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| 6.4 |  | HSRP Configuration |
| 6.4.1 |  | 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

- 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 zero.
- 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. Prior versions of the IOS require disabling of ICMP redirects. While running HSRP, it is important that the end-user stations are not able to 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.

The standby ip command changes the interface to the appropriate state. Figure shows an example of the state message, automatically generated upon successful enabling of HSRP.

Output from the show running-config command shows the following:

- Interface FastEthernet 0/0 is a member of HSRP standby group 50.
- The virtual router IP address is 10.1.1.1.
- ICMP redirects are disabled.

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