Internet to fall short of IPv4 Addresses soon

The word is out and it is official – Internet is going to fall short of IPv4 addresses in the next 500 days or odd. Computer experts and Industry leaders had expressed their warnings earlier but it seems they either fell on deaf ears or the IT Industry did not anticipate that the short fall would happen so early. What does this have in store for the IT Industry? Well, it clearly means that each device – every server, mobile phones, router or for that matter, everything else that makes up the Internet or uses the Internet will need to be reconfigured or upgraded. The upgrade will include a switch to IP Version 6 (IPv6) instead of the prevailing IP Version 4 (IPv4) which is now more than 20 years old. Here is a small explanation of the technicality involved that may help to understand for those who are non-technical.

What is an IP Address?

The Internet works on a transport system, commonly known as TCP/IP protocol, to transfer and exchange data. TCP stands for Transfer Control Protocol and IP stands for Internet Protocol. Both together make the TCP/IP protocol stack. An IP Address is basically an identifier for a computer or a device on a TCP/IP network. When one computer or device transfers or exchanges data to another, it uses the IP address of the destination. The transmitting computer or device is called the Source while the receiving one is called the Destination.

The format of the IP address that we currently use is a 32-bit numeric address written as four (4) numbers seperated by periods. For example, 192.168.4.2 is an IP Address. Each device or a computer connected directly to the Internet has to have a unqiue IP address. No two devices can use the same IP address as this would cause a conflict and the Source would not know which Destination to send the data to. Similary a Destination would not be able to identify which Source to report back to that the data has been received if there is an IP address conflict. Currently, the IP address range, ie. IP Version 4 or IPv4, is being classified in to 3 main classes: Class A, Class B and Class C. There are other classes too, but they are restricted. The art of this classification is called Subnetting which is further enhanced by Supernetting. Since explaining this involves lot of technical understanding of the TCP/IP Protocol Stack, we shall skip it for now. For those interested to know further, there is always Google at your help.

How does an IP work?

There is no better way to understand this but with an example. Let’s take the example of my website www.vishalvasu.com. My website is associated with an IP address since it works on the TCP/IP protocol. The IP address of my website is:

74.53.251.150

The above format is called a dotted decimal format which makes it easier for humans to remember. But we all know by now that computers and related devices communicate in a binary format. The same IP address to a computer or a device on the Internet would mean something like this:

01001010.00110101.11111011.10010110

The four numbers in an IP address are called octets, because they each have eight positions when viewed in binary form. If you add all the positions together, you get 32, which is why IPv4 addresses are considered 32-bit numbers. Since each of the eight positions can have two different states (1 or 0) the total number of possible combinations per octet is 2^8 or 256. So each octet can contain any value between 0 and 255. Combine the four octets and you get 2^32 or a possible 4,294,967,296 unique values.

Out of the almost 4.3 billion possible combinations, certain values are restricted from use as typical IP addresses. For example, the IP address 0.0.0.0 is reserved for the default network and the address 255.255.255.255 is used for broadcasts.

Ok, comming back to the example, imagine if people had to remember the IP address of 74.53.251.150 to browse www.vishalvasu.com. Complicated? That’s just one site and imagine if one had to remember sites like hotmail.com, yahoo.com, google.com, microsoft.com, ebay.com, etc. in similar fashion. The thought itself is boring. To make things simpler, the TCP/IP protocol uses a system called DNS (Domain Name System). The basic role of a DNS is to map text names to an IP Address automatically. This way, one only needs to remember www.vishalvasu.com instead of 74.53.251.150. Even though it is totally invisible, DNS servers handle billions of requests every day and they are essential to the Internet’s smooth functioning.

What Next?

IPv4 offers approximately 4.3 billion possible combinations of IP addresses which can used on the TCP/IP network. This is a limit which is feared to get exhausted by 2012 or probably even before that. This fear also led to lot of discussions, research and debates among Internet Engineering Task Force (IETF) since 1980’s. Finally, sometime in 1998, the announcement of IP Version 6 (IPv6) was made. IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network autoconfiguration.

IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period. Basically, the address size was increased from 32 bit to 128 bit, which is deemed sufficient for the foreseeable future.