Comment 28 for bug 1461882

Reviewed: https://review.opencontrail.org/24761
Committed: http://github.org/Juniper/contrail-vrouter/commit/e9d6b26794da49e3bcb617a785520d45b67b03fa
Submitter: Zuul
Branch: master

commit e9d6b26794da49e3bcb617a785520d45b67b03fa
Author: Divakar D <email address hidden>
Date: Sat Oct 8 19:25:38 2016 +0530

Transmit V6 Neighbour advertisement on the receiving interface

This fix is IPV6 equivalent of
https://review.opencontrail.org/#/c/11506/.

In in-network service instance case, when service scaling
is more than one, all the instances are going to have the
same mac address and IP address. Inet route points to
ECMP composite nexthop but FDB route does not point to ECMP
nexthop. So when neighbour request is received from service VM
Vrouter needs to send response on the incoming interface
rather bridging the reply packet, as FDB route points
to arbitrarly any of the service VM encap L2 nexthop.

After preparing the reply packet,bridge lookup is done
and outgoing interface is compared against ingress interface.
If they are not same, reply packet is transmitted on
ingress interface.

Change-Id: Ib0113227019d7a452541129843813a647d388b36
closes-bug: #1461882