The Xen dom0 infrastructure provides for a bridged networking setup using shell scripts to configure the bridging device properly and attach the domUs' virtual interfaces to the bridge. However, we've seen problems when using this approach, so to solve these issues, instead suggest the following configuration method (to achieve the same thing).

This is for a Debian dom0.

/etc/network/interfaces

Comment out everything referencing your physical devices. Add this:

auto br0
iface br0 inet dhcp
    bridge_ports regex (eth|vif).* noregex

... or if you want to do the manual configuration dance:

auto br0
iface br0 inet static
    bridge_ports regex (eth|vif).* noregex
    address 192.168.10.60
    netmask 255.255.255.0
    [...]

This needs a version of the bridge-utils package more recent than the current Debian stable one (Debian bug #405215). (It's trivial to rebuild the dpkg of, e.g., the Debian testing one on Debian stable.)

/etc/xen/xend-config.sxp

Make sure that only (network-script network-dummy) and (vif-script vif-bridge) are activated and all other (network-script network-WHATEVER), respective (vif-script vif-WHATEVER) are commented out.

Sample configuration files on Debian Lenny

/etc/xen/hurd on dom0

kernel = "/boot/gnumach-xen"
memory = 256
disk = ['phy:sda5,hda,w']
extra = "root=device:hd0"
vif = [ 'mac=00:16:3e:00:00:00, bridge=br0' ]
ramdisk = "/boot/hurd-modules"

/dev/sda5 is an extended partition. br0 is bridge interface on dom0.

/etc/xen/xend-config.sxp on dom0

(network-script 'network-bridge netdev=br0')
(dom0-min-mem 196)
(dom0-cpus 0)
(vncpasswd '')

/etc/network/interfaces on dom0

auto br0
  iface br0 inet static
    address 192.168.1.211
    network 192.168.1.0
    netmask 255.255.255.0
    broadcast 192.168.1.255
    gateway 192.168.1.1
    bridge_ports eth1

eth1 is the interface that is connected to the Internet on the LAN:

Doing settrans on domU

settrans -fgap /servers/socket/2 /hurd/pfinet -i /dev/eth0 -a 192.168.1.210 -g 192.168.1.1 -m 255.255.255.0

/sbin/ifconfig on dom0

br0       Link encap:Ethernet  HWaddr 00:19:d1:2e:06:33  
          inet addr:192.168.1.211  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::219:d1ff:fe2e:633/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:14187 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9214 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:936563 (914.6 KiB)  TX bytes:746184 (728.6 KiB)

eth1      Link encap:Ethernet  HWaddr 00:19:d1:2e:06:33  
          inet6 addr: fe80::219:d1ff:fe2e:633/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:34339 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18526 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3019251 (2.8 MiB)  TX bytes:1453672 (1.3 MiB)