I've setup a VM running Windows Server 2008 on a host node running Xen 3.4.3-5 and the following kernel: 2.6.18-308.1.1.el5xen #1 SMP Wed Mar 7 05:38:01 EST 2012 i686 i686 i386 GNU/Linux

The network speed on the VM is very slow--using the online speed tests I can only get it up to 8-9mbps. The line is 100mbps burstable and the host node has no problem achieving those speeds. If it setup a VM running CentOS, it too has no problems achieving those speeds.

I've done some pretty exhaustive troubleshooting, but nothing has helped:

• New VM installations of Win2k8 do have the same network problem.
• Upgrading to most recent kernel-xen did not help (2.6.18-308.1.1.el5xen).
• Upgrading from xen 3.4.0 to xen 3.4.3-5 did not help.
• Disabling Windows firewall, etc did not help.
• Changing network card device config from auto negotiation to manually be 100mbps full duplex did not help.
• Changing the network receive buffer packet size did not help (tried all combos from 64k to 8k).

At this point I'm pretty much out of ideas--any help would be appreciated!