at 6 AM and 6 PM.Production of useful materials: Existing (for example, polyunsaturated fatty acids or beta-carotene, both of which are essential for normal vision) or new, from so far unutilized or under utilized but widely available resources such as marine organisms.
Production of new materials using new ideas: Observations or research findings, such as bacterial ropes or biodegradable polymers. For example, bacterial ropes that essentially consist of certain mutant bacteria that have the ability to grow into spagetti-like structures, when impregnated with certain metal ions can be stronger than steel but much lighter and biodegradable.DNA vaccines: Which would be much cheaper than protein antigen-based vaccines that are generally used today.New medical diagnostic technologies: - such as combination of MRI and Pet-SCAN for correlation of structure and function in normal and diseased individuals.Biosensor: For example, optical sensors using special thin films for detection of bacteria.Use of microbes: Microbes selected or genetically engineered for effecting chemically difficult transformations, for example in the field of steroids that are widely used as drugs.Bioremediadtion: For example of effluents or waste, using biological systems. A septic tank and an oxidation pond are simple examples of such bioremediation. Production of biogas is value-added bioremediation!Processing of low-grade ores using microorganisms: Commercially viable bio processes are available today for processing such ores of over a dozen metals.
Bioinformatics, including genomics and proteomics: This newly emerging area makes use of the enormous amount of data on biological systems that are becoming available. There are several million species known. The sequence of the building blocks of DNA of just one human being alone will fill nearly 700 books (typed single space) of 500 pages each.Nanobiotechnology: In which the operating or useful unit is of the scale of, say, a nanometre (millionth of a millimeter).
The cost of products produced through a biotechnological process is always less than that produced through a chemical synthetic route.
Biological warfare: This is defined as the ’employment of biological agents to produce casualties in man or animals or damage to plants. While a biological attack could result in a made-made epidemic of unprecedented scale, the classical principles of clinical medicine and epidemiology would apply. Prompt diagnosis and early interventions could reduce morbidity and mortality, and mitigate the effects of a biological attack.Advantages of biotechnologies
Biotechnologies are always non-polluting and, often, labour intensive. They make use of replenishable natural resources and help their conservation. They help, directly or indirectly, in saving energy. The cost of products produced through a biotechnological process is almost always less than that of the same product product produced, say, through a chemical synthetic route.Biotechnologies are less accident-prone. In spite of their high level of intellectual sophistication, it is easier to train people to handle biotechnologies than other technologies. Above all, they are interesting and exciting for all those involved with them.The Indian advantageNo other country in the world today has the unique set of advantages that India offers for large-scale practice of biotechnology. We have one of the largest bio in the world. We also have one of the largest coastlines anywhere. We have at least seven distinct climatic zones and one of the largest and most varied sets of marine organisms anywhere. The ambient temperature in most parts of the country is just what living organisms need for their activities that result in a biotechnological product. This curtails immensely the cost of cooling or heating which becomes obligatory for the practice of biotechnology in most parts of the Western world. There are places on the Indian coast where there is uninterrupted sunshine for some 340 days in the year so that one can grow marine organisms in open raceways.We have an enviable infrastructure and a large pool of trained manpower, with experience in most of the areas of biotechnology. Our labor and infrastructure costs are, perhaps, lower than anywhere else where biotechnology can be done and is being done, with the possible exception of China. We have large tracts of land available for growing the desired plants required for agriculture-based biotechnology. We have experience of building world-class institutions in virtually every sector of human endeavor – from outstanding basic research to efficient industrial production. We have, of course, many problems but we also know how to overcome them. In a nutshell the advantages far outweigh the disadvantages. It is a pity that we started much later in biotechnology than we could have but, even now, the prospects for the future are bright.

IPTV

2007-05-14T09:44:00.001+05:30

IPTV (Internet Protocol Television) is a system where a digital television service is delivered using the Internet Protocol over a network infrastructure, which may include delivery by a broadband connection. For residential users, IPTV is often provided in conjunction with Video on Demand and may be bundled with Internet services such as Web access and VoIP. The commercial bundling of IPTV, VoIP and Internet access is referred to as a Triple Play. Adding the mobile voice service leads to the Quadruple Play denomination. IPTV is typically supplied by a broadband operator using a closed network infrastructure. This closed network approach is in competition with the delivery of TV content over the public Internet. This type of delivery is widely called TV over Internet or Internet Television. In businesses, IPTV may be used to deliver television content over corporate LANs and business networks. Perhaps a simpler definition of IPTV would be television content that, instead of being delivered through traditional formats and cabling, is received by the viewer through the technologies used for computer networks.
Contents[hide]
1 History
2 Architecture
3 Protocols
4 Advantages
4.1 Interactivity
4.2 VoD
4.3 Better compression
4.4 Triple Play
4.5 IPTV based Converged Services
5 Limitations
6 See also
7 External links
//

[edit] History
In 1994, ABC's World News Now was the first television show to be broadcast over the Internet, using the CU-SeeMe videoconferencing software.
Internet radio company AudioNet started the first continuous live webcasts with content from WFAA-TV in January, 1998 and KCTU-LP on January 10, 1998.[1] [2][3]
In the past, this technology has been restricted by low broadband penetration. In the coming years, however, residential IPTV is expected to grow at a brisk pace as broadband was available to more than 200 million households worldwide in the year 2005, projected to grow to 400 million by the year 2010. Many of the world's major telecommunications providers are exploring IPTV as a new revenue opportunity from their existing markets and as a defensive measure against encroachment from more conventional Cable Television services. In the mean time, there are thousands of IPTV installations within schools, corporations, and other institutions that do not require the use of wide area connectivity.
As a result of the emergence of IPTV as an industry in its own right, dedicated trade shows and conferences have followed suit, such as IPTV World Forum Eastern Europe.

