The Internet has grown at a very rapid rate, and it only gets better by the day. Every device that's connected to the Internet (Let it be some high end Web Server, VoIP Switches, Your PC, that new sleeky looking iPhone you've fallen in love with or any other device you may imagine) needs to have some unique identity. Without an identity the device cannot communicate or receive any communication. Think of it as your house address, or perhaps your phone number - Its unique and your colleagues and peers use it to reach to you. In Internet terms, this unique address is referred to as the IP Address.
The current IP Addressing system allows to have roughly about 3.3 billion unique addresses. However, with the rapid growth of the Internet and the devices connecting to it, there are simply not enough addresses available to uniquely allocate to all. Now, that's a problem! Nevertheless, every problem has a good, or sometimes, not so good solution. So, the solution for the scarce IP Address problem? - NAT.
NAT is a mechanism of taking a unique IP address and sharing it with a pool of devices. You may despair, "Thats like sharing my house address with someone else!", or perhaps, "Thats like sharing my phone number with someone else!", well, in a sense, it's something like that, but its not that bad. Imagine your work place, not everyone has a unique/direct desk-phone number. You've got the primary phone number and employees have extensions. Your extension could be 1001, and your peers Tom, Dick and Harry could be having 1002, 1003, 1004 respectively. One important thing to note would be, your extension is not globally unique, some stranger in the next office could be having extension 1001, and many strangers in many parts of the world could be having the same extension number, but when you pair your company primary phone number with your extension (i.e. 212-777-3456 Ext: 1001) that's unique, and nobody else anywhere in the world could have the same pair at the same time with you...
Read more :http://www.redvoip.com
