Cisco Systems 3750E manual Standby group-number authentication string, Holdtime, 40-10

Chapter 40 Configuring HSRP and Enhanced Object Tracking

Configuring HSRP

When configuring these attributes, follow these guidelines:

•The authentication string is sent unencrypted in all HSRP messages. You must configure the same authentication string on all routers and access servers on a cable to ensure interoperation. Authentication mismatch prevents a device from learning the designated Hot Standby IP address and timer values from other routers configured with HSRP.

•Routers or access servers on which standby timer values are not configured can learn timer values from the active or standby router. The timers configured on an active router always override any other timer settings.

•All routers in a Hot Standby group should use the same timer values. Normally, the holdtime is greater than or equal to 3 times the hellotime.

Beginning in privileged EXEC mode, use one or more of these steps to configure HSRP authentication and timers on an interface:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	interface interface-id	Enter interface configuration mode, and enter the HSRP
		interface on which you want to set authentication.
Step 3
	standby [group-number]authentication string	(Optional) authentication string—Enter a string to be carried in
		all HSRP messages. The authentication string can be up to eight
		characters in length; the default string is cisco.
		(Optional) group-number—The group number to which the
		command applies.
Step 4
	standby [group-number]timers hellotime	(Optional) Configure the time between hello packets and the
	holdtime	time before other routers declare the active router to be down.
		• group-number—The group number to which the command
		applies.
		• hellotime—The hello interval in seconds. The range is from
		1 to 255; the default is 3 seconds.
		• holdtime—The time in seconds before the active or standby
		router is declared to be down. The range is from 1 to 255;
		the default is 10 seconds.
Step 5
	end	Return to privileged EXEC mode.
Step 6
	show running-config	Verify the configuration of the standby groups.
Step 7
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

Use the no standby [group-number] authentication string interface configuration command to delete an authentication string. Use the no standby [group-number] timers hellotime holdtime interface configuration command to restore timers to their default values.

This example shows how to configure word as the authentication string required to allow Hot Standby routers in group 1 to interoperate:

Switch# configure terminal

Switch(config)# interface gigabitethernet1/0/1

Switch(config-if)# no switchport

Switch(config-if)#standby 1 authentication word

Switch(config-if)# end

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
40-10	OL-9775-02