[edit] Architecture
Broadcast IPTV has two major architecture forms: free and fee based. As of June 2006, there are over 1,300 free IPTV channels available. This sector is growing rapidly and major television broadcasters worldwide are transmitting their broadcast signal over the Internet. These free IPTV channels require only an Internet connection and an Internet enabled device such as a personal computer, HDTV connected to a computer or even a 3G cell/mobile phone to watch the IPTV broadcasts. See also: Internet television Mobile TV
In December 2005, independently produced mariposaHD became the first original IPTV broadcast available in an HDTV format. Various Web portals offer access to these free IPTV channels. Some cite the ad-sponsored availability of TV series such as Lost and Desperate Housewives as indicators that IPTV will become more prevalent.
Because IPTV uses standard networking protocols, it promises lower costs for operators and lower prices for users. Using set-top boxes with broadband Internet connections, video can be streamed to households more efficiently than current coaxial cable. ISPs are upgrading their networks to bring higher speeds and to allow multiple High Definition TV channels.
In 2006, AT&T launched its U-Verse IPTV service. Comprised of a national head end and regional video serving offices, AT&T offered over 300 channels in 11 cities with more to be added in 2007 and beyond. While using IP protocols, AT&T has built a private IP network exclusively for video transport.
Local IPTV, as used by businesses for Audio Visual AV distribution on their company networks is typically based on a mixture of: a) Conventional TV reception equipment and IPTV encoders b) IPTV Gateways that take broadcast MPEG channels and IP wrap them to create multicast streams.
IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software (much like a cable or DSS box) that can handle viewer requests to access to many available media sources.

[edit] Protocols
IPTV covers both live TV (multicasting) as well as stored video (Video on Demand VOD). The playback of IPTV requires either a personal computer or a "set-top box" connected to a TV. Video content is typically compressed using either a MPEG-2 or a MPEG-4 codec and then sent in an MPEG transport stream delivered via IP Multicast in case of live TV or via IP Unicast in case of Video on Demand. IP Multicast is a method in which information can be sent to multiple computers at the same time. The newly released (MPEG4) H.264 codec is increasingly used to replace the older MPEG2 codec.
In standards-based IPTV systems, the primary underlying protocols used for:
Live TV is using IGMP version 2 for connecting to a multicast stream (TV channel) and for changing from one multicast stream to another (TV channel change).
VOD is using the Real Time Streaming Protocol (RTSP).
Currently, the only alternatives to IPTV are traditional TV distribution technologies such as terrestrial, satellite and cable. However, cable can be upgraded to two-way capability and can thus also carry IPTV.
NPVR (network-based Private Video Recorder)
Network Personal Video Recording is a consumer service where real-time broadcast television is captured in the network on a server allowing the end user to access the recorded programs on the schedule of their choice, rather than being tied to the broadcast schedule. The NPVR system provides ultimate time-shifted viewing of broadcast programs, allowing subscribers to record and watch programs at their convenience, without the added expense and maintenance needed for a hard drive-equipped set-top box. It's like having a PVR built into the network. In this way, services usually provided by popular consumer electronics hardware can be offered as network services. Subscribers can watch what they want, when they want, without needing yet another device or remote control.

[edit] Advantages
The IP-based platform offers significant advantages, including the ability to integrate television with other IP-based services like high speed Internet access and VoIP.
A switched IP network also allows for the delivery of significantly more content and functionality. In a typical TV or satellite network, using broadcast video technology, all the content constantly flows downstream to each customer, and the customer switches the content at the set-top box. The customer can select from as many choices as the telecomms, cable or satellite company can stuff into the “pipe” flowing into the home.
A switched IP network works differently. Content remains in the network, and only the content the customer selects is sent into the customer’s home. That frees up bandwidth, and the customer’s choice is less restricted by the size of the “pipe” into the home. This also implicates that the customer's privacy could be compromised to a greater extent than is possible with traditional TV or satellite networks.

[edit] Interactivity
An IP-based platform also allows significant opportunities to make the TV viewing experience more interactive and personalized. The supplier may, for example, include an interactive program guide that allows viewers to search for content by title or actor’s name, or a picture-in-picture functionality that allows them to “channel surf” without leaving the program they’re watching. Viewers may be able to look up a player’s stats while watching a sports game, or control the camera angle. They also may be able to access photos or music from their PC on their television, use a wireless phone to schedule a recording of their favorite show, or even adjust parental controls so their child can watch a documentary for a school report, while they’re away from home.

[edit] VoD
VoD stands for Video on Demand. VoD permits a customer to browse an online movie catalogue, to watch trailers and to select the movie he wants to watch. The playout of the selected movie starts nearly instantaneously on the customer's TV or PC.
Technically, when the customer selects the movie, a point-to-point unicast connection is set up between the customer's decoder (SetTopBox or PC) and the delivering streaming server. The signalling for the trick play functionality (pause, slow-motion, wind/rewind etc.) is assured by RTSP (Real Time Streaming Protocol).
The most common codecs used for VoD are MPEG-2, MPEG-4 and VC-1.
In order to avoid content piracy, the VoD content (the movies) is generally encrypted.

[edit] Better compression
IPTV uses a more efficient compression standard than Free-To-Air digital television, resulting in lower bit rates for streams, but higher compression may result in lower quality TV pictures in some instances.

