Hands-On Lab: Configuring HSRP for IPv6

Lab Objective

Configure HSRP for IPv6 on two routers using the autoconfig option to automatically generate a virtual link-local address, verify Active and Standby roles form correctly, and confirm failover behavior when the active router fails.

Lab Purpose

HSRP for IPv6 follows the same underlying active/standby logic as HSRP for IPv4, discussed earlier in this series, but offers a convenience unique to IPv6: rather than requiring an administrator to choose and configure a virtual IP address, HSRPv6 can automatically derive one using the same well-known virtual MAC address convention IPv6 itself uses for link-local addressing.

Lab Topology

R1 (intended active) ---- Gi0/1 ---- Switch1
R2 (intended standby) ---- Gi0/1 ---- Switch1

R1: 2001:DB8:H:1::2/64
R2: 2001:DB8:H:1::3/64
PC: 2001:DB8:H:1::10/64

Task 1: Configure Basic IPv6 Addressing

Enable IPv6 routing and configure both routers' interfaces on the shared segment.

Task 2: Configure HSRP for IPv6 on R1 Using Autoconfig

Configure HSRP version 2 for IPv6 on R1, using the autoconfig keyword rather than manually specifying a virtual address, with a higher priority.

Task 3: Configure HSRP for IPv6 on R2

Configure the matching HSRP group on R2 with default priority.

Task 4: Verify the Autogenerated Virtual Address and Roles

Confirm both routers agree on the automatically generated virtual address, and that R1 is Active with R2 as Standby.

Task 5: Simulate a Failure and Verify Failover

Shut down R1's interface and confirm R2 becomes Active.

Solution and Verification

R1(config)# ipv6 unicast-routing
R1(config)# interface gigabitethernet0/1
R1(config-if)# ipv6 address 2001:DB8:H:1::2/64
R1(config-if)# no shutdown

R2(config)# ipv6 unicast-routing
R2(config)# interface gigabitethernet0/1
R2(config-if)# ipv6 address 2001:DB8:H:1::3/64
R2(config-if)# no shutdown

R1(config)# interface gigabitethernet0/1
R1(config-if)# standby version 2
R1(config-if)# standby 1 ipv6 autoconfig
R1(config-if)# standby 1 priority 150
R1(config-if)# standby 1 preempt

-- "autoconfig" tells HSRP to derive the
-- virtual IPv6 address automatically,
-- rather than the administrator specifying
-- one manually as with IPv4 HSRP

R2(config)# interface gigabitethernet0/1
R2(config-if)# standby version 2
R2(config-if)# standby 1 ipv6 autoconfig

R1# show standby ipv6 brief

Interface  Grp  Pri P State   Active   Standby   Virtual IP
Gi0/1      1    150 P Active  local    FE80::3   FE80::5:73FF:FEA0:1

R2# show standby ipv6 brief

Interface  Grp  Pri P State     Active     Standby  Virtual IP
Gi0/1      1    100   Standby   FE80::2    local    FE80::5:73FF:FEA0:1

-- Both routers independently derived and
-- agree on the identical virtual link-local
-- address, without either administrator
-- ever typing it manually

R1(config)# interface gigabitethernet0/1
R1(config-if)# shutdown

R2# show standby ipv6 brief

Interface  Grp  Pri P State   Active   Standby  Virtual IP
Gi0/1      1    100   Active  local    unknown  FE80::5:73FF:FEA0:1
-- R2 automatically became Active

Key Takeaway

HSRPv6's autoconfig option leverages the same virtual MAC address concept underlying IPv6's own address autoconfiguration, discussed earlier in this series regarding SLAAC — both routers deterministically derive the identical virtual address from the well-known HSRP virtual MAC without any coordination beyond configuring the same group number, eliminating the administrator's need to plan and manually assign a specific virtual address as required with IPv4 HSRP.