Configuring Transparent Bridging
Transparent and SRT Bridging Configuration Task List
BC-41
Cisco IOS Bridging and IBM Networking Configuration Guide
When you enable routing for a given protocol on the bridge-group virtual interface, packets coming from
a routed interface but destined for a host in a bridged domain are routed to the bridge-group virtual
interface, and are forwarded to the corresponding bridged interface. All traffic routed to the bridge-group
virtual interface is forwarded to the corresponding bridge group as bridged traffic. All routable traffic
received on a bridged interface is routed to other routed interfaces as if it is coming directly from the
bridge-group virtual interface.
To create a bridge-group virtual interface, use the following command in interface configuration mode:
When you intend to bridge and route a given protocol in the same bridge group, you must configure the
network-layer attributes of the protocol on the bridge-group virtual interface. Do not configure protocol
attributes on the bridged interfaces. No bridging attributes can be configured on the bridge-group virtual
interface.
Although it is generally the case that all bridged segments belonging to a bridge group are represented
as a single segment or network to the routing protocol, there are situations where several individual
networks coexist within the same bridged segment. To make it possible for the routed domain to learn
about the other networks behind the bridge-group virtual interface, configure a secondary address on the
bridge-group virtual interface to add the corresponding network to the routing process.
Configuring Protocols for Routing or Bridging
When integrated routing and bridging is enabled, the default route/bridge behavior in a bridge group is
to bridge all packets.
You could then explicitly configure the bridge group to route a particular protocol, so that routable
packets of this protocol are routed, while nonroutable packets of this protocol or packets for protocols
for which the bridge group is not explicitly configured to route will be bridged.
You could also explicitly configure the bridge group so that it does not bridge a particular protocol, so
that routable packets of this protocol are routed when the bridge is explicitly configured to route this
protocol, and nonroutable packets are dropped because bridging is disabled for this protocol.
Note Packets of nonroutable protocols such as LAT are only bridged. You cannot disable
bridging for the nonroutable traffic.
To configure specific protocols to be routed or bridged in a bridge group, use one or more of the
following commands in global configuration mode:
Command Purpose
interface bvi bridge-group Enables a bridge-group virtual interface.
Command Purpose
bridge bridge-group route protocol Specifies a protocol to be routed in a bridge group.
no bridge bridge-group route protocol Specifies that a protocol is not to be routed in a bridge group.
bridge bridge-group bridge protocol Specifies that a protocol is to be bridged in the bridge group.
no bridge bridge-group bridge protocol Specifies that a protocol is not to be bridged in the bridge group.