On 10/12/11 12:43 AM, Magicloud Magiclouds wrote: > Hi, > This is a Centos 5.5 host with one xen guest. > About 2 weeks ago, the host randomly lost network connection. By > this I mean I could not connect to the services on it, or ping it. > Also was the status of the guest. > From serial console, I connected to the host, trying to see what > happened. No clue (any error messages) in messages or dmesg. > ifdown/ifup the interface did not help, either. Only rebooting was my > only choice. > Searching through Google, I got the information that some other guys > met similar problem, and resolved by setting stp on with the bridge > interface. > I set it, too. And the problem still occurs. > Any idea what I should check now? > Thanks. When outage occurs, from the host these might be good things to look at and/or share with the list: ip link brctl show arp -n (arp -n from your next-hop router too) tcpdump -ln -i peth0 (try some activity; e.g. ping out to router, ping in from router) tcpdump -ln -i br0 (more activity) Depending on your xen bridge setup the bridge might be named eth0 or virbr0; peth0 might be different too. Eric