FC4, Xen bridging not working

[Harry Hoffman <hhoffman ip-solutions net>]

hi, just got fc4 and xen working. i'm in dom0 and can see the bridge setup
and ifconfig shows it's up.

trying pinging across to the default gateway and I get nothing (echo reply
is not blocked)

stop iptables to make sure that's not it and run into the same thing.

restarted switch in case it was an arp cache issue, no dice.

changed xend-config.sxp from bridging to routing, reboot, still no network
connectivity.

reboot to standard kernel all works well.

any ideas?

TIA,
Harry