OVS bridge not passing traffic

asked 2013-10-24 13:18:08 -0600

larsks gravatar image

updated 2013-10-24 13:39:13 -0600

I have a two-node Grizzly deployment using Quantum + GRE tunnels. After rebooting the network controller, instances on the compute node are no longer able to reach the default gateway.

The network is defined in quantum:

# quantum net-list
| id                                   | name   | subnets                                              |
| 42888e36-6201-4a61-b3e9-57780d5f0be2 | public | bc281373-a3ab-4451-9027-524fe14dcb5b |
| d8c7e39a-47bd-46da-aff7-255f6bac55cb | net0   | e2dddf26-2407-4c38-b69a-71564aea67d8     |

As is the router:

# quantum router-list
| id                                   | name      | external_gateway_info                                  |
| a3d7ec8e-3c4a-45f3-bade-25f0e69138cd | pubrouter | {"network_id": "42888e36-6201-4a61-b3e9-57780d5f0be2"} |

And the appropriate network namespace exists:

# ip netns

The output of ovs-vsctl show looks like this:

    Bridge br-tun
        Port "gre-2"
            Interface "gre-2"
                type: gre
                options: {in_key=flow, out_key=flow, remote_ip=""}
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
    Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port "tap1febee5a-7e"
            Interface "tap1febee5a-7e"
    Bridge br-int
        Port br-int
            Interface br-int
                type: internal
        Port "tap5accf990-b0"
            tag: 1
            Interface "tap5accf990-b0"
        Port "tapf246dd31-e0"
            tag: 1
            Interface "tapf246dd31-e0"
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
    ovs_version: "1.11.0"

With an instance at on the compute node running ping, I can see ARP packets coming across the GRE tunnel:

# tcpdump -i eth1 -n
13:34:25.724597 IP > GREv0, key=0x2, length 54: ARP,
  Request who-has tell, length 28

And I can see them showing up on tapf246dd31-e0 (which is on br-int):

# tcpdump -i tapf246dd31-e0 -n
13:35:30.813915 ARP, Request who-has tell, length 28

But I do not see them on tap5accf990-b0, which is what connects to the router namespace. I'm not sure what to do to further debug this problem. The packets are obviously getting as far as tapf246dd31-e0, and tap5accf990-b0 is on the same bridge with the same tag but is apparently not seeing the packets.

What else should I look at?

UPDATE: I should emphasize that this was working prior to rebooting the network controller. Also, instances are perfectly capable of reaching the DHCP server at (inside qdhcp-d8c7e39a-47bd-46da-aff7-255f6bac55cb).

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What os and version is this? Ovs shows 2 interfaces with prefix tap - I guess you must be using veths to connect them to their namespaces. Try tcpdump on the interfaces inside the namespaces: do 'sudo ip netns exec qrouter-a3d7ec8e-3c4a-45f3-bade-25f0e69138cd ip address'

darragh-oreilly gravatar imagedarragh-oreilly ( 2013-10-24 13:35:31 -0600 )edit

This is on RHEL 6.4 (using the RHOS 3.0 distribution, which includes the necessary network namespace support). `tcpdump` on the network interface inside the router namespace does not show any traffic.

larsks gravatar imagelarsks ( 2013-10-24 13:38:07 -0600 )edit

I don't know. I'd check the l3-agent and ovs-agent logs for errors. And syslog after that.

darragh-oreilly gravatar imagedarragh-oreilly ( 2013-10-24 14:12:57 -0600 )edit

1 answer

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answered 2013-10-24 15:05:17 -0600

larsks gravatar image

This isn't really an answer, but it solved the problem:


ovs-vsctl del-port br-int tap5accf990-b0

...followed by...

ovs-vsctl add-port br-int tap5accf990-b0 tag=1

Got things working again. If someone out there can identify the root cause for this behavior that would be awesome.

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Have you got quantum-ovs-cleanup set to run at boot time?

darragh-oreilly gravatar imagedarragh-oreilly ( 2013-10-24 15:12:27 -0600 )edit

Just checked, and yes.

larsks gravatar imagelarsks ( 2013-10-24 15:18:21 -0600 )edit

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Asked: 2013-10-24 13:18:08 -0600

Seen: 5,564 times

Last updated: Oct 24 '13