The Next Version of the Internet Protocol - IPv6

This article answers major questions concerning the new IP protocol- IPv6 and how it will work.

 By Pete Loshin
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By Pete Loshin

IPv6 - The Next Version of the Internet Protocol

A lot of hot air has been blowing over the past year or so about the next version of the Internet Protocol, IPv6. Unlike the Y2K problem or even the move to support the latest version of Microsoft Windows, there are no "flag day" transitions by which time systems must be upgraded or else. Members of the IETF (Internet Engineering Task Force) recognized that the current version of IP, IPv4, would need an upgrade by the late 1980s, and RFCs specifying the new protocol began appearing by 1995. But some big questions remain unanswered: why support IPv6 at all, and how will it work?

Savvy network professionals already know quite a bit about IPv6. For one thing, they know that IPv4 has limited address space and that IPv6 increases the network address size from 32 bits to 128 bits. They know that IPv6 smoothes the rough edges around IPv4 and adds some very nice features such as stateless autoconfiguration ("plug-and-play" networking). But they may not know all that much more about IPv6, especially not about the upgrade paths from IPv4 to IPv6, how to migrate individual hosts and networks, what to do about applications, and where to find more real-world resources for deploying IPv6.

IPv4 is sufficiently robust and scalable to go from serving as the network layer protocol for a research network linking a few dozen government and academic research sites to today's Internet, a global network now linking something on the order of 100 million nodes. But IPv4 was published in RFC 791 back in 1981, and it has needed a face-lift for some time. Number one problem is the IPv4 address space. As anyone who has requested a globally unique IP network address in the past five years knows, they are in very short supply.

Despite the fact that the 32-bit IPv4 address could (in theory at least) uniquely identify over four billion different nodes, much of that space is inaccessible (either reserved or unused). The problem is that addresses were originally apportioned inefficiently. But perhaps an even more pressing problem is how to cope with the explosive growth in Internet routing tables.

This article was originally published on Oct 11, 1999
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