[Openstack] Intermittent connectivity problems from qrouter namespace

Mina Nagy Zaki mnzaki at gmail.com
Mon Aug 26 21:27:01 UTC 2013

That's a great guess :D I did manage to figure this out earlier and it
took me a day of understanding OVS and following datapath/flow dumps
until I realized that the non-standard configuration I had was causing
the creation of a GRE tunnel from the machine to itself (on another


On Mon, Aug 26, 2013 at 5:24 PM, Darragh O'Reilly
<dara2002-openstack at yahoo.com> wrote:
> badly configured tunnels can cause the symptoms you see. So you
> could focus on that if your quantum network is using gre tunnels.
> Run 'ovs-vsctl show' on each node and check the remote_ip of each
> port on br-tun.
>> From: Mina Nagy Zaki <mnzaki at gmail.com>
>>To: openstack <openstack at lists.openstack.org>
>>Sent: Saturday, 24 August 2013, 11:38
>>Subject: [Openstack] Intermittent connectivity problems from qrouter    namespace
>>I'm using nova 2013.1.2 with quantum/neutron.
>>I have a router with a fixed net and an external gateway. There's
>>unexplained packet loss from the router's network namespace to the
>>VM's fixed IPs. I've seen it with ARP requests, ping requests, and
>>pretty much everything else. Sometimes they just don't go through for
>>a while. I've also seen a pattern of 2s, 1s, 0.5s ping times on the
>>first 3 packets, then normal ping times of <1ms.
>>VM -> external network traffic is working great though.
>>I've tried monitoring the OVS flows and they don't seem to change.
>>I've been tcpdumping the interfaces, and packets simply fail to make
>>it over the qbrXXXXX bridge sometimes.
>>Also, after a 'warm up' period of trying to ping the machines and
>>failing, once a few packets make it through it starts working
>>I'm lost. Where do I start with this????
>>Mina Nagy Zaki
>>Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
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Mina Nagy Zaki

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