[CentOS-virt] Emergency help needed on host network randomly stop working.

Thu Oct 13 09:38:08 UTC 2011
Magicloud Magiclouds <magicloud.magiclouds at gmail.com>

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
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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.