Hi, We are using Centos 5.5. as KVM host. It has two nics. One for management and the other one for services. As we have services in multiple vlans this nic is configured as a 802.1Q trunk. Any VM must be able to have access to any vlan, so host trunk interface is bridged to its tap interface and vlan is configured inside VM. Everything works fine while there is not heavy traffic. I can not find any log on guest or host, but, after some certain sustained big file transfer (about 6Gb) bridging stop working. Other guest on the same host continue working without problems. tcpdump on bridge interface is Ok, but on guest tap inferface I can see only outgoing traffic. Restarting bridge or rejoining tap interface doesn't provide any clue. Rebooting guest turns on bridge again. Bridge configuration is minimal: just addbr and addif (no stp). Any idea welcome!