Configuring Transparent Bridging
Transparent and SRT Bridging Configuration Task List
BC-40
Cisco IOS Bridging and IBM Networking Configuration Guide
Assigning a Bridge Group Number and Defining the Spanning-Tree Protocol
Prior to configuring the router for integrated routing and bridging, you must enable bridging by setting
up a bridge group number and specifying a Spanning-Tree Protocol. You can choose either the IEEE
802.1D Spanning-Tree Protocol or the earlier Digital protocol upon which this IEEE standard is based.
To assign a bridge group number and define a spanning tree protocol, use the following command in
global configuration mode:
The IEEE 802.1D Spanning-Tree Protocol is the preferred way of running the bridge. Use the Digital
Spanning-Tree Protocol only for backward compatibility.
Configuring Interfaces
To configure a router interface in the Cisco IOS software, use the following commands beginning in
global configuration mode:
Enabling Integrated Routing and Bridging
After you have set up the interfaces in the router, you can enable integrated routing and bridging.
To enable integrated routing and bridging in the Cisco IOS software, use the following command in
global configuration mode:
Use the show interfaces irb privileged EXEC command to display the protocols that a given bridged
interface can route to the other routed interface when the packet is routable, and to display the protocols
that a given bridged interface bridges.
Configuring the Bridge-Group Virtual Interface
The bridge-group virtual interface resides in the router. It acts like a normal routed interface that does
not support bridging, but represents the entire corresponding bridge group to routed interfaces within the
router. The bridge-group virtual interface is assigned the number of the bridge group that it represents.
The bridge-group virtual interface number is the link between the bridge-group virtual interface and its
bridge group. Because the bridge-group virtual interface is a virtual routed interface, it has all the
network layer attributes, such as a network address and the ability to perform filtering. Only one
bridge-group virtual interface is supported for each bridge group.
Command Purpose
bridge bridge-group protocol {ieee | dec |
vlan-bridge}
Assigns a bridge group number and defines a Spanning-Tree Protocol.
Command Purpose
Step1 interface type number Specifies the interface and enters interface configuration mode.
Step2 port Specifies concentrator port operation.
Step3 bridge-group bridge-group Assigns bridge-groups to appropriate interfaces.
Command Purpose
bridge irb Enables integrated routing and bridging.