Configuring Transparent Bridging
Transparent and SRT Bridging Configuration Task List
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Cisco IOS Bridging and IBM Networking Configuration Guide
Bridging in a Frame Relay Network with No Multicasts
The Frame Relay bridging software uses the same spanning-tree algorithm as the other bridging
functions, but allows packets to be encapsulated for transmission across a Frame Relay network. You
specify IP-to-data-link connection identifier (DLCI) address mapping and the system maintains a table
of both the Ethernet address and the DLCIs.
To configure bridging in a network that does not support a multicast facility, define the mapping between
an address and the DLCI used to connect to the address. To bridge with no multicasts, use the following
command in interface configuration mode:
An example configuration is provided in the section “Frame Relay Transparent Bridging Examples” at
the end of this chapter. Frame Relay is discussed in more detail in the “Configuring Frame Relay”
chapter in the Cisco IOS Wide-Area Networking Configuration Guide.
Bridging in a Frame Relay Network with Multicasts
The multicast facility is used to learn about the other bridges on the network, eliminating the need for
you to specify any mappings with the frame-relay map bridge broadcast command. An example
configuration is provided in the section “Frame Relay Transparent Bridging Examples” at the end of the
chapter for use as a configuration guide. Frame Relay is discussed in more detail in the “Configuring
Frame Relay” chapter in the Cisco IOS Wide-Area Networking Configuration Guide.
Configuring Transparent Bridging over Multiprotocol LAPB
Cisco IOS software implements transparent bridging over multiprotocol Link Access Protocol-Balanced
(LAPB) encapsulation on serial interfaces. To configure transparent bridging over multiprotocol LAPB,
use the following commands beginning in global configuration mode:
Note Transparent bridging over multiprotocol LAPB requires use of the encapsulation lapb
multi command. You cannot use the encapsulation lapb protocol command with a bridge
keyword to configure this feature.
For an example of configuring transparent bridging over multiprotocol LAPB, see the
“Transparent Bridging over Multiprotocol LAPB Example” section on page76”.
Command Purpose
frame-relay map bridge dlci broadcast Defines the mapping between an address and the DLCI used to
connect to the address.
Command Purpose
Step1 interface serial number Specifies the serial interface.
Step2 no ip address Specifies no IP address to the interface.
Step3 encapsulation lapb multi Configures multiprotocol LAPB encapsulation.
Step4 bridge-group bridge-group Assigns the interface to a bridge group.
Step5 bridge bridge-group protocol {ieee | dec | vlan-bridge}Specifies the type of Spanning-Tree Protocol.