Configuring First Hop Redundancy Protocols in IPv6

The HSRP is an FHRP designed to allow for transparent failover of the first-hop IP router. HSRP provides high network availability by providing first-hop routing redundancy for IP hosts on GigabitEthernet configured with a default gateway IP address. HSRP is used in a group of routers for selecting an active router and a standby router. In a group of router interfaces, the active router is the router of choice for routing packets; the standby router is the router that takes over when the active router fails or when preset conditions are met.

IPv6 hosts learn of available IPv6 routers through IPv6 neighbor discovery RA messages. These are multicast periodically, or may be solicited by hosts. HSRP is designed to provide only a virtual first hop for IPv6 hosts.

An HSRP IPv6 group has a virtual MAC address that is derived from the HSRP group number, and a virtual IPv6 link-local address that is, by default, derived from the HSRP virtual MAC address. Periodic RAs are sent for the HSRP virtual IPv6 link-local address when the HSRP group is active. These RAs stop after a final RA is sent when the group leaves the active state.

Periodic RAs for the interface link-local address stop after a final RA is sent while at least one virtual IPv6 link-local address is configured on the interface. No restrictions occur for the interface IPv6 link-local address other than that mentioned for the RAs. Other protocols continue to receive and send packets to this address.

HSRP uses a priority mechanism to determine which HSRP configured router is to be the default active router. To configure a router as the active router, you assign it a priority that is higher than the priority of all the other HSRP-configured routers. The default priority is 100, so if you configure just one router to have a higher priority, that router will be the default active router.

HSRP IPv6 uses a different virtual MAC address block than does HSRP for IP:

0005.73A0.0000 through 0005.73A0.0FFF (4096 addresses)

Port number 2029 has been assigned to HSRP IPv6.

Cisco Nonstop Forwarding (NSF) and stateful switchover (SSO) are supported on HSRP for IPv6 on VRF interfaces, which makes HSRP for IPv6 VRF-aware.

For further information about SSO and NSF, see " Stateful Switchover " and " Cisco Nonstop Forwarding " in the Cisco IOS XE High Availability Configuration Guide .

HSRP version 2 must be enabled on an interface before HSRP IPv6 can be configured.

If an IPv6 address is entered, it must be link local. There are no HSRP IPv6 secondary addresses.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    standby version {1| 2

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	interface type number Example: Router(config)# interface GigabitEthernet 0/0/0	Specifies an interface type and number, and places the router in interface configuration mode.
Step 4	standby version {1| 2 Example: Router(config-if)# standby version 2	Changes the version of the HSRP. Version 1 is the default.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 unicast-routing

4.    interface type number

5.    standby [group-number] ipv6 {link-local-address | autoconfig

6.    standby [group-number] preempt [delay minimum seconds | reload seconds | sync seconds}]

7.    standby [group-number] priority priority

8.    exit

9.    show standby [type number [group]] [all | brief

10.    show ipv6 interface [brief] [interface-type interface-number] [prefix

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	ipv6 unicast-routing Example: Router(config)# ipv6 unicast-routing	Enables the forwarding of IPv6 unicast datagrams. The ipv6 unicast-routing command must be enabled for HSRP for IPv6 to work.
Step 4	interface type number Example: Router(config)# interface GigabitEthernet 0/0/0	Specifies an interface type and number, and places the router in interface configuration mode.
Step 5	standby [group-number] ipv6 {link-local-address | autoconfig Example: Router(config-if)# standby 1 ipv6 autoconfig	Activates the HSRP in IPv6.
Step 6	standby [group-number] preempt [delay minimum seconds | reload seconds | sync seconds}] Example: Router(config-if)# standby 1 preempt	Configures HSRP preemption and preemption delay.
Step 7	standby [group-number] priority priority Example: Router(config-if)# standby 1 priority 110	Configures HSRP priority.
Step 8	exit Example: Router(config-if)# exit	Returns the router to privileged EXEC mode.
Step 9	show standby [type number [group]] [all | brief Example: Router# show standby	Displays HSRP information.
Step 10	show ipv6 interface [brief] [interface-type interface-number] [prefix Example: Router# show ipv6 interface GigabitEthernet 0/0/0	Displays the usability status of interfaces configured for IPv6.