[edit] Triple Play
Traditionally, TV has come down one wire cable TV or a terrestrial antenna, the telephone has used another (the Plain old telephone service), and the Internet has been available on either. Both cable operators and telco operators are starting to offer all three on one wire, which is more cost effective. Triple play is an expression used by service operators describing a bundle of telephony, data and video via a single connection. Triple play also refers to the combination of three services (typically Video, Voice and Internet) bundled together to entice customers to purchase all three products at a reduced rate. A quad play bundle usually includes a wireless component.

[edit] IPTV based Converged Services
Another advantage of an IP-based network is the opportunity for integration and convergence. Converged services implies interaction of existing services in a seamless manner to create new value added services. One good example is On-Screen Caller ID, getting Caller ID on your TV and the ability to handle it (send it to voice mail, etc). IP-based services will help to enable efforts to provide consumers anytime-anywhere access to content over their televisions, PCs and cell phones, and to integrate services and content to tie them together. Within businesses and institutions, IPTV eliminates the need to run a parallel infrastructure to deliver live and stored video services.

[edit] Limitations
Because IPTV is based on the Internet Protocol, it is sensitive to packet loss and delays if the IPTV connection is not fast enough

IPTV

2007-05-14T09:44:00.000+05:30

What Is An Ethernet Card?

2007-05-10T09:55:00.000+05:30

An Ethernet card is one kind of network adpter . These adapters support the Ethernet standard for high-speed network connections via cables. Ethernet cards are sometimes known as network interface cards (NICs).
Ethernet cards are available in several different standard packages called form factors:
Years ago, large ISA cards were the first standard for PCs, requiring users to open their computer case for installation.
Newer Ethernet cards installed inside desktop computers use the PCIstandard and are usually installed by the manufacturer.
Smaller PCMCIA Ethernet cards that resemble credit cards are readily available for laptop and other mobile computers.

These insert conveniently into slots on the side or front of the device.
Though they look more like small boxes than cards, external USB Ethernet adapters also exist. These are a convenient alternative to PCI cards for desktop computers and also commonly used with video game consoles and other consumer devices lacking PCMCIA slots.
Ethernet cards may operate at different network speeds depending on the protocol standard they support. Old Ethernet cards were capable only of the 10 Kbps Mbps[/link] maximum speed offered by Ethernet originally. Modern Ethernet adapters all support the 100 Mbps FAST Ethernet standard and an increasing number now also offer Gigabit Ethernet support at 1 Gbps (1000 Mbps).
An Ethernet adapter does not directly support WiFi wireless networking, but home network broadband routers contain the necessary technology to allow Ethernet devices to connect via cables.

How to hack(The Fundamental Techniques Of Serious Hacking)

2007-05-07T13:47:00.000+05:30

Hacking is the art of creative problem solving, whether used to find an unconventional solution to a difficult problem or to exploit holes in sloppy programming. Many people call themselves hackers, but few have the strong technical foundation that a hacker needs to be successful. Hacking: The Art Of Exploitation explains things that every real hacker should know.
While many hacking books show you how to run other people's exploits without really explaining the technical details, Hacking: The Art Of Exploitation introduces you to the spirit and theory of hacking as well as the science behind it all. By learning some of the core techniques and clever tricks of hacking, you will begin to understand the hacker mindset. Once you learn to think like a hacker, you can write your own hacks and innovate new techniques, or you can thwart potential attacks on your system

The content of Hacking moves between programming, networking, and cryptography. While well explained, it is a technical piece; some C programming experience is essential, although a basic understanding of networking and cryptography helps as well.
While Hacking is packed with technically accurate, detailed information, it is still a basic introduction to the subject of computer security. Hacking also does not use any notable measure of real-world examples; discussions rarely bring up specific worms and exploits that had previously existed, such as the PNG library overflows or the Blaster worm and related RPC service overflow. Thus, an inexperienced reader may not immediately make the connection between the theory and the reality of attack.

[edit] Programming
The programming portion of Hacking makes up over half of the book's total content. This section goes into the development, design, construction, and testing of exploit code, and thus involves some basic assembly programming. The demonstrated attacks range from simple buffer overflows on the stack to complex techniques involving overwriting the global offset table.
While Erickson discusses some countermeasures such as a non-executable stack and how to evade them with return-to-libc attacks, he does not dive into deeper matters without known guaranteed exploits such as address space layout randomization. Most protections afforded by the Openwall, GrSecurity, and PaX projects appear to be out of scope for Hacking; as do kernel exploits.
It has been suggested that Hacking be used to teach "basic computer programming fundamentals" in one review included in the opening pages of the book. Although these reviews are placed in the text for marketing purposes, the programming section of the book is technically accurate and does convey a lot of information not taught in typical introductory computer programming classes. Whether its use as a fundamental teaching tool would lead to more security-conscious and security-competent programmers overall is, however, neither studied nor proven.

[edit] Networking
The networking segment of Hacking has control of less than half of the remaining text. It explains the basics of the OSI model and basic networking concepts; packet sniffing; connection hijacking; denial of service; and port scanning.
Although technically accurate, the networking section of Hacking only serves as a basic introduction to network security. Countermeasures such as complex firewalls; Stateful Packet Inspection; network address translation, the threat of firewalking, and countermeasures thereof; intrusion detection and prevention; and virtual private networks are not discussed.

