On Saturday 27 December 2008 09:27:05 pm Randy Bush wrote:
as one who has been burned when topologies are not congruent, i gotta ask. if i do not anticipate v4 and v6 having different topologies, and all my devices are dual-capable, would you still recommend mt for other than future-proofing?
In practice, we realized that enabling IS-ISv6 on interfaces already running IS-ISv4 was problematic without MT pre- configured. Those links surely lost IS-IS adjacency which threatened stability of the network. Things could probably have been easier if all routers accepted all transition commands at the same time (or if all routers were pre-configured and powered on at the same time), but that's not possible. MT allowed us to bring up individual v6 links on the same and different routers, at different times, without bringing down the v4 network, considering that several routers had as many as 4 - 6 links into the core. Cheers, Mark.