Comment 6 for bug 1048681

Reviewed: https://review.openstack.org/12714
Committed: http://github.com/openstack/quantum/commit/aa5a7aaf47b6cf97a6f35934f68570ecfc16bd4e
Submitter: Jenkins
Branch: master

commit aa5a7aaf47b6cf97a6f35934f68570ecfc16bd4e
Author: Akihiro MOTOKI <email address hidden>
Date: Mon Sep 10 22:21:35 2012 +0900

    Add a new interface driver OVSVethInterfaceDriver.

    Fixes bug 1048681

    This commit fixes a bug that quantum agent using a namespace does not
    work with NEC plugin. NEC plugin uses an Open vSwitch as an OpenFlow switch,
    but an OVS port created by ovs-vsctl add-port becomes down when the port is
    moved to some network namespace. Usual OpenFlow controllers respect the
    OpenFlow port status. Since DHCP server (dnsmasq) is connected to the down
    port, DHCP server disappears from the virtual network.

    This behavior can be avoided if we use a similar approach used in
    BridgeInterfaceDriver, i.e., we first create a veth pair, add one veth device
    to OVS and move the other veth device to a network namespace. To accomplish it
    this patch introduces a new interface driver OVSVethInterfaceDriver.

    In addition, this patch adds a 'prefix' paramter to unplug(). When deleting
    a veth pair, a veth device added to OVS bridge is not removed automatically.
    Thus we need a mean to know the veth device name from a device_name to be
    removed. It is the reason to add 'prefix' parameter to unplug().

    Change-Id: I3f4eae371a27a3171a6a8c9e38ddc9354ed1b6b0