Open Stack

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
>semi-reliably.
>
>I'm lost. Where do I start with this????
>
>-- 
>Mina Nagy Zaki
>
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