One thing about next-hop path attribute is not clear to me. In slides 35 and 80 (solutions for 35) edge router changes next-hop attribute to self (188.8.131.52). Is this necessary for the whole scheme to work?
External router's (R5) address (184.108.40.206) is also reachable by all internal routers from AS x as this router has an IP address on a network shared by AS z and AS x. If this is true, no change in next-hop attribute is required.
Also, RFC 1771 (page 22, last paragraph) says:
"When a BGP speaker advertises the route to a BGP speaker located in
its own autonomous system, the advertising speaker shall not modify
the NEXT_HOP attribute associated with the route. When a BGP speaker
receives the route via an internal link, it may forward packets to
the NEXT_HOP address if the address contained in the attribute is on
a common subnet with the local and remote BGP speakers."
Thank you for helping,
Posted by Aleksandar Dragojevic on Tuesday 5 December 2006 at 23:42