On Thu, Oct 13, 2011 at 12:28 AM, Eric Searcy <emsearcy at gmail.com> wrote: > 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 > _______________________________________________ > CentOS-virt mailing list > CentOS-virt at centos.org > http://lists.centos.org/mailman/listinfo/centos-virt > Sorry for the delayed reply. As you guys said, I checked the hardware, even replaced something. I think it is sure that the hardware is OK. The system is CentOS 5.5, and for some reason I cannot update it. The problem always and only could be resolved by rebooting. -- 竹密岂妨流水过 山高哪阻野云飞