L3 agent restart disrupts fip namespace causing connectivity loss

[Carl Baldwin]

When the L3 agent restarts, it does not preserve the link local addresses used for each router. For this reason, it has to reassign them and rewire everything. This is very disruptive to network connectivity. Connectivity should be preserved as much as possible.

This was an expected backlog item for the new DVR feature.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/109486

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/109486
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=c3c9f580393aea658571b00b3afd0b729dffe89b
Submitter: Jenkins
Branch: master

commit c3c9f580393aea658571b00b3afd0b729dffe89b
Author: Carl Baldwin <email address hidden>
Date: Fri Jul 25 03:57:40 2014 +0000

    Preserve link local IP allocations for DVR fip ns across restart

    The L3 agent allocates link local address pairs used in connecting the
    routers to the floating ip namespace. When those allocations are
    forgetten by restarting the L3 agent they all get rewired on restart.
    This change preserves the allocations using a file in the local file
    system. Storing them in the database would be overkill and would
    affect system performance.

    Change-Id: I39614c7ea2a7dcc35bf969c90045adc5926ea9df
    Closes-Bug: #1348306
    Partially-Implements: blueprint neutron-ovs-dvr
    Co-Authored-By: Rajeev Grover <email address hidden>