Week3: Why IP Addresses Are Running Out

The IP address is intrinsic to nearly every event on the Internet, from performing a Google search to playing an online multiplayer match in a videogame. They are the unique identifying addresses of each node upon the Net. However, due to the nature of the IPv4 Protocol the maximum number of IP addresses is 4,294,967,296 (256x256x256x256, or 2³²). This limitation is caused by the fact that the IPv4 address header can be a maximum of 32 bits long.

However, this ceiling is further limited by the assignment of large blocks of IPs to various uses. For example multicast has over 270 million address assigned to it along with another 18 million for private networks. Some allocated addresses are unused and as such take up value space from the public sector assignments.

There are two methods to overcome this. The first involves restricting and controlling the use of existing addresses i.e. allocating only what is necessary and avoiding waste. However most experts feel this is only a short-term solution as at the present rate we will run out of addresses in approximately 3 years.

The second solution is to switch to IPv6, the hopeful successor to v4. IPv6 supports addresses up to 128 bit long raising the ceiling to 3.4x10⁴⁸ addresses, or in more human terms each person on this planet could have a billion, billion, billion addresses of their own with room left over.

The rollout of IPv6 has so far been very slowly with large corporations reluctant to make the jump as it would be very costly. However it may eventually become a requirement as every fridge, phone and arm (Kevin Warwick) gets their own address.