Unable to ping VM when using nova.virt.libvirt.vif.LibvirtHybridOVSBridgeDriver

[Gary Kotton]

I did the following steps:
1. Deployed devstack with the following quantum services: q-svc,quantum,q-agt,q-dhcp,q-l3
2. Booted 2 VM's
    nova boot --image cirros-0.3.0-x86_64-uec --flavor 1 t1
    nova boot --image cirros-0.3.0-x86_64-uec --flavor 1 t2
3. Via the DHCP netns did the following:
    sudo ip netns exec <dhcpnetns> ping 10.0.0.1 => succeeds to gateway
    sudo ip netns exec <dhcpnetns> ping 10.0.0.2 => succeeds to dhcp
    sudo ip netns exec <dhcpnetns> ping 10.0.0.3 => succeeds to VM t1
    sudo ip netns exec <dhcpnetns> ping 10.0.0.4 => fails to VM t2

If I use the driver nova.virt.libvirt.vif.LibvirtOpenVswitchDriver then the above works.
Thanks
Gary

[Salvatore Orlando (salvatore-orlando)]

I will try to reproduce and fix. It seems there's a good chance that the root cause for this is the same as bug 1053312

[Gary Kotton (garyk)]

The ovs-vsctl output

    Bridge br-int
        Port "tapc9364e24-13"
            tag: 1
            Interface "tapc9364e24-13"
                type: internal
        Port "qr-1e222570-99"
            tag: 1
            Interface "qr-1e222570-99"
                type: internal
        Port "qvo905afea2-5c"
            tag: 1
            Interface "qvo905afea2-5c"
        Port br-int
            Interface br-int
                type: internal
        Port "qvo709af0ad-06"
            tag: 1
            Interface "qvo709af0ad-06"

Please note that one is defined as internal, the other not. This could be the problem.

[Gary Kotton (garyk)]

Sorry my bad - got mixed up with the qvo and the qr. Ooof

[Gary Kotton (garyk)]

Hi,
Please see below

openstack@openstack:~/devstack$ brctl show
bridge name bridge id STP enabled interfaces
br-eth0 0000.02d2adc0cf4d no
br-ex 0000.b2b906449044 no qg-4a335bfd-1b
br-int 0000.7257fec5e24f no qr-c8ef03f0-4b
       qvo5ba78f1c-24
       qvo74367ad4-b1
       tap28c691c2-7d
br-tun 0000.46a41b9dfb4b no
lxcbr0 8000.000000000000 no
qbr5ba78f1c-24 8000.6eb952e65031 no qvb5ba78f1c-24
       vnet1
qbr74367ad4-b1 8000.de7f077c09c6 no qvb74367ad4-b1
       vnet0
qbrfba045eb-35 8000.7a4e10bc76e8 no qvbfba045eb-35
       vnet2
virbr0 8000.000000000000 yes
openstack@openstack:~/devstack$

The VM that is attached to qvbfba045eb-35 does not respond. The reason is that the qvofba045eb-35 is not part of the br-int. Not sure where this is added and why it fails. Hope that this helps.
Thanks
Gary

[Akihiro Motoki (amotoki)]

Hi Gary,

This is the same bug as bug 1053312 as Salvatore commented.
I found a workaround for this (please see bug 1053312 for detail).
But it is a good chance to address the root issue that plug() is called twice during launching an instance.