The European Union recently urged telecoms carriers and service providers to adopt the IPv6 addressing scheme as quickly as possible to gain a competitive edge. But many firms are reluctant to build support for IPv6 technology into their infrastructure, and with good reason, according to some experts.

Although IPv6 has a number of advantages for network management, performance and security, its prime benefit lies in the ability to support up to 3.4x10³⁸ IP addresses simultaneously, a huge increase on the four billion currently supported by IPv4. Companies linking large numbers of users to the Internet have so far overcome the limitation by using dynamic rather than static IP addressing schemes and Network Address Translation (NAT), which maps multiple private IP addresses to a single public one.

According to Uri Rahamim, vice president of IPv6 router manufacturer Hitachi Internetworking, firms need to start upgrading their infrastructure to support IPv6 now, or risk being left behind by their competitors in terms of the applications and services they will be able to offer to customers. "The incredible growth of the Internet over the past few years has brought the limitations of IPv4 to the surface," said Rahamim, who believes the increasing number of mobile devices attached to the Web will drive the need for IPv6.

"IPv6 also provides end-to-end security and QoS [quality of service] that cannot be provided by IPv4. And it offers addressing mechanisms, such as fixed IP addresses for roaming different mobile networks, that NAT does not offer," he added.

Paul Francis, chief scientist at Tahoe Networks and one of the creators of IPv6, argued that European carriers should be cautious about implementing the protocol, and should run applications and services over IPv4 where possible. "Everybody agrees that a pure IPv6 world would be simpler, cheaper and more efficient than a pure IPv4/NAT world. But nobody can quantify that, nor does anyone clearly understand the costs associated with getting to that world," he said.

Francis stressed that service providers should fully understand how every service they want to offer works with both IPv4 and IPv6. "If any given service can be profitably offered with IPv4, then they should only move to IPv6 if relatively near-term cost savings in using IPv6 can be clearly demonstrated," he said.

Francis added that there was not a single Internet application that runs over IPv6 and not IPv4, and pointed out that although peer-to-peer is easier and simpler over IPv6, it can work with IPv4 users behind NAT devices. "The use of NAT extends the IPv4 address space almost indefinitely," Francis said.

Francis warned that the transition to a pure IPv6 will be long and costly. "The longer the transition is, the more early adopters of IPv6 may be hurt," he said.

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