Cisco Systems 3560-X, 3750-X Configuring HSRP

CHAPT ER

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

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Configuring HSRP

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

or 3560-X switch to provide routing redundancy for routing IP traffic without being dependent on the

availability of any single router.Unless otherwise noted, the term switch refers to a Catalyst 3750-X

or 3560-X standalone switch and to a Catalyst 3750-X 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. If the switch is running the LAN base feature set, only Layer 2 mode is supported.

For complete syntax and usage information for the commands used in this chapter, see these documents:

• Switch command reference for this release

• Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2 at

http://www.cisco.com/en/US/docs/ios/12_2/ipaddr/command/reference/fipras_r.html

• Hot Standby Router Protocol Version 2 feature module at

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gthsrpv2.html

This chapter consists of these sections:

• Understanding HSRP, page 44-1

• Configuring HSRP, page 44-5

• Displaying HSRP Configurations, page 44-13

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.