On Wed, Dec 28, 2011 at 04:58:19AM +0530, Glen Kent wrote:
It seems ISIS and OSPFv3 use the link local next-hop in their route advertisements.
We discussed that SLAAC doesnt work with prefixes > 64 on the ethernet medium (which i believe is quite, if not most, prevalent). If thats the case then how are operators who assign netmasks > 64 use ISIS and OSPF, since these protocols will use the link local address?
I had assumed that nodes derive their link local address from the Route Advertisements. They derive their least significant 64 bytes from their MACs and the most significant 64 from the prefix announced in the RAs.
Each prefix on an interface can have a different prefix length. Link-locals always have a prefix length of 64, even if a global address assigned to the same interface has a different length. Also, the link-local address is derived locally without any information from RAs.