[Xen-users] Suspected network problem after domUs come online

[Gerard Beekmans <gerard@xxxxxxxxxxxxxxxxx>]

Hi guys,

I've been experiencing intermittent network problems. I can't be sure if they are caused by Xen or if using Xen simply aggravates an existing problem (ie: hardware, driver, software bug, etc) but I thought I'd run it by you guys in hopes of getting some ideas.

I've narrowed down the problem to be related to the named daemon from bind9. This may not exclusively be a "named" problem. Other daemons could be affected but I don't have any others installed yet.

The symptoms are as follows: extremely slow network with a lot of dropped packets. I can't actually test the machine locally without having to go over the network because the server is remote from me. Based on the load averages alone, it appears it's otherwise responsive. Pings to local IP addresses aren't dropped. Only when the traffic has to leave the physical machine.

Shutting down named makes the problem go away. Sometimes I can run it for a few hours or a day before it starts acting up. Once it acts up like this the only way I can run named again is by rebooting the physical machine (dom0) and restart the domUs.

Pertinent system info:

Dom0 and DomUs all running Ubuntu Oneiric with kernel 3.0.0-20. I tried older kernel versions as well with the same issues.

NIC: Intel Gigabit, using the e1000 driver

Network setup is NAT (per requirements of the hosting company I'm with. Routed or bridged isn't an option for the domUs to have Internet access).

I'm focussing my troubleshooting around named and trying to figure out exactly what it's doing that triggers this network problem. Do any of you have suggestions, ideas or a fix if this is a known problem?

If you need additional information, please let me know.

Thanks,

--

Gerard Beekmans

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