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TRENDS IN IP ADDRESSING

IP address space is finite, and as the number of available addresses gets smaller, new addresses and AS numbers will be harder to obtain. As of February 2000, about half of the available IP addresses will be utilized [19]. We anticipate that depletion of addresses will accelerate as the Internet becomes more pervasive worldwide and as more and more devices (cellular phones, game consoles) are becoming able to communicate directly on the Internet.

One technical solution we are evaluating to reduce the number of addresses being used is to use NAT on public web servers. With NAT, a public virtual IP address could be mapped to multiple private addresses, reducing the need for a public IP address per web server. This solution has the potential drawback of complicating monitoring of web servers and debugging of problems since the individual web servers can no longer be individually contacted by the Internet. Also, various security schemes can be broken by using NAT [20].

A longer term solution to the depletion problem is for the Internet to move to IP version 6 [21]. The address space for IPv6 is much much larger, and many of the actions necessitated by IPv4 address scarcity will not be necessary. The address registries have already begun allocating IPv6 address space. Unfortunately, IPv6 is not backward compatible. At the moment, there is not enough economic incentive to undertake large scale conversion to IPv6. We anticipate that this may change as the amount of IPv4 address space is depleted.