[CentOS] KVM Bridge Problem

Hello,
is this only my mistake,or can help any from the list?

I have 3 host computer on different places, but all have the Problem when 
starting a client "KVM" to connect to the bridge from the host.

It is near not possible to start a client, only after 10-20 reboot/restart 
from the client's the network is starting correct?

Is this  only on my computers or have other also this Problem?

Is the bridge software is broken ?

Can I use openvswitch to replace bridge Software?

Any help are welcome ;-)
 
-- 
mit freundliche Grüßen / best regards,

  Günther J. Niederwimmer