In this section, we look at Cisco's and Juniper's support for IPv6. They are not the only vendors in the IPv6 market, but they are two vendors that many people will be familiar with.
Cisco detail support for IPv6 across their various routers on their web site at http://www.cisco.com/ipv6/. However, IPv6 performance varies from platform to platform.
For software-based routers, such as the 2500, 2600 and 7200, it is possible to achieve respectable IPv6 performance at the current time with just an IOS upgrade. Maximum speeds are not yet on a par with IPv4, and many of the more complex features haven't been implemented for IPv6 yet, but this should improve as releases continue.
Cisco IOS support for IPv6 first appeared on the public radar with the 12.2T stream. As a "new technology" release, some readers may be familiar with the T streams if they are using other new features. Like all new technology releases, it has a rather large memory footprint, and may contain other new features that one may not wish to deploy in production yet.
The 12.3 stream is the first mainline IOS stream with support for IPv6. Cisco provides TAC support for the IPv6 features of 12.3. This is also a fairly hefty piece of code, and older equipment might require memory upgrades in order to support it.
An alternative is the 12.2S stream which appeared in 2004. It is aimed at service providers who wish to use IPv6 in a smaller package more tuned to their needs, or who are reluctant to make the leap to ...