Configuring Transparent Bridging
Transparent and SRT Bridging Configuration Task List
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Cisco IOS Bridging and IBM Networking Configuration Guide
You can configure the Cisco IOS software to route a given protocol among one group of interfaces and
concurrently bridge that protocol among a separate group of interfaces, all within one router. The given
protocol is not switched between the two groups. Rather, routed traffic is confined to the routed
interfaces and bridged traffic is confined to the bridged interfaces. A protocol may be either routed or
bridged on a given interface, but not both.
The concurrent routing and bridging capability is, by default, disabled. While concurrent routing and
bridging is disabled, the Cisco IOS software absorbs and discards bridgeable packets in protocols that
are configured for routing on any interface in the router.
When concurrent routing and bridging is first enabled in the presence of existing bridge groups, it will
generate a bridge route configuration command for any protocol for which any interface in the bridge
group is configured for routing. This is a precaution that applies only when concurrent routing and
bridging is not already enabled, bridge groups exist, and the bridge crb command is encountered.
To enable concurrent routing and bridging in the Cisco IOS software, use the following command in
global configuration mode:
Information about which protocols are routed and which are bridged is stored in a table, which can be
displayed with the show interfaces crb privileged EXEC command.
When concurrent routing and bridging has been enabled, you must configure an explicit bridge route
command for any protocol that is to be routed on the interfaces in a bridge group in addition to any
required protocol-specific interface configuration.
To configure specific protocols to be routed in a bridge group, use the following command in interface
configuration mode:
Configuring Integrated Routing and BridgingPerform one or more of the following tasks to configure integrated routing and bridging on your router:
•Assigning a Bridge Group Number and Defining the Spanning-Tree Protocol
•Configuring Interfaces
•Enabling Integrated Routing and Bridging
•Configuring the Bridge-Group Virtual Interface
•Configuring Protocols for Routing or Bridging
Command Purpose
bridge crb Enables concurrent routing and bridging.
Command Purpose
bridge bridge-group route protocol Specifies a protocol to be routed on a bridge group.