Xen users - Jun 2010 - xcp - windows networking problem

Hi,

I''m having problems getting the networking to work properly with
Windows
(Server 2003 R2 x64) on XCP 0.1.1. I have been working on this for a while,
but I''m unable to find a consistent pattern. However this is what
I''ve found
so far:

The nature of the problem is that traffic some protocols (HTTP, JPDA) hardly
gets through; parts of a web page will load, but the whole page never
completes and the browser just hangs forever. The Java debugger will connect
to a remote process, but it will be unable to step correctly through the
code and eventually it looses the connection. Other protocols (RDP, ICMP
ping) works fine AFAICT, though I am experiencing some disconnects when
using RDP.

I believe the problem is caused by the Citrix XenServer PV Drivers, though
not consistently. I now have two identical Windows 2003 servers, one where
the networking is working with Citrix PV, another where it is broken using
the same driver. When i uninstall the Citrix PV drivers on the
"broken"
server, so that the Realtek RTL8139 network driver is used, the problem goes
away.

Strangely, the network on the "broken" server works fine when I
connect
directly from a different VM on the same LAN/pool. Only when I connect from
the outside through a firewall (which is also running as a VM on the LAN) I
experience the problem. Could it be that packets are sent too quickly,
resulting in packet loss?

I suspected the problem being caused by two virtual machines running on the
same host, but that does not seem to be the case either as I''ve moved
the
firewall to a different host than the Windows server is running on, without
any impact on the problem.

A while ago I tried the GPLPV drivers but that did not solve the problem.
I''ll give this another shot at some point. I''ve also verified
the problem on
two distinctly different hardware platforms.

Has anyone had similar experiences, and do you have a suggestion for solving
the issue?

Many thanks for your help!

Trygve

-- 
HypoBytes Ltd.
Trygve Sanne Hardersen
Akersveien 24F
0177 Oslo
Norway

hypobytes.com
+47 40 55 30 25


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> 
> A while ago I tried the GPLPV drivers but that did not solve the
problem. I''ll
> give this another shot at some point. I''ve also verified the
problem
on two
> distinctly different hardware platforms.
> 
When you tried the GPLPV drivers, did you try turning off any offload
functions in the adapter properties under Windows? The Citrix drivers
probably offer the same switches to turn off.

Jame

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On Thu, Jun 3, 2010 at 12:10 PM, James Harper
<james.harper@bendigoit.com.au
> wrote:
> >
> > A while ago I tried the GPLPV drivers but that did not solve the
> problem. I''ll
> > give this another shot at some point. I''ve also verified the
problem
> on two
> > distinctly different hardware platforms.
> >
>
> When you tried the GPLPV drivers, did you try turning off any offload
> functions in the adapter properties under Windows? The Citrix drivers
> probably offer the same switches to turn off.
>
Haven''t tried tweaking these settings, but I did check that they were
the
same on the working and broken VMs. Will do some more testing and let you
know what I find.

Thanks!

Trygve


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>
>> When you tried the GPLPV drivers, did you try turning off any offload
>> functions in the adapter properties under Windows? The Citrix drivers
>> probably offer the same switches to turn off.
>>
>
> Haven''t tried tweaking these settings, but I did check that they
were the
> same on the working and broken VMs. Will do some more testing and let you
> know what I find.
>
>
Turning off "Large send offload" indeed solves the problem. Many
thanks!

Trygve


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