Cisco Systems BC-281 Ethernet Redundancy, Configures transparent redundancy, Backup Peers, BC-305

Configuring Data-Link Switching Plus

DLSw+ Configuration Task List

Ethernet Redundancy

The DLSw+ Ethernet Redundancy feature, introduced in Cisco IOS Release 12.0(5)T, provides redundancy and load balancing between multiple DLSw+ peers in an Ethernet environment. It enables DLSw+ to support parallel paths between two points in an Ethernet environment, ensuring resiliency in the case of a router failure and providing load balancing for traffic load. The feature also enables DLSw+ to support multiple DLSw+ routers on the same transparent bridged domain that can reach the same MAC address in a switched environment.

To enable the DLSw+ Ethernet Redundancy feature, issue the following command in interface configuration mode:

Command	Purpose
Router(config-if)# dlsw transparent	Configures transparent redundancy.
redundancy-enable

To enable the DLSw+ Ethernet Redundancy feature in a switched environment, enter the following commands in interface configuration mode:

	Command	Purpose
Step 1
	Router(config-if)# dlsw transparent	Enables DLSw+ Ethernet Redundancy feature when using a switch
	switch-support	device.
Step 2
	Router(config-if)# dlsw transparent	Configures a single destination MAC address to which multiple MAC
	map local mac mac address remote mac	addresses on a transparent bridged are mapped.
	mac address neighbor mac address

The Ethernet Redundancy feature is a complex feature. See the DLSw+ Design and Implementation Guide for more details. Refer to the “DLSw+ with Ethernet Redundancy Configuration Example” section on page 331 and the “DLSw+ with Ethernet Redundancy Enabled for Switch Support Configuration Example” section on page 332 for sample configurations.

Backup Peers

The backup-peeroption is common to all encapsulation types on a remote peer and specifies that this remote peer is a backup peer for the router with the specified IP-address, Frame Relay Data-Link Control Identifier (DLCI) number, or interface name. When the primary peer fails, all circuits over this peer are disconnected and the user can start a new session via their backup peer. Prior to Cisco IOS

Release 11.2(6)F, you could configure backup peers only for primary FST and TCP.

Also, when you specify the backup-peeroption in a dlsw remote-peer tcp command, the backup peer is activated only when the primary peer becomes unreachable. Once the primary peer is reactivated, all new sessions use the primary peer and the backup peer remains active only as long as there are LLC2 connections using it. You can use the linger option to specify a period (in minutes) that the backup peer remains connected after the connection to the primary peer is reestablished. When the linger period expires, the backup peer connection is taken down.

	Cisco IOS Bridging and IBM Networking Configuration Guide
78-11737-02		BC-305