Is it possible to run HSRP and OSPF together on the backbone router?
A. HSRP and OSPF are two different protocols. The OSPF that runs on the router advertises the two physical interfaces and not the virtual IP address. When this router becomes active, it broadcasts a gratuitous ARP packet with the HSRP virtual MAC address to the affected LAN segment. If the segment uses an Ethernet switch, this allows the switch to change the location of the virtual MAC address so that packets go to the new router instead of the one that is no longer active. End devices do not actually need this gratuitous ARP if the routers use the default HSRP MAC address.
