IPv6 adoption vs IPv4

IPv6 is supposed to be the next upgrade to the current IPv4 protocol, which dominates the Internet.

Wednesday, February 22, 2006

Print

Comment

Email

Digg

Del.icio.us

Reddit

Twitter

So far IPv6 has managed to grab only a small part of the Internet pie, but there's plenty of action happening in the background to make the existing Internet infrastructure ready for it. Will the Internet ever shift to the new protocol anytime soon? Let's take a look.

The original intention for designing IPv6 was that the available IP address range in IPv4 was running out quickly. There were just not enough IP addresses in IPv4 to give to everybody. In fact, even the distribution of IPv4 addresses globally was skewed, with a major portion of them allotted to the US and Europe and a small part to Asia Pacific countries. With Internet connectivity growing rapidly in these countries, this skew will have its effect. Even otherwise, the distribution is inefficient with many companies sitting with lots of unused blocks of IP addresses. IPv4 countered both these problems for more IP addresses by devising Network Address Translation or NAT technology. This needs no introduction, as most organizations already use it to allow machines on their network to share an IP address and access the Internet. But NATing has only slowed down the adoption of IPv6 for some time. It's not going to stop it completely.

The thirst for more IP addresses is much bigger and increasing. Consider the mobile revolution that's currently happening globally.  So many digital devices like cellphones, PDAs, smartphones, etc have become available today. Most of these can connect to the Internet, and therefore need an IP address. There's no way that IPv4 would be able to handle this onslaught of new devices. NATing would only work to some extent.

More IP addresses isn't the only reason to shift to IPv6, though that was the original intention. Besides this reason, even the older IPv4 has some other limitations that IPv6 promises to overcome. These can be best understood by looking at the benefits of IPv6. One is that the new protocol is supposed to have better routing techniques. Unlike IPv4 implementations, in which the routers maintain huge routing tables, IPv6 would be able to manage with smaller tables. That's because a lot of information about the source and destination is built into the IPv6 header itself. This will allow IPv6 packets to reach their destinations in fewer hops.  Another limitation that IPv6 overcomes is getting an IP address from a DHCP server. In IPv4, if a machine is configured to obtain an IP from a DHCP server, it won't be able to get an IP address if the DHCP server isn't available. IPv6 on the other hand, is supposed to be smart enough to figure out an IP address from a routing table or from IP addresses of nearby clients. Likewise, IPv6 is supposed to have better support for security, with integrated IPSec support. Even if we look at the addressing scheme, we'll find many benefits. Since there's such a huge number of IP addresses available, a company won't really need to do NATing. Likewise, there can be more levels of subnetting also possible.

Given all these benefits, there's some movement towards implementing the protocol. The US federal agencies are supposed to shift to IPv6 by 2008. China, Korea and Japan have also been considering the shift to IPv6. In fact, in July 2004, IPv6 records were visible for Japan and Korea's TLD (top level domain) name servers became visible in the DNS root servers. The IPv6 records for France have also been added. Besides these, several key conferences were hosted last year to create awareness about the protocol. Work is on at the software front as well. Windows XP already has a trial deployment for it, while some versions of Linux also support it. There's a company that's deploying a DHCP server test suite for IPv6. The IPv6 forum has task forces from around 35 countries working on the protocol.

Despite all this action, IPv6 adoption is still a little slow. Part of the reason is that it's not backward compatible with IPv4. An IPv4 router won't support IPv6. It must have inherent support build in for both protocols. Likewise, all applications and Operating Systems must add the support for the new protocol. Just because this happens, it doesn't meant that all companies and ISPs will immediately shift to the new protocol. It will take time, as everybody would first have to understand the complexities and challenges involved, do some pilot runs before doing the transition. Its migration will be like any other technology. There will first be an intermediate stage where, where both IPv4 and IPv6 will coexist. This will then slowly transition to the new protocol. But the complete transition is not likely to happen any time soon. Should you be worried about IPv6 now? Well, as there's plenty of time for the transition to happen, you might like to consider doing some dry runs of the same. It shouldn't happen that the world migrates to the new protocol and enjoys its benefits, while you're left behind.

Anil Chopra, Associate Editor

Page(s)   1