[edit] Cryptology
The cryptology section of Hacking consumes the rest of the book's pages. This is another bottom-up section, starting off with basic information theory and moving through symmetric and asymmetric encryption. It winds out in cracking WEP utilizing the Fluhrer, Mantin, and Shamir Attack.
This section appears to be miscellaneous information for the aspiring cryptology scholar. Besides the basics, including man-in-the-middle attacks, dictionary attacks, and the use of John the Ripper; Hacking discusses quantum key distribution, Lov Grover's Quantum Search Algorithm, and Peter Shor's Quantum Factoring Algorithm for breaking RSA encryption using a very large quantum computer.

Virtual hosting a power full concept

2007-05-01T13:16:00.000+05:30

Virtual hosting is a method that servers such as webservers use to host more than one domain name on the same computer, sometimes on the same IP address.
There are two basic methods of accomplishing virtual hosting: name-based, and IP address or ip-based.
Contents[hide]
1 Name based
1.1 Cons
2 IP address based
3 Uses
4 See also
//

[edit] Name based
Name based virtual hosts use multiple host names for the same webserver IP address.
With web browsers that support HTTP/1.1 (as most do), upon connecting to a webserver, the browsers send the address that the user typed into their browser's address bar (the URL). The server can use this information to determine which web site, as well as page, to show the user. The browser specifies the address by setting the Host HTTP header with the host specified by the user. The Host header is required in all HTTP/1.1 requests.
For instance, a server could be receiving requests for two domains, www.site1.com and www.site2.com, both of which resolve to the same IP address. For www.site1.com, the server would send the HTML file file from the directory /www/JoeUser/site/, while requests for www.site2.com would make the server serve pages from /www/FrankUser/site/.

[edit] Cons
If the Domain Name System (DNS) is not properly functioning, it becomes much harder to access a virtually-hosted website. Ordinarily, in this case, the user could try and fall back to using the IP address to contact the system, as in http://12.34.56.78/. However, the web browser doesn't know what hostname to send when this happens, so the server will respond with a default website—often not the site the user expects. This workaround is not really useful for an average web user, but may be of some use to a site administrator while fixing DNS records.
A workaround in this case is to add the IP address and hostname to the client system's hosts file. At this point, accessing the server with the domain name should work again. However, users should be careful when doing this, as any changes to the true mapping between hostname and IP address will be overridden by the local setting.
Another issue with virtual hosting is the inability to host multiple secure websites running Secure Sockets Layer or SSL. Because the SSL handshake takes place before the expected hostname is sent to the server, the server doesn't know which encryption key to use when the connection is made. One workaround is to run multiple web server programs, each listening to a different incoming port, which still allows the system to just use a single IP address. If running multiple web server programs is considered clumsy, a more efficient solution is to select TLS (TLS 1.1 or later, which enables name-based virtual hosting as of December 2006). Another option is to do IP aliasing, where a single computer listens on more than one IP address.

[edit] IP address based
In IP based virtual hosting, each site (either a dns hostname or a group of dns hostnames that act the same) points to a unique IP address. The webserver is configured with multiple physical network interfaces, virtual network interfaces on the same physical interface or multiple IP addresses on one interface.
The webserver can obtain the address the TCP connection was intended for using a standard api and uses this to determine which website to serve. The client is not involved in this process and therefore (unlike with name based virtual hosting) there are no compatibility issues.

[edit] Uses
Virtual web hosting is often used on large scale in companies whose business model is to provide low cost website hosting for customers. The vast majority of such web hosting service customer websites worldwide are hosted on shared servers, using virtual hosting technology.
Many businesses utilize virtual servers for internal purposes, where there is a technology or administrative reason to keep several separate websites such as customer extranet website, employee extranet, internal intranet, intranets for different departments. If there are not security concerns in the website architectures, they can be merged into a single server using virtual hosting technology, which reduces management and administrative overhead and the number of separate servers required to support the business.

[edit] See also
Virtual private server
Shared web hosting service
Retrieved from "http://en.wikipedia.org/wiki/Virtual_hosting"

Want to Work at NASA?

2007-04-30T14:24:00.000+05:30

NASA is more than astronauts. We are scientists, engineers, computer programmers, personnel specialists, accountants, writers, maintenance workers and many, many other kinds of people. At the NASAJobs Web site, you can review job listings, post a resume and even apply for a NASA job online.
At NASAJobs students can find opportunities for internships, cooperative programs and summer employment.
For all the diversity of NASA's workforce, the question, "How can I become an astronaut?" is very common. The answer depends on where you are now and where you want to go.
If you haven't finished high school yet, former astronaut Dr. Sally K. Ride has these suggestions for you:
"The most important steps that I followed were studying math and science in school. I was always interested in physics and astronomy and chemistry, and I continued to study those subjects through high school and college on into graduate school. That's what prepared me for being an astronaut; it actually gave me the qualifications to be selected to be an astronaut. I think the advice that I would give to any kids who want to be astronauts is to make sure that they realize that NASA is looking for people with a whole variety of backgrounds: they are looking for medical doctors, microbiologists, geologists, physicists, electrical engineers. So find something that you really like and then pursue it as far as you can and NASA is apt to be interested in that profession."

Detail of VOIP

2007-04-27T10:06:00.000+05:30

Functionality
VoIP can facilitate tasks that may be more difficult to achieve using traditional networks:
Incoming phone calls can be automatically routed to your VoIP phone, regardless of where you are connected to the network. Take your VoIP phone with you on a trip, and wherever you connect to the Internet, you can receive incoming calls.
Free phone numbers for use with VoIP are available in the USA, UK and other countries from organizations such as VoIP User.
Call center agents using VoIP phones can work from anywhere with a sufficiently fast and stable Internet connection.
Many VoIP packages include PSTN features that most telcos (telecommunication companies) normally charge extra for, or may be unavailable from your local telco, such as 3-way calling, call forwarding, automatic redial, and caller ID.

