8.2 HSRP Configuration
8.2.1 Configuring HSRP
To configure a router as a member of an HSRP standby group, enter the following command in interface configuration mode.

Router(config-if)#standby group-number ip virtual-ip-address

Variable  Definition
group-number  (Optional) Indicates the HSRP group to which this interface belongs; specifying a unique group number in the standby commands enables the creation of multiple HSRP groups; the default group is 0
ip-address  Indicates the IP address of the virtual HSRP router

In 12.1.3.T software or higher, HSRP has been changed to support ICMP redirect and disabling of ICMP redirects is no longer required. While running HSRP, it is important that the end-user stations do not discover the actual MAC addresses of the routers as the destination MAC for the default gateway. Any protocol that informs a host of the actual address of the router must be disabled. To ensure that the actual addresses of the participating HSRP routers are not discovered, enabling HSRP on a Cisco router interface automatically disables ICMP redirects on that interface.

When the standby ip command is issued, the interface changes to the appropriate state. The Figure to the left shows an example of the state message generated after enabling HSRP. This message is automatically generated upon successful execution of the command.

The following example shows Router-A interface FastEthernet 0/0 is a member of the HSRP standby group 50, the virtual router IP address for that group is 10.1.1.1, and that ICMP redirects are disabled.

To remove an interface from an HSRP group, enter the no standby group ip command.