Comment 9 for bug 1592119

Reviewed: https://review.opencontrail.org/21416
Committed: http://github.org/Juniper/contrail-controller/commit/de1f03eb1d2902ba37e4883a99b0d643a80db8ef
Submitter: Zuul
Branch: R3.0

commit de1f03eb1d2902ba37e4883a99b0d643a80db8ef
Author: ashoksingh <email address hidden>
Date: Thu Jun 23 17:20:07 2016 +0530

Add route to trap neighbor advertisement messages to Agent.

Issue:
In case of IPv6 Allowed Address Pair, when switchover happens to new interface,
the traffic does not move to new interface. As part of switchover, Unsolicited
Neighbor Advertisement message from new interface is not trapped to agent.

Fix
Agent now adds a route to trap IPv6 All Nodes Multicast address in each VRF so
that Unsolicited Neighbor Advertisement message reaches agent. Agent, as part
of this message processing updates the Allowed Address pair state machine so
that route preference is updated for new interface and traffic starts flowing
from new interface. Also define separate counters in agent for Solicited and
Unsolicited Neighbor advertisement message.
Also update the UT.

Closes-Bug: #1592119
(cherry picked from commit 6d3008cb1e0fa8bd8316398959785f45e0eef218)

Change-Id: Ic46a99cd096c03d6af23c8fc50cac4bd2c70d0b1