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We are currently migrating from vmware server to kvm. So far everything works smooth, with the exception of the secondary bridge.

Our network layout is as follows:

Firewall with 3 ports

eth0 Public Internet IP address
eth1 Internal network 192.168.200.x
eth2 DMZ internal network 192.168.202.x

On the KVM host we also have two NIC's, one attached to the eth1 port of the firewall and the secondary to the eth2 port of the firewall.

We defined two bridges in the KVM host, so we have a bridge for the internal servers (192.168.200.x) and one for the DMZ servers (192.168.202.x)

The network config of the KVM host looks like this:

auto lo br0 br1 eth0 eth1
iface lo inet loopback

iface eth0 inet manual
iface br0 inet static
        bridge_ports eth0

iface eth1 inet manual
iface br1 inet static
        bridge_ports eth1

KVM guest which are located in the 192.168.200.x network (bound to br0) can communicate just fine. But KVM guests with IP's 192.168.202.x (bound to br1) have connectivity only at random. Sometimes the guest have connectivity for 20 seconds, then for several minutes/hours no connection.

Any ideas?

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It finally turned out that the config was perfectly correct, but the network card had a problem.

After replacing the second network card (eth1) with a model from another brand it now works as intended

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