Less than 18% of the total Internet Protocol version 4 (IPv4) address space available was allocated between January 1999 and June 2003, which means there is quite a large block of IPv4 address space remaining.

It is difficult to calculate the growth in demand for new addresses, due to the multiple, complex levels of delegation from the Internet Assigned Numbers Authority (IANA) down through the American Registry for Internet Numbers (ARIN), to Regional Internet Registries (RIR), Local Internet Registries (LIR) and Internet Service Providers (ISP).

The growth of new allocations to LIRs and ISPs dropped between 2001 and 2002, but will likely start to grow again this year, driven largely by allocations in Asia and Europe.

And if allocations in the first half of 2003 are matched in the second half, Asia-Pacific will experience its second consecutive year as the most demanding region, followed by Europe (second year at number two) and then North America.

Given these numbers, it would be considerably longer than a decade before IPv4, which has a total of about 3.5 billion unique addresses, run out. However, predicting demand for addresses is even harder than pinning down how many are in use currently.

This is especially true given the rise of mobile IP devices and the surging demand in Asia for its fair share of IP space

It is said that India, a country of one billion people and a rapidly growing IT industry, has just a handful of Class B address blocks allocated to it. Each Class B has about 65,000 unique addresses.

By comparison, large US companies including Hewlett-Packard [HPQ], Apple [AAPL], Ford [F] and General Electric [GE] were each assigned 16 million addresses in the early 1990s.

Mobile devices will likely also drive demand for more addresses. To have a globally routable IP phone, you need a unique IP address for each device,

The internet was originally designed to be a network of equal peers, but the proliferation of Network Address Translation, NAT, a network gateway technology designed to translate public IP addresses into private addresses, has made that no longer the case.

IPv6 is almost universally believed to be inevitable, but the debate around when IPv4’s address space will run out will likely continue, and will probably be settled only by empirical evidence from the market.

This article was based on material originally published by ComputerWire.