On 10/Jun/15 21:56, Robert Drake wrote:
When we first were moving to IPv6 in the core network we evaluated IS-IS because it was what we were using for IPv4 and we would have preferred to run a single protocol for both. We had problems with running a mix of routers where some supported IPv6 and others did not. From what I recall, if any router did not support IPv6 then it wouldn't connect to a router running v6 and v4.
It's possible these were bugs and they were worked out later or just a messed up design in the lab, but we also like the idea of keeping IPv4 and IPv6 away from each other so if one is broken the other one might still work.
Someone may have already mentioned this, but you hit that issue because you were probably running ST (Single Topology) IS-IS. IS-IS supports MT (Multi Topology) which allows you to have incongruent IP stacks on a link, i.e., IPv4 on one end + IPv4/IPv6 on another. As the majority of strategies to implement IPv6 will be in this manner, always recommended to run IS-IS in MT mode. Unless you were implementing IS-IS before MT was supported in code. Mark.