Comment 12 for bug 1542108

Reviewed: https://review.openstack.org/305782
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=c55aba1dba31c6730c80db0118286f1f9e84cd9b
Submitter: Jenkins
Branch: stable/liberty

commit c55aba1dba31c6730c80db0118286f1f9e84cd9b
Author: Kevin Benton <email address hidden>
Date: Mon Feb 22 16:41:45 2016 -0800

    Make agent interface plugging utilize network MTU

    This changes the 'plug' and 'plug_new' interfaces of the
    LinuxInterfaceDriver to accept an MTU argument. It then
    updates the dhcp agent and l3 agent to pass the MTU that
    is set on the network that the port belongs to. This allows
    it to take into account the overhead calculations that are
    done for encapsulation types.

    It's necessary for the L3 agent to have the MTU because it
    must recognize when fragmentation is needed so it can fragment
    or generate an ICMP error.

    It's necessary for the DHCP agent to have the MTU so it doesn't
    interfere when it plugs into a bridge with a larger than 1500
    MTU (the bridge would reduce its MTU to match the agent).

    If an operator sets 'network_device_mtu', the value of that
    will be used instead to preserve previous behavior.

    Conflicts:
     neutron/agent/l3/dvr_edge_ha_router.py
     neutron/agent/l3/dvr_edge_router.py
     neutron/agent/l3/ha_router.py
     neutron/agent/linux/interface.py
     neutron/tests/functional/agent/l3/test_dvr_router.py
     neutron/tests/functional/agent/test_dhcp_agent.py

    Additional modifications for Liberty:
    - test_dvr_router_lifecycle_ha_with_snat_with_fips_nmtu renamed into
      test_dvr_router_lifecycle_without_ha_with_snat_with_fips_nmtu,
    - the test validates DVR without HA.

    Reason for the change: Liberty does not support DVR + HA routers (the
    test raises DvrHaRouterNotSupported without those modifications).

    Closes-Bug: #1549470
    Closes-Bug: #1542108
    Closes-Bug: #1542475
    DocImpact: Neutron agents now support arbitrary MTU
               configurations on each network (including
               jumbo frames). This is accomplished by checking
               the MTU value defined for each network on which
               it is wiring VIFs.
    Co-Authored-By: Matt Kassawara <email address hidden>
    (cherry picked from commit 4df8d9a7016ab20fce235833d792b89309ec98a7)

    ===

    Also squashing in the following fix to pass unit tests for midonet
    interface driver:

    Support interface drivers that don't support mtu parameter for plug_new

    The method signature before Mitaka did not have the mtu= parameter. We
    should continue supporting the old signature, since it can be used in
    out of tree interface drivers. The class is part of public neutron API,
    so we should make an effort to not break out of tree code.

    Local modifications:
    - don't issue a deprecation warning in minor release update.

    Change-Id: I8e0c07c76fd0b4c55b66c20ebe29cdb7c07d6f27
    Closes-Bug: #1570392
    (cherry picked from commit 8a86ba1d014a5e758c0569aaf16cfe92492cc7f1)

    ===

    Change-Id: Ic091fa78dfd133179c71cbc847bf955a06cb248a