Integrating Red Hat Virtualization into your network architecture is a complicated process and depending upon your infrastructure, may require custom configuration to deploy multiple Ethernet interfaces and setup bridging.

Each domain network interface is connected to a virtual network interface in dom0 by a point to point link. These devices are named as vif <domid>.<vifid>. For example, vif1.0 represents the first interface in the first domain; vif3.1 represents the second interface in the third domain.

dom0 handles traffic on these virtual interfaces by using standard Linux conventions for bridging, routing, rate limiting, etc. The xend daemon employs two shell scripts to perform initial configuration of your network and new virtual interfaces. These scripts configure a single bridge for all virtual interfaces. You can configure additional routing and bridging by customizing these scripts.

Red Hat Virtualization's virtual networking is controlled by the two shell scripts, network-bridge and vif-bridge. xend calls these scripts when certain events occur. Arguments can be passed to the scripts to provide additional contextual information. These scripts are located in the /etc/xen/scripts directory. You can change script properties by modifying the xend-config.sxp configuration file located in the /etc/xen directory.

Use the network-bridge command when xend is started or stopped, this script initializes or shuts down the virtual network. Then the configuration initialization creates the bridge xenbr0 and moves eth0 onto that bridge, modifying the routing accordingly. When xend finally exits, it deletes the bridge and removes eth0, thereby restoring the original IP and routing configuration.

vif-bridge is a script that is invoked for every virtual interface on the domain. It configures firewall rules and can add the vif to the appropriate bridge.

There are other scripts that you can use to help in setting up Red Hat Virtualization to run on your network, such as network-route, network-nat, vif-route, and vif-nat. Or these scripts can be replaced with customized variants.