error in openstack:

# lsmod|grep brcomp
brcompat               13512  0 
openvswitch            84038  8 brcompat

# service openvswitch-switch status
ovsdb-server is running with pid 2186
ovs-vswitchd is running with pid 2228
ovs-brcompatd is running with pid 3007


2013-02-17 10:26:14 DEBUG nova.utils [req-1591a4d4-9779-452f-bd87-2801f25ae592 None None] Running cmd (subprocess): sudo nova-rootwrap /etc/nova/rootwrap.conf brctl addif qbreb2557ea-3b qvbeb2557ea-3b execute /usr/lib/python2.7/dist-packages/nova/utils.py:183
2013-02-17 10:26:14 DEBUG nova.utils [req-1591a4d4-9779-452f-bd87-2801f25ae592 None None] Result was 1 execute /usr/lib/python2.7/dist-packages/nova/utils.py:199
2013-02-17 10:26:14 2046 CRITICAL nova [-] Unexpected error while running command.
Command: sudo nova-rootwrap /etc/nova/rootwrap.conf brctl addif qbreb2557ea-3b qvbeb2557ea-3b
Exit code: 1
Stdout: ''
Stderr: "can't add qvbeb2557ea-3b to bridge qbreb2557ea-3b: Invalid argument\n"
2013-02-17 10:26:14 2046 TRACE nova Traceback (most recent call last):
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/bin/nova-compute", line 48, in <module>
2013-02-17 10:26:14 2046 TRACE nova     service.wait()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 659, in wait
2013-02-17 10:26:14 2046 TRACE nova     _launcher.wait()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 192, in wait
2013-02-17 10:26:14 2046 TRACE nova     super(ServiceLauncher, self).wait()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 162, in wait
2013-02-17 10:26:14 2046 TRACE nova     service.wait()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 166, in wait
2013-02-17 10:26:14 2046 TRACE nova     return self._exit_event.wait()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/eventlet/event.py", line 116, in wait
2013-02-17 10:26:14 2046 TRACE nova     return hubs.get_hub().switch()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 177, in switch
2013-02-17 10:26:14 2046 TRACE nova     return self.greenlet.switch()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 192, in main
2013-02-17 10:26:14 2046 TRACE nova     result = function(*args, **kwargs)
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 132, in run_server
2013-02-17 10:26:14 2046 TRACE nova     server.start()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 398, in start
2013-02-17 10:26:14 2046 TRACE nova     self.manager.init_host()
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 297, in init_host
2013-02-17 10:26:14 2046 TRACE nova     self.driver.plug_vifs(instance, legacy_net_info)
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 439, in plug_vifs
2013-02-17 10:26:14 2046 TRACE nova     self.vif_driver.plug(instance, (network, mapping))
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/vif.py", line 221, in plug
2013-02-17 10:26:14 2046 TRACE nova     utils.execute('brctl', 'addif', br_name, v1_name, run_as_root=True)
2013-02-17 10:26:14 2046 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 206, in execute
2013-02-17 10:26:14 2046 TRACE nova     cmd=' '.join(cmd))
2013-02-17 10:26:14 2046 TRACE nova ProcessExecutionError: Unexpected error while running command.
2013-02-17 10:26:14 2046 TRACE nova Command: sudo nova-rootwrap /etc/nova/rootwrap.conf brctl addif qbreb2557ea-3b qvbeb2557ea-3b
2013-02-17 10:26:14 2046 TRACE nova Exit code: 1
2013-02-17 10:26:14 2046 TRACE nova Stdout: ''
2013-02-17 10:26:14 2046 TRACE nova Stderr: "can't add qvbeb2557ea-3b to bridge qbreb2557ea-3b: Invalid argument\n"
2013-02-17 10:26:14 2046 TRACE nova