Configuring Token Ring Inter-Switch Link
TRISL Configuration Task List
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Cisco IOS Bridging and IBM Networking Configuration Guide
78-11737-02
Configuring Source-Route Translational Bridging over TRISL
To configure source-route translational bridging over TRISL, use the following commands beginning in
global configuration mode:
Note For a complete description of SR/TLB, including configuring translation compatibility with IBM
8209 bridges and configuring Token Ring LLC2 to Ethernet Type II (0x80d5) and Token Ring LLC2
to Ethernet 802.3 LLC2 (standard) translations, please refer to the “Configuring Source-Route
Bridging” chapter in this publication and “Source-Route Bridging Commands” chapter in the Cisco
IOS Bridging and IBM Command Reference (Volume 1 of 2).
Configuring Automatic Spanning Tree
The automatic spanning-tree function supports automatic resolution of spanning trees in SRB networks,
which provides a single path for spanning explorer frames to traverse from a given node in the network
to another. Spanning explorer frames have a single-route broadcast indicator set in the routing
information field. Port identifiers consist of ring numbers and bridge numbers associated with the ports.
The spanning-tree algorithm for SRB does not support Topology Change Notification Bridge Protocol
Data Unit (BPDU).
Although the automatic spanning-tree function can be configured with Source-Route Translational
Bridging (SR/TLB), the SRB domain and transparent bridging domain have separate spanning trees.
Each Token Ring interface can belong to only one spanning tree. Only one bridge group can run the
automatic spanning-tree function at a time.
To create a bridge group that runs an automatic spanning-tree function compatible with the IBM SRB
spanning-tree implementation, use the following command in global configuration mode:
Command Purpose
Step 1
Router(config)# source-bridge ring-group vring-num
Configures a virtual ring for the router.
Step 2
Router(config)# source-bridge transparent ring-group
pseudoring bridge-number tb-group [oui]
Enables bridging between transparent bridging and
source-route bridging.
Step 3
Router(config)# interface type
slot/port.subinterface-number
Specifies the subinterface on which TRISL will be
used.
Step 4
Router(config-if)# encapsulation tr-isl trbrf-vlan
vlanid bridge-num bridge-number
Defines the encapsulation for TRISL.
Step 5
Router(config-if)# source-bridge trcrf-vlan vlanid
ring-group ring-number
Assigns a VLAN ID to the router’s virtual ring.
Command Purpose
Router(config)# bridge bridge-group
protocol ibm
Creates a bridge group that runs the automatic spanning-tree function.