[edit] Mobility
VoIP allows users to travel anywhere in the world and still make and receive phone calls:
Subscribers of phone-line replacement services can make and receive local phone calls regardless of their location. For example, if a user has a New York City phone number and is traveling in Europe and someone calls the phone number, it will ring in Europe. Conversely, if a call is made from Europe to New York City, it will be treated as a local call. Of course, there must be a connection to the Internet e.g. WiFi to make all of this possible.
Users of Instant Messenger based VoIP services can also travel anywhere in the world and make and receive phone calls.
Specialized mobile VoIP services enable users to talk over internet protocol and use VoIP based Instant Messenger services from their mobile phones.
VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.

[edit] Drawbacks

[edit] Difficulty with sending faxes
One drawback is the difficulty in sending faxes due to software and networking constraints in most of the home systems. An effort is underway to remedy this by defining an alternate IP-based solution for delivering Fax-over-IP, namely the T.38 protocol. Another possible solution to overcome the drawback is to treat the fax system as a message switching system which does not need real time data transmission - such as sending a fax as an email attachment (see iFax) or remote printout (see Internet Printing Protocol). The end system can completely buffer the incoming fax data before displaying or printing the fax image.

[edit] Internet connection requirement
Another drawback of VoIP service is its reliance upon another separate service - an Internet connection. The quality and overall reliability of the phone connection is entirely reliant upon the quality, reliability, and speed of the Internet connection which it is using. Shortcomings with Internet connections and Internet Service Providers (ISPs) can affect VoIP calls. Higher overall network latencies can lead to significantly reduced call quality and cause certain problems such as echoing. Certain providers, such as Time Warner Cable, offer a Voice over IP product to their customers without requiring an Internet service.
VoIP is not entirely reliant upon internet connections, however. VoIP systems can also utilize regular telephone lines and business-grade connections like T1 for voice service.[citation needed] A few business VoIP providers offer dedicated point-to-point T1 connections, not relying on an Internet connection for service. Although residential VoIP service typically uses only an Internet connection, business-grade VoIP service can use a variety of connection methods to provide ongoing phone service.
Many VoIP users still maintain a traditional analog voice line (business line) which allows them to dial emergency numbers and utilize a traditional fax machine.

[edit] Power outages
Another drawback of VoIP is the likely inability to make phone calls during a power outage, though this problem is shared with some conventional phones which require more power than the landline itself can supply.[2] Cordless phone units in particular are more affected by power outages as many do not have a battery backup option for the base station. This can be remedied with a battery backup like an Uninterruptible Power Supply. During a power outage one also has the choice to forward calls to a cell phone or alternate number.
If VoIP is used in solitary LAN (with no Internet connection), it would consume more resources compared to a PABX.[citation needed]
Modems are now available with lithium ion battery backup so the service can be used with no external power.[citation needed]

[edit] Implementation
Because UDP does not provide a mechanism to ensure that data packets are delivered in sequential order, or provide Quality of Service guarantees, VoIP implementations face problems dealing with latency and jitter. This is especially true when satellite circuits are involved, due to long round trip propagation delay (400 milliseconds to 600 milliseconds for geostationary satellite). The receiving node must restructure IP packets that may be out of order, delayed or missing, while ensuring that the audio stream maintains a proper time consistency. This functionality is usually accomplished by means of a jitter buffer.
Another challenge is routing VoIP traffic through firewalls and address translators. Private Session Border Controllers are used along with firewalls to enable VoIP calls to and from a protected enterprise network. Skype uses a proprietary protocol to route calls through other Skype peers on the network, allowing it to traverse symmetric NATs and firewalls. Other methods to traverse firewalls involve using protocols such as STUN or ICE.
VoIP challenges:
Delay/Network Latency
Packet loss
Jitter
Echo
Security
Fixed delays cannot be controlled but some delays can be minimized by marking voice packets as being delay-sensitive (see, for example, Diffserv).
The principal cause of packet loss is congestion, which can be controlled by congestion management and avoidance. Carrier VoIP networks avoid congestion by means of traffic engineering.
Variation in delay is called jitter. The effects of jitter can be mitigated by storing voice packets in a buffer (called a play-out buffer) upon arrival, before playing them out. This avoids a condition known as buffer underrun, in which the playout process runs out of voice data to play because the next voice packet has not yet arrived, but increases delay by the length of the buffer.
Common causes of echo include impedance mismatches in analog circuitry, and acoustic coupling of the transmit and receive signal at the receiving end.

[edit] Reliability
Conventional phones are connected directly to telephone company phone lines, which in the event of a power failure are kept functioning by back-up generators or batteries located at the telephone exchange. However, household VoIP hardware uses broadband modems and other equipment powered by household electricity, which may be subject to outages dictating the use of an uninterruptible power supply or generator to ensure availability during power outages. Early adopters of VoIP may also be users of other phone equipment, such as PBX and cordless phone bases, that rely on power not provided by the telephone company. Even with local power still available, the broadband carrier itself may experience outages as well. While the PSTN has been matured over decades and is typically extremely reliable, most broadband networks are less than 10 years old, and even the best are still subject to intermittent outages. Furthermore, consumer network technologies such as cable and DSL often are not subject to the same restoration service levels as the PSTN or business technologies such as T-1 connection.

