Local-Area Networks and LAN Switching - CCIE Routing and Switching Exam Certification Guide - page 149

the specified MAC address, the partner replies with an icanreach frame. The specific sequence
includes a canureach ex (explore) to find the resource and a canureach cs (circuit setup) that
triggers the peering routers to establish a circuit.

NetBIOS circuit establishment is similar, but instead of forwarding a canureach frame that
specifies a MAC address, DLSw routers send a name query (NetBIOS NAME-QUERY) frame
that specifies a NetBIOS name. Instead of an icanreach frame, there is a name recognized
(NetBIOS NAME-RECOGNIZED) frame.

Most DLSw implementations cache information learned as part of the explorer processing
(from the icanreach responses) so that subsequent searches for the same resource do not result
in the sending of additional explorer frames. This is also true with DLSw+.

DLSw Configuration
The basic configuration of DLSw is quite simple. Each router with attached networks is
configured with a local -peer command. Remote peers are configured to remote routers. It is
preferred to use the loopback IP addresses to configure the peers because the DLSw peers stay
connected regardless of the state of local or remote LAN interfaces. For designs with multiple
branches connecting to a hub site, the promiscuous keyword can be used on the hub router's
local-peer command to permit remote peers to connect without having to explicitly configure
each remote peer on the hub router. The configurations of the routers in Figure 4-29 are shown
in this section.

DLSw Example Network

Figure 4-29

Bridge 5 Bridge 6

1

2

10

20

IP WAN

Router A
10.1.1.1

Router B
10.2.1.1

Router C
10.3.1.1

Bridge group 1

The configuration for Router A is displayed in Example 4-11.
Example 4-11 DLSw Configuration of Router A

source-bridge ring-group 10
!
dlsw local-peer peer-id 10.1.1.1 promiscuous

continues