Setting up bridged network with XEN Dom0 and DomU (VM) on different network subnets

Not a very experienced XEN user here.

I wanted to set up an Opensuse 13.1 XEN server with a SLES_11 VM running my mailserver. My idea was to have the VM running a static IP and the Dom0 machine picking up a dynamic IP from my internet provider.

I set up the system initially using YAST with both the Dom0 and DomU running a static IP address on the same netmask 255.255.255.0 subnet. Everything worked fine.

I then changed the Dom0 system so the network card and XEN bridge both got their IP address from DHCP. Because of my internet providers network configuration, that meant the dynamic IP address was completely different from the static IP address.

Specifically:
- DHCP assigned IP for Dom0 - 97.79.x.y
- Static IP assigned to VM - 71.40.a.b

Result:
- Dom0 can "see" the internet fine
- Dom0 can not ping the VM (ping command just hangs with no error message)
- VM - can't ping Dom0 or outside world. (ping command gives destination host unreachable)

It looks to me like network packets aren't crossing the xen bridge and possibly the kernel routing table(s) are messed up. I tried several variations of route options without success on both the VM and Dom0.

Questions:
-Is it even possible to run XEN bridge this way?
-Are the ethernet packets "crossing" the XEN bridge affected by the Dom0 kernel routing parameters?
- Any suggestions to fix?