[j-nsp] IS-IS MT transition mode?

[Michael Sinatra]

On 06/25/12 19:47, Jared Gull wrote:
> Hi Michael,
>
> You can enable an IPv6 unicast topology in addition to the default IPv4
> and IPv6 topology for IS-IS using the 'topologies' keyword:
>
> [edit]
> user at router# set protocols isis topologies ?
> Possible completions:
> + apply-groups Groups from which to inherit configuration data
> + apply-groups-except Don't inherit configuration data from these groups
> ipv4-multicast Enable IPv4-multicast topology
> ipv6-multicast Enable IPv6-multicast topology
> ipv6-unicast Enable IPv6-unicast topology

That's the JunOS equivalent of 'multi-topology'.  It is NOT the 
equivalent of 'multi-topology transition'.  In IOS, 'multi-topology 
transition' allows the router to send both single- and multi-topology 
TLVs with IPv6 routes.  In JunOS, when you enable topologies (i.e. IS-IS 
multi-topology) where you previously had IPv4 and IPv6 routes in the 
single-topology, other routers must also be *immediately* switched to 
multi-topology or you will have holes in your IPv6 routing table. 
That's because the IPv6 routes are announced in the MT #2 TLV and NOT in 
the MT #0 (single-topology equivalent) TLV.

My goal is to gradually switch from single-topology to multi-topology in 
a production IPv6 network, without routing holes.  I believe this can be 
done in Brand C, although I am in the process of testing it.  Can it be 
done in Brand J?

thanks,
michael