[edit] Quality of Service
Some broadband connections may have less than desirable quality. Where IP packets are lost or delayed at any point in the network between VoIP users, there will be a momentary drop-out of voice. This is more noticeable in highly congested networks and/or where there is long distances and/or interworking between end points. Technology has improved the reliability and voice quality over time and will continue to improve VoIP performance as time goes on.
It has been suggested to rely on the packetized nature of media in VOIP communications and transmit the stream of packets from the source phone to the destination phone simultaneously across different routes (multi-path routing). In such a way, the temporary failures have less impact on the communication quality. In capillary routing it has been suggested to use at the packet level Fountain codes or particularly raptor codes for transmitting extra redundant packets making the communication more reliable.
A number of protocols have been defined to support the reporting of QoS/QoE for VoIP calls. These include RTCP XR (RFC3611), SIP RTCP Summary Reports, H.460.9 Annex B (for H.323), H.248.30 and MGCP extensions. The RFC3611 VoIP Metrics block is generated by an IP phone or gateway during a live call and contains information on packet loss rate, packet discard rate (due to jitter), packet loss/discard burst metrics (burst length/density, gap length/density), network delay, end system delay, signal / noise / echo level, MOS scores and R factors and configuration information related to the jitter buffer.
RFC3611 VoIP metrics reports are exchanged between IP endpoints on an occasional basis during a call, and an end of call message sent via SIP RTCP Summary Report or one of the other signaling protocol extensions. RFC3611 VoIP metrics reports are intended to support real time feedback related to QoS problems, the exchange of information between the endpoints for improved call quality calculation and a variety of other applications.

[edit] Emergency calls
The nature of IP makes it difficult to locate network users geographically. Emergency calls, therefore, cannot easily be routed to a nearby call center, and are impossible on some VoIP systems. Sometimes, VoIP systems may route emergency calls to a non-emergency phone line at the intended department. In the US, at least one major police department has strongly objected to this practice as potentially endangering the public.[3]
Moreover, in the event that the caller is unable to give an address, emergency services may be unable to locate them in any other way. Following the lead of mobile phone operators, several VoIP carriers are already implementing a technical work-around. For instance, one large VoIP carrier requires the registration of the physical address where the VoIP line will be used. When you dial the emergency number for your country, they will route it to the appropriate local system. They also maintain their own emergency call center that will take non-routable emergency calls (made, for example, from a software based service that is not tied to any particular physical location) and then will manually route your call once learning your physical location.
The United States government had set a deadline, requiring VoIP carriers to implement E911; however, the deadline is being appealed by several of the leading VoIP companies.
This is a different situation with IPBX systems, where these corporate systems often have full E911 capabilities built into the system.[citation needed]

[edit] Integration into global telephone number system
While the traditional Plain Old Telephone System (POTS) and mobile phone networks share a common global standard (E.164) which allocates and identifies any specific telephone line, there is no widely adopted similar standard for VoIP networks. Some allocate an E.164 number which can be used for VoIP as well as incoming/external calls. However, there are often different, incompatible schemes when calling between VoIP providers which use provider specific short codes.

[edit] Single point of calling
With hardware VoIP solutions it is possible to connect the VoIP router into the existing central phone box in the house and have VoIP at every phone already connected. Software based VoIP services require the use of a computer, so they are limited to single point of calling, though handsets are now available, allowing them to be used without a PC. Some services provide the ability to connect WiFi SIP phones so that service can be extended throughout the premises, and off-site to any location with an open hotspot.[4]

[edit] Mobile phones & Handheld Devices
Telcos and consumers have invested billions of dollars in mobile phone equipment. In developed countries, mobile phones have achieved nearly complete market penetration, and many people are giving up landlines and using mobiles exclusively. Given this situation, it is not entirely clear whether there would be a significant higher demand for VoIP among consumers until either public or community wireless networks have similar geographical coverage to cellular networks (thereby enabling mobile VoIP phones, so called WiFi phones) or VoIP is implemented over legacy 3G networks. However, "dual mode" handsets, which allow for the seamless handover between a cellular network and a WiFi network, are expected to help VoIP become more popular.[5]
The first mobile VoIP solutions were Fring and Truphone. Phones like the Nokia E60, E61 have been the first "dual mode" handsets capable of delivering mobile VoIP. With more and more mobile phones and handheld devices using VOIP, the nicknames of "MoIP" and MVoip (Mobile VoIP)have been attributed to these mobile applications.
Handheld Devices are another type of medium whereby you can use VoIP services. Since most of these devices are limited to using GSM/GPRS type of communication mediums, almost all of the handheld devices use WiFi of some sort.
Another addition to handheld devices are ruggedized barcode type devices that are used in warehouses and retail environments. These type of devices rely on "inside the 4 walls" type of VoIP services that do not connect to the outside world and are solely to be used from employee to employee communications.

[edit] Security
The majority of consumer VoIP solutions do not support encryption yet. As a result, it is relatively easy to eavesdrop on VoIP calls and even change their content. There are several open source solutions that facilitate sniffing of VoIP conversations. A modicum of security is afforded due to patented audio codecs that are not easily available for open source applications, however such security through obscurity has not proven effective in the long run in other fields. Some vendors also use compression to make eavesdropping more difficult. However, real security requires encryption and cryptographic authentication which are not widely available at a consumer level.[6] The existing secure standard SRTP and the new ZRTP protocol is available on Analog Telephone Adapters(ATAs) as well as various softphones. It is possible to use IPsec to secure P2P VoIP by using opportunistic encryption. A notable softphone which does not use SRTP but uses strong encryption by default is Skype.
The Voice VPN solution provides secure voice for enterprise VoIP networks by applying IPSec encryption to the digitized voice stream.

