[Openstack] [Quantum] routing does not work as expected after quantum-linux-bridge sets up default route

David Kang dkang at isi.edu
Tue Jul 23 14:32:56 UTC 2013


 We are running OpenStack Folsom on CentOS 6.4.
Quantum-linuxbridge-agent is used.
Its external network is configured to use VLAN 83 and 
its address range is
The IP of the Quantum node is

 The problem is that after reboot, the quantum node cannot
connect to DNS servers ( for a while (sometime tens of minutes).
After boot-up but before the quantum-linuxbridge-agent starts, the default gw is:

default         UG    0      0        0 eth2.183

With the gw, Quantum can get proper data from MySQL server 
and RabbitMQ server using DNS server.

Quantum sets up a bridge on eth2.83 and make it a default gateway (
Now, there are two gateways:

default         UG    0      0        0 qg-49ff6d2f-a7
default         UG    0      0        0 eth2.183

 The physical router is configured to route for DNS servers.
But even with the updated routing table, when I do 'traceroute' DNS server,
it routes through
And it cannot reach DNS server.
When I remove entry from the routing table, it works fine.
But, I think it should work as it is because is lower than in
the routing table.

 What could be wrong?
I will appreciate any help.


Dr. Dong-In "David" Kang
Computer Scientist

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