Cisco Hot Standby Router Protocol

Two routers are connected to the network and the two default gateways do not provide a completely reliable path in the event of an outage.
Although the ITA has some newer IP hosts that support dynamic router discovery with the ICMP Router Discovery Protocol (IRDP), it mostly has a large class of legacy host implementations that do not. These hosts are unable to find a new router when their default gateway becomes unavailