Cisco IOS Cookbook, 2nd Edition

Configuring DLSw

Problem

You want to set up DLSw to allow Token Ring bridging through an IP network.

Solution

There are many different ways to configure two routers to allow Token Ring to Token Ring bridging through DLSw. The most common reason for doing this is to allow Token Ring SNA LLC2 devices to communicate with a mainframe Front End Processor (FEP) attached to another Token Ring. It is relatively common to have many remote rings connecting to a single central ring. In cases like this, it is often best to use one or more dedicated DLSw routers at the central location. The CPU overhead required for supporting a large number of DLSw connections can be relatively high, so it is useful to restrict this functionality to special purpose DLSw routers and keep it off of routers that also need to handle core routing functions.

Here is the DLSw configuration for central router, which is the one that connects directly to the ring that holds the FEP:

dlsw-central(config)#interface Loopback0
dlsw-central(config-if)#ip address 10.1.1.5 255.255.255.252
dlsw-central(config-if)#exit
dlsw-central(config)#access-list 701 permit 4000.3745.AAAA 8000.0000.0000
dlsw-central(config)#source-bridge ring-group 101
dlsw-central(config)#dlsw local-peer peer-id 10.1.1.5 promiscuous
dlsw-central(config)#dlsw timer explorer-wait-time 5
dlsw-central(config)#dlsw icanreach mac-exclusive
dlsw-central(config)#dlsw icanreach mac-address 4000.3745.AAAA mask ffff.ffff.ffff
dlsw-central(config)#dlsw cache-ignore-netbios-datagram ...