Symptom

- CAT8500 is not responding to unicast ARP request (ARP probe), when the request is coming for its HSRP virtual IP. HSRP is enabled on subinterface. - If the ARP request is broadcast and destined to the HSRP vIP on CAT8500, the router replies back without issues. - If the ARP probe is destined to physical IP addresses on the CAT8500, router replies back without issue.

Conditions

- CAT8500 router running IOS-XE 17.9.2/17.9.1 + HSRP enabled on subinterface. - Unicast ARP request (ARP probe) is destined to the HSRP vIP on CAT8500 router.

Workaround

- Clear arp table.

Further Problem Description