Comment 18 for bug 1522980

Reviewed: https://review.openstack.org/255237
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=26d8702b9d7cc5a4293b97bc435fa85983be9f01
Submitter: Jenkins
Branch: master

commit 26d8702b9d7cc5a4293b97bc435fa85983be9f01
Author: venkata anil <email address hidden>
Date: Thu Aug 4 07:14:47 2016 +0000

    l2pop fdb flows for HA router ports

    This patch makes L3 HA failover not depended on neutron components
    (during failover).

    All HA agents(active and backup) call update_device_up/down after wiring
    the ports. But l2pop driver is called for only active agent as port
    binding in DB reflects active agent. Then l2pop creates unicast and
    multicast flows for active agent.
    On failover, flows to new active agent is created. For this to happen -
    all of database, messaging server, neutron-server and destination L3
    agent should be active during failover. This creates two issues -
    1) When any of the above resources(i.e neutron-server, .. ) are dead,
       flows between new master and other agents won't be created and
       L3 Ha failover is not working. In same scenario, L3 Ha failover will
       work if l2pop is disabled.
    2) Packet loss during failover is higher as above neutron resources
       interact multiple times, so will take time to create l2 flows.

    In this change, we allow plugin to notify l2pop when update_device_up/down
    is called by backup agents also. Then l2pop will create flood flows to
    all HA agents(both active and slave). L2pop won't create unicast flow for
    this port, instead unicast flow is created by learning action of table 10
    when keepalived sends GARP after assigning ip address to master router's
    qr-xx port. As flood flows are already created and unicast flow is
    dynamically added, L3 HA failover is not depended on l2pop.

    This solves two isses
    1) with L3 HA + l2pop, failover will work even if any of above agents
       or processes dead.
    2) Reduce failover time as we are not depending on neutron to create
       flows during failover.
    We use L3HARouterAgentPortBinding table for getting all HA agents of a
    router port. HA router port on slave agent is also considered for l2pop
    distributed_active_network_ports and agent_network_active_port_count

    Closes-bug: #1522980
    Closes-bug: #1602614
    Change-Id: Ie1f5289390b3ff3f7f3ed7ffc8f6a8258ee8662e