Cisco Systems 3750E manual Configuring Hsrp and Enhanced Object Tracking, Understanding Hsrp, 40-1

C H A P T E R 40

Configuring HSRP and Enhanced Object Tracking

This chapter describes how to use Hot Standby Router Protocol (HSRP) on the Catalyst 3750-E

or 3560-E switch to provide routing redundancy for routing IP traffic without being dependent on the availability of any single router. It also provides information about configuring enhanced object tracking, that enhances the HSRP tracking mechanism. Unless otherwise noted, the term switch refers to a Catalyst 3750-E or 3560-E standalone switch and to a Catalyst 3750-E switch stack.

You can also use a version of HSRP in Layer 2 mode to configure a redundant command switch to take over cluster management if the cluster command switch fails. For more information about clustering, see Chapter 6, “Clustering Switches” and see the Getting Started with Cisco Network Assistant, available on Cisco.com.

Note For complete syntax and usage information for the commands used in this chapter, see the switch command reference for this release and the Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2.

This chapter consists of these sections:

•Understanding HSRP, page 40-1

•Configuring HSRP, page 40-4

•Displaying HSRP Configurations, page 40-11

•Configuring Enhanced Object Tracking, page 40-12

Understanding HSRP

HSRP is Cisco’s standard method of providing high network availability by providing first-hop redundancy for IP hosts on an IEEE 802 LAN configured with a default gateway IP address. HSRP routes IP traffic without relying on the availability of any single router. It enables a set of router interfaces to work together to present the appearance of a single virtual router or default gateway to the hosts on a LAN. When HSRP is configured on a network or segment, it provides a virtual Media Access Control (MAC) address and an IP address that is shared among a group of configured routers. HSRP allows two or more HSRP-configured routers to use the MAC address and IP network address of a virtual router. The virtual router does not exist; it represents the common target for routers that are configured to provide backup to each other. One of the routers is selected to be the active router and another to be the standby router, which assumes control of the group MAC address and IP address should the designated active router fail.

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

OL-9775-02 40-1