Re: VLAN and bridging with xen

Greg Brackley wrote:
> I'm trying to get a bridging and VLAN working together with an unexpected
> lack of success.  ICMP pings are working well, but UDP traffic isn't
> working. Without the VLAN interface I can get my XEN/bridging networking
> working (but limited by the number of physical interfaces).  Without the 
> XEN
> interfaces I regularly setup VLAN interfaces, as well as using 802.3ad
> bonding. However I seem to be unable to get the bridges to XEN interfaces
> working with VLAN's.
> 
> I'm trying to bridge the traffic from the VLAN interface to a xen vif
> interface. I only have IP addresses on the virtual Ethernet interfaces (in
> the xen vm's). I've got a default MTU of 1500.
> 
> The machine is a dual Opteron, with PCIe SK-9E22 dual GbE (I also have a
> Intel Pro/1000 dual MT in the machine, but it seems to display the same
> issue). The kernel is 2.6.12.6 from xen 3.0 unstable. The installation is
> Fedora Core 4, x86_64. The switch is a Dell 5324. No firewall rules. No
> bridge filtering.
> 
> I'm getting desperate to find a fix. I've been trying to work through this
> for a few weeks, and I've made very little progress. I can provide traffic
> dumps or any other information. Any help would be appreciated. I must be
> missing something simple.

What 'driver' does Xen use for ethernet?  It's likely that this driver
has some hard-coded constraints on packet size that does not take the
extra 4 byte VLAN header into account.

Or, it could be a checksum support issue or similar.

You probably should cross-post this with the bridging and/or xen mailing
lists...or just send to [email protected]
(I think this is probably more a Xen/Bridging problem than VLANs, though
it's possible there is a nasty interaction between all three.)

Ben


-- 
Ben Greear <[email protected]>
Candela Technologies Inc  http://www.candelatech.com