[edit] Pre-Paid Phone Cards
VoIP has become an important technology for phone services to travelers, migrant workers and ex-pats, who either, due to not having a fixed or mobile phone or high overseas roaming charges, choose instead to use VoIP services to make their phone calls. Pre-paid phone cards can be used either from a normal phone or from Internet cafes that have phone services. Developing countries and areas with high tourist or immigrant communities generally have a higher uptake.

[edit] Caller ID
Caller ID support among VoIP providers varies, although the majority of VoIP providers now offer full Caller ID with name on outgoing calls. When calling a traditional PSTN number from some VoIP providers, Caller ID is not supported.
In a few cases, VoIP providers may allow a caller to spoof the Caller ID information, making it appear as though they are calling from a different number. Business grade VoIP equipment and software often makes it easy to modify caller ID information. Although this can provide many businesses great flexibility, it is also open to abuse.

[edit] Adoption

[edit] Mass-market telephony
A major development starting in 2004 has been the introduction of mass-market VoIP services over broadband Internet access services, in which subscribers make and receive calls as they would over the PSTN. Full phone service VoIP phone companies provide inbound and outbound calling with Direct Inbound Dialing. Many offer unlimited calling to the U.S., and some to Canada or selected countries in Europe or Asia as well, for a flat monthly fee.
These services take a wide variety of forms which can be more or less similar to traditional POTS. At one extreme, an analog telephone adapter (ATA) may be connected to the broadband Internet connection and an existing telephone jack in order to provide service nearly indistinguishable from POTS on all the other jacks in the residence. This type of service, which is fixed to one location, is generally offered by broadband Internet providers such as cable companies and telephone companies as a cheaper flat-rate traditional phone service. Often the phrase "VoIP" is not used in selling these services, but instead the industry has marketed the phrase "Internet Phone" or "Digital Phone" which is aimed at typical phone users who are not necessarily tech-savvy. Typically, the provider touts the advantage of being able to keep one's existing phone number.
At the other extreme are services like Gizmo Project and Skype which rely on a software client on the computer in order to place a call over the network, where one user ID can be used on many different computers or in different locations on a laptop. In the middle lie services which also provide a telephone adapter for connecting to the broadband connection similar to the services offered by broadband providers (and in some cases also allow direct connections of SIP phones) but which are aimed at a more tech-savvy user and allow portability from location to location. One advantage of these two types of services is the ability to make and receive calls as one would at home, anywhere in the world, at no extra cost. No additional charges are incurred, as call diversion via the PSTN would, and the called party does not have to pay for the call. For example, if a subscriber with a home phone number in the U.S. or Canada calls someone else within his local calling area, it will be treated as a local call regardless of where that person is in the world. Often the user may elect to use someone else's area code as his own to minimize phone costs to a frequently called long-distance number.
For some users, the broadband phone complements, rather than replaces, a PSTN line, due to a number of inconveniences compared to traditional services. VoIP requires a broadband Internet connection and, if a telephone adapter is used, a power adapter is usually needed. In the case of a power failure, VoIP services will generally not function. Additionally, a call to the U.S. emergency services number 9-1-1 may not automatically be routed to the nearest local emergency dispatch center, and would be of no use for subscribers outside the U.S. This is potentially true for users who select a number with an area code outside their area. Some VoIP providers offer users the ability to register their address so that 9-1-1 services work as expected.
Another challenge for these services is the proper handling of outgoing calls from fax machines, TiVo/ReplayTV boxes, satellite television receivers, alarm systems, conventional modems or FAXmodems, and other similar devices that depend on access to a voice-grade telephone line for some or all of their functionality. At present, these types of calls sometimes go through without any problems, but in other cases they will not go through at all. And in some cases, this equipment can be made to work over a VoIP connection if the sending speed can be changed to a lower bits per second rate. If VoIP and cellular substitution becomes very popular, some ancillary equipment makers may be forced to redesign equipment, because it would no longer be possible to assume a conventional voice-grade telephone line would be available in almost all homes in North America and Western-Europe. The TestYourVoIP website offers a free service to test the quality of or diagnose an Internet connection by placing simulated VoIP calls from any Java-enabled Web browser, or from any phone or VoIP device capable of calling the PSTN network.

[edit] Corporate and telco use
Although few office environments and even fewer homes use a pure VoIP infrastructure, telecommunications providers routinely use IP telephony, often over a dedicated IP network, to connect switching stations, converting voice signals to IP packets and back. The result is a data-abstracted digital network which the provider can easily upgrade and use for multiple purposes.
Corporate customer telephone support often use IP telephony exclusively to take advantage of the data abstraction. The benefit of using this technology is the need for only one class of circuit connection and better bandwidth use. Companies can acquire their own gateways to eliminate third-party costs, which is worthwhile in some situations.
VoIP is widely employed by carriers, especially for international telephone calls. It is commonly used to route traffic starting and ending at conventional PSTN telephones.
Many telecommunications companies are looking at the IP Multimedia Subsystem (IMS) which will merge Internet technologies with the mobile world, using a pure VoIP infrastructure. It will enable them to upgrade their existing systems while embracing Internet technologies such as the Web, email, instant messaging, presence, and video conferencing. It will also allow existing VoIP systems to interface with the conventional PSTN and mobile phones.
Electronic Numbering (ENUM) uses standard phone numbers (E.164), but allows connections entirely over the Internet. If the other party uses ENUM, the only expense is the Internet connection.

[edit] Use in Amateur Radio
Amateur radio has adopted VoIP by linking repeaters and users with Echolink, IRLP, D-STAR, Dingotel and EQSO. Echolink and IRLP are programs/systems based upon the Speak Freely VoIP open source software. In fact, Echolink allows users to connect to repeaters via their computer (over the Internet) rather than by using a radio. By using VoIP Amateur Radio operators are able to create large repeater networks with repeaters all over the world where operators can access the system with actual ham radios.
Ham Radio operators using radios are able to tune to repeaters with VoIP capabilities and use DTMF buttons to command the repeater to connect to various other repeaters, thus allowing them to talk to people all around the world, even with "line of sight" VHF radios.

[edit] Click to call
Main article: Click-to-call
Click-to-call is a service which lets users click a button and immediately speak with a customer service representative. The call can either be carried over VoIP, or the customer may request an immediate call back by entering their phone number. One significant benefit to click-to-call providers is that it allows companies to monitor when online visitors change from the website to a phone sales channel.

[edit] Legal issues in different countries
As the popularity of VoIP grows, and PSTN users switch to VoIP in increasing numbers, governments are becoming more interested in regulating[7] VoIP in a manner similar to legacy PSTN services, especially with the encouragement of the state-mandated telephone monopolies/oligopolies in a given country, who see this as a way to stifle the new competition.
In the U.S., the Federal Communications Commission now requires all VoIP operators who do not support Enhanced 911 to attach a sticker warning that traditional 911 services aren't available. The FCC recently required VoIP operators to support CALEA wiretap functionality. The Telecommunications Act of 2005 proposes adding more traditional PSTN regulations, such as local number portability and universal service fees. Other future legal issues are likely to include laws against wiretapping and network neutrality.
Some Latin American and Caribbean countries, fearful for their state owned telephone services, have imposed restrictions on the use of VoIP, including in Panama where VoIP is taxed. In Ethiopia, where the government is monopolizing telecommunication service, it is a criminal offense to offer services using VoIP. The country has installed firewalls to prevent international calls being made using VoIP. These measures were taken after a popularity in VoIP reduced the income generated by the state owned telecommunication company.
In the European Union, the treatment of VoIP service providers is a decision for each Member State's national telecoms regulator, which must use competition law to define relevant national markets and then determine whether any service provider on those national markets has "significant market power" (and so should be subject to certain obligations). A general distinction is usually made between VoIP services that function over managed networks (via broadband connections) and VoIP services that function over unmanaged networks (essentially, the Internet).
VoIP services that function over managed networks are often considered to be a viable substitute for PSTN telephone services (despite the problems of power outages and lack of geographical information); as a result, major operators that provide these services (in practice, incumbent operators) may find themselves bound by obligations of price control or accounting separation.
VoIP services that function over unmanaged networks are often considered to be too poor in quality to be a viable substitute for PSTN services; as a result, they may be provided without any specific obligations, even if a service provider has "significant market power".
The relevant EU Directive is not clearly drafted concerning obligations which can exist independently of market power (e.g., the obligation to offer access to emergency calls), and it is impossible to say definitively whether VoIP service providers of either type are bound by them. A review of the EU Directive is under way and should be complete by 2007.
In India, it is legal to use VoIP, but it is illegal to have VoIP gateways inside India. This effectively means that people who have PCs can use them to make a VoIP call to any number, but if the remote side is a normal phone, the gateway that converts the VoIP call to a POTS call should not be inside India.
In the UAE, it is illegal to use any form of VoIP, to the extent that websites of Skype and Gizmo Project don't work.
In the Republic of Korea, only providers registered with the government are authorized to offer VoIP services. Unlike many VoIP providers, most of whom offer flat rates, Korean VoIP services are generally metered and charged at rates similar to terrestrial calling. Foreign VoIP providers such as Vonage encounter high barriers to government registration. This issue came to a head in 2006 when internet service providers providing personal internet services by contract to United States Forces Korea members residing on USFK bases threatened to block off access to VoIP services used by USFK members of as an economical way to keep in contact with their families in the United States, on the grounds that the service members' VoIP providers were not registered. A compromise was reached between USFK and Korean telecommunications officials in January 2007, wherein USFK service members arriving in Korea before June 1, 2007 and subscribing to the ISP services provided on base may continue to use their U.S.-based VoIP subscription, but later arrivals must use a Korean-based VoIP provider, which by contract will offer pricing similar to the flat rates offered by U.S. VoIP providers. [1]

About VOIP

2007-04-27T09:47:00.000+05:30

Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network.
Companies providing VoIP service are commonly referred to as providers, and protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET providers. Some cost savings are due to utilizing a single network - see attached image - to carry voice and data, especially where users have existing underutilized network capacity that can carry VoIP at no additional cost. VoIP to VoIP phone calls are sometimes free, while VoIP to public switched telephone networks, PSTN, may have a cost that's borne by the VoIP user.
There are two types of PSTN to VoIP services: DID (Direct Inward Dialing) and access numbers. DID will connect the caller directly to the VoIP user while access numbers require the caller to input the extension number of the VoIP user. Access numbers are usually charged as a local call to the caller and free to the VoIP user while DID usually has a monthly fee.[1] There are also DIDs that are free to the VoIP user but chargeable to the caller.