Comment 5 for bug 1524020

Reviewed: https://review.openstack.org/270456
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=80c9e84e477bbc6db9195fcf3e537f96e684946b
Submitter: Jenkins
Branch: stable/liberty

commit 80c9e84e477bbc6db9195fcf3e537f96e684946b
Author: Swaminathan Vasudevan <email address hidden>
Date: Fri Dec 4 11:58:57 2015 -0800

    DVR:Fix _notify_l3_agent_new_port for proper arp update

    Now with notifications coming from ml2 plugin on port create
    and port update, it is worth fixing the existing _notify_
    l3_agent_new_port for proper arp update and router scheduling.

    Previously we have been sending arp update and calling router
    scheduling for every update notification for service ports,
    but now we can take necessary action only when required, since
    the fix to update the arp and router scheduling was recently
    done by sending the port info for every new port created.

    When _notify_l3_agent_port_update is triggered, we check if the
    original port host binding exists and if there is a change in
    host binding with respect to the new port, then we go ahead and
    reschedule the router on the new host and flush the arp entry.

    Related-Bug: #1524020

    Change-Id: Ifda623d5413b72bf80f38fba5c12a05a88bb7de5
    (cherry picked from commit b223452e68fa8629cb67826bb8ae3ac612e0b859)