Re: [Xen-users] Networking problems on 2.0.7

[Ernst Bachmann <e.bachmann@xxxxxxxx>]

On Wednesday 14 September 2005 00:45, Robert Hulme wrote:
> I'm having some problems on xen 2.0.7
>
> I've setup 5 domains and linked them together such that you have A <->
> B <-> C <-> D <-> E. I have two problems:

Did you use several bridges inside dom0 (one for A+B, one for B+C and so on) 
to connect them, or did you directly connect vifs from different domUs 
without involving dom0?

> 1. When pinging from A to E (or E to A) the first ping takes ~ 34ms,
> following pings take ~0.8ms then after about 10 packets it goes up to
> ~30ms, then it goes back to normal again and back up at a random time
> later, and so on. So I get these random spikes.
> 2. After a random number of packets (usually about 30) the pings stop
> being delivered to E (when sending to A) this happens for a long time
> then randomly a batch (usually 10-20) arrive then it goes again, and
> so on. This is so bad that the packet loss over ~1500 packets is 85%
>
> I am at a loss as to how to fix this - but it's a serious problem
> (obviously) as was intending to use Xen for a network QoS simulation

Networking problems (lost pings, NFS issues, SSH hanging, ...) with xen-2.0.x 
were reported quite often in the last few weeks, search for those threads, 
some of them contained some "magic" you might try, like disabling checksum 
offloading, etc...

Otherwise: try xen 3, or don't run services requiring reliable networking 
inside domU on xen 2 :(

I'm running several database applications inside domUs, they're more demanding 
in terms of HDD IO and CPU, so the networking issues don't affect me that 
much, but if you find a solution, let me know :)

/Ernst

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