Idea behind IP
As the term VoIP is associated with the term ‘IP’, we will discuss about IP or Internet Protocol in this section.When a computer gets connected with internet it gets assigned with an IP by its network administrator or ISP provider.
Guess, the operating system of your computer is Windows. DHCP (Dynamic host control protocol) is the default protocol for Windows IP connections. Using DHCP, the computer sends a special request for IP address to the ISP device which responds with an IP address.Each time the computer gets connected with internet, it gets a new IP address. These IP addresses are dynamic as it changed time to time.
If you need your computer uniquely identifiable over internet, you need to request your ISP to give you a static IP address. For example, a web hosting servers use a static IP address so that a web surfer can find it quickly.You are probably familiar with WiFi routers that you may use for your home internet connection. Routers are specially designed to enable multiple computers to share a single IP address. That’s why with a single router, several computers or laptops in your home get internet connection.
An IP address is 32-bit binary number with Internet Protocol Version 4 (IPv4) designed by Internet Engineering Task Force. That means there are thirty two 0s and 1s in an IP address. But to make an IP address in a human readable notation, this 32-bit are divided into 4 blocks (each block contain 8 bits).
Now if you convert each 8 bits (like 01100111) into decimal number then these values comes within the range of 0-255. That’s why, the IP address of your computer may look like 192.204.101.32; notice that each number 192, 204, 101 & 32 fall within the range of 0-255. If you do some math, then you will realize that IPv4 can provide around 232= 4 billion IP addresses. World wide increasing use of internet is keeping pressure on the availability of IPv4 addresses. By the end of year 2011, all available IPv4 address will be finished.
By keeping in mind this IPv4 exhaustion, IPv6 was develop in 1990s which is now in commercial deployment phase around the world. IPv6 uses 128 bit address (2128= 340 trillion trillion trillion…) to provide larger addressing capabilities than IPv4. For your information, there are 6.8 billion people living in 2010 all over the World. So, it is expected that trillions and trillions of IPv6 address will meet the demand of people for a long time.
But worldwide adoption of IPv6 address is difficult as IPv6 does not comply with IPv4 addressing. There need to be some gateway to communicate a new IPv6 device with conventional IPv4 devices in future.Another way to preserve IPv4 address has done by initiating Private IP address. This technique significantly delays IPv4 exhaustion. It is understandable that globally routable IP is not necessary for home, office and small enterprises that do not require serious functions to perform in internet. So, a single unique IP address can be use to connect an entire group of computers.
That’s why; Internet Assigned Numbers Authority (IANA) has reserved 3 ranges (class A. B & C) of IPV4 address for using in private networks.
- Class A range from 10.0.0.0 to 10.255.255 255
- Class B from 172.16.0.0 to 172.31.255.255
- Class C from 192.168.0.0 to 192.168.255.255
All the IP addresses fall within the range are not included with IP address registry and thus it will not rout over internet. If you think vice versa, all the IP address fall outside these classes are routed on the internet.
This discussion gives an answer to a common question. You may ask, when I traveled to China, I checked my laptop IP address: 192.168.101.32, which is similar to the IP address I get in my UK home; how does it possible?This is because, both internet provider in China & UK assign you an IP address from class C reserved IP that starts with 192.168; which turns as same IP address 192.168.101.32 whimsically.
But, having same IP address (like 192.168.101.32) will not affect your unique IP at all. Thousands of computers may have same private IP address in a given time. But connection of worldwide internet requires a registered IP address. Then how you are surfing on net every day using unregistered privates IP? Your internet service provider uses a registered IP address which is outside of reserved IP addresses for example 213.18.123.110. When your computer gets connected to the local ISP, it uses that registered IP address.
A NAT (Network Address Translator) router placed in the local ISP office helps to translate private IP address into the registered or public IP address of your ISP. So, through NAT, your laptop’s IP 192.168.101.32 is translated to 213.18.123.110 and gets connected with internet.