Re: [Xen-users] Slow windows network with gplpv driver.

[John Weekes <lists.xen@xxxxxxxxxxxxxxxxxx>]

On 3/3/2011 10:49 PM, James Harper wrote:

Have you tried changing the MAC address on the virtual network
>  interfaces for these slow domains? I had one customer who was seeing
>  only 10 Mbps, and adjusting the MAC address to anything else fixed it.

I

>  still do not know why that was the case, but some limitation in Xen or

a

>  driver seemed to have been at play.
> 

This could happen if the user thought they could make up any random MAC
address. Certain bits in the MAC address indicate multicast and
broadcast address types, and setting one of those could have nasty
consequences for the whole network.

The MAC in question started with the QEMU first bytes. It looked something like this, but with a different last three bytes:

52:54:00:68:0C:E5

Would anything in those last three bytes cause an issue?

Since then, I have switched to using Xen MACs (starting with 00:16:3E), though I don't know if this will matter.

-John

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