Re: Address Family Support in OSPFv3

[Sina Mirtorabi <[e-mail]>]

Acee, all


Let me summarize what are the disadvantages of using Instance-ID to run
multiple AF


running multiple instance will

a) require to maintain more adjacencies, in fact to add N AF you may
have to add N adjacencies. This will increase sending and processing of
Hello packet by N for each node

b) require to maintain more LSDB, in fact type 1 & 2 LSA ( which are Not
AF specific) are used again in each instance for each overlapping AF
topology

c) increase the flooding and processing of OSPF packets, this result
from an increase in adjacency and regeneration of type 1&2 LSA within
each instance

D) need a mapping of instance-ID to AF which is user dependent and can
be prone to misconfiguration and increase troubleshooting.

Further other routing protocols ( ISIS, BGP, EIGRP) have adopted AF,
although OSPFv2 -> OSPFv3 transition went with SIN ( ship in the night)
because of inability of v2 to add AF, OSPFv3 separated topology
information and AF specific information and move toward AF integration.
I am not sure we want to fall back to SIN by using instance_ID

Thanks
Sina