Configuring Transparent Bridging
Transparent and SRT Bridging Configuration Task List
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Cisco IOS Bridging and IBM Networking Configuration Guide
Support for RFC 1483 was added in Cisco IOS Release 12.0(3)T, enabling transparent bridging between
Token Ring LANs (using AAL5-SNAP PVCs) and LANs, VLANs or ELANS (using bridged PDUs).
RFC 1483 defines an encapsulation type for transferring LAN data via ATM networks.
For more information on configuring ATM, refer to the “Configuring ATM” chapter in the Cisco IOS
Wide-Area Networking Configuration Guide.
Configuring Transparent Bridging over DDR
The Cisco IOS software supports transparent bridging over dial-on-demand routing (DDR) and provides
you some flexibility in controlling access and configuring the interface.
To configure DDR for bridging, complete the tasks in the following sections:
•Defining the Protocols to Bridge
•Specifying the Bridging Protocol
•Determining Access for Bridging
•Configuring an Interface for Bridging
For an example of configuring transparent bridging over DDR, see the section “Transparent Bridging
over DDR Examples” section.
Defining the Protocols to Bridge
IP packets are routed by default unless they are explicitly bridged; all others are bridged by default unless
they are explicitly routed.
To bridge IP packets, use the following command in global configuration mode:
If you choose not to bridge another protocol, use the relevant command to enable routing of that protocol.
For more information about tasks and commands, refer to the relevant protocol chapters in the following
publications:
•Cisco IOS IP and IP Routing Configuration Guide
•Cisco IOS AppleTalk and Novell IPX Configuration Guide
•Cisco IOS Apollo Domain, Banyan VINES, DECnet, ISO CLNS, and XNS Configuration Guide
Specifying the Bridging Protocol
You must specify the type of spanning-tree bridging protocol to use and also identify a bridge group. To
specify the Spanning-Tree Protocol and a bridge group number, use the following command in global
configuration mode:
The bridge-group number is used when you configure the interface and assign it to a bridge group.
Packets are bridged only among members of the same bridge group.
Command Purpose
no ip routing Disables IP routing.
Command Purpose
bridge bridge-group protocol {ieee | dec |
vlan-bridge}
Defines the type of spanning tree protocol and identify a bridge group.