Cisco Systems 78-11741-02 manual Configuring Hsrp Group Attributes, IPC-102

Configuring IP Services

Configuring the Hot Standby Router Protocol

Configuring HSRP Group Attributes

To configure other Hot Standby group attributes that affect how the local router participates in HSRP, use the following commands in interface configuration mode as needed:

Command	Purpose
Router(config-if)# standby [group-number] timers	Configures the time between hello packets and the hold time
[msec] hellotime [msec] holdtime	before other routers declare the active router to be down.
Router(config-if)# standby [group-number] priority	Set the Hot Standby priority used in choosing the active
priority	router. The priority value range is from 1 to 255, where 1
	denotes the lowest priority and 255 denotes the highest
	priority. Specify that, if the local router has priority over the
	current active router, the local router should attempt to take its
	place as the active router.
Router(config-if)# standby [group-number] preempt	Configure a preemption delay, after which the Hot Standby
[delay {minimum delay reload delay sync delay}]	router preempts and becomes the active router.
Router(config-if)# standby [group-number] track type	Configures the interface to track other interfaces, so that if
number [interface-priority]	one of the other interfaces goes down, the Hot Standby
	priority of the device is lowered.
Router(config-if)# standby [group-number]	Selects an authentication string to be carried in all HSRP
authentication text string	messages.
Router(config-if)#standby delay minimum min-delay	Configures the delay period before the initialization of Hot
reload reload-delay	Standby Router Protocol (HSRP) groups.
Router(config-if)# standby [group-number] mac-address	Specifies a virtual MAC address for the virtual router.
macaddress
Router(config-if)#standby use-bia [scope interface]	Configures HSRP to use the burned-in address of an interface
	as its virtual MAC address instead of the preassigned MAC
	address (on Ethernet and FDDI) or the functional address (on
	Token Ring).

Changing the HSRP MAC Refresh Interval

When HSRP runs over FDDI, you can change the interval at which a packet is sent to refresh the MAC cache on learning bridges or switches. HSRP hello packets use the burned-in address (BIA) instead of the MAC virtual address. Refresh packets keep the MAC cache on switches and learning bridges current.

You can change the refresh interval on FDDI rings to a longer or shorter interval, thereby using bandwidth more efficiently. You can prevent the sending of any MAC refresh packets if you do not need them (if you have FDDI but do not have a learning bridge or switch). When changing the HSRP MAC refresh interval, be aware of the following guidelines:

•This feature applies to HSRP running over FDDI only.

•You need not configure the MAC refresh interval if you have the standby use-biainterface configuration command configured.

By default, a packet is sent every 10 seconds to refresh the MAC cache on learning bridges or switches. To change the interval, use the following command in interface configuration mode:

Cisco IOS IP Configuration Guide

IPC-102