Cisco IOS Software Releases 12.4 T

FHRP - HSRP Multiple Group Optimization

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FHRP - HSRP Multiple Group Optimization

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FHRP - HSRP Multiple Group Optimization

FHRP - HSRP Multiple Group Optimization

Increasingly, many hundreds of subinterfaces are being configured on the same physical interface, with each subinterface having its own HSRP group. The negotiation and maintenance of multiple HSRP groups can have a detrimental impact on network traffic and CPU utilization.

Only one HSRP group is required on a physical interface for the purposes of electing active and standby routers. This group is known as the `master' group. Other HSRP groups may be created on each subinterface and linked to the master group via the group name. These linked HSRP groups are known as `client' or `follow' groups.

The HSRP group state of the client groups follows that of the master group. Client groups do not participate in any sort of router election mechanism.

Client groups send periodic messages in order to refresh their virtual MAC addresses in switches and learning bridges. The refresh message may be sent at a much lower frequency compared with the protocol election messages sent by the master group.

Configuration Information

Configuration information is included in the "Configuring HSRP" chapter in the Cisco IOS Application Services Configuration Guide, Release 12.4T, at the following URL:

Command Reference Information

Command reference information is included in the Cisco IOS IP Application Services Command Reference, Release 12.4T, at the following URL:

New or Modified Commands

The following commands are new or modified for this feature:

show standby

standby follow

List of All Release 12.4T Commands

An alphabetical list of all Cisco IOS Release 12.4T commands is in the Cisco IOS Master Command List, Release 12.4T, at the following URL

List of All New, Modified, Removed, and Replaced Release 12.4T Commands

Alphabetized lists of all new, modified, removed, and replaced commands for each Cisco IOS Release 12.4T release are in the Cisco IOS New, Modified, Removed, and Replaced Commands, Release 12.4T, document at the following URL