IPv6: IS-IS or OSPFv3

Randy Bush randy at psg.com
Sat Dec 27 18:52:03 UTC 2008

>> 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?
> Personally, if my v4 and v6 topologies are not different, I'd run ISIS
> and not run MT. MT for me is to make v4 and v6 have different control
> planes (even though it's using the same protocol), thus I see little
> difference in running OSPFv3+ISIS, or running ISIS-MT for v4+v6.
> I argue that it's better to have different control planes for v4 and v6
> and make it obvious (OSPv3 / ISIS), than to use ISIS-MT and "obfuscate".

the real control plane is bgp.  is-is is for recursive resolution to 
find bgp's next hop interface, fertig.  so the simpler the better.  i am 
annoyed enough that bgp4 and bgp6 peerings and configs are overly 
divergent.  running a different igp for 6 and 4 would not make me happy.


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