Hot Standby Router Protocol (HSRP) is a Cisco proprietary protocol that takes two different devices and makes them into one. Configurations make the interfaces appear as if they are all part of one big "virtual router" with the same default gateway. The configuration provides for redundancy in the case of a failed link, failed port or total switch failure.
1). Decide how many groups that you need. The first group is the primary Internet protocol (IP) on the interface. Any additional IPs are secondary entries and each IP has its own group. This group includes the range of IPs that the hosts will also fall under. The first IP of the range is for the standby IP of the "virtual router" and is passed back and forth between the two switches. The next two IPs are for the interface on each router that will participating in the group. All other IPs in the range belongs to the hosts that are connected to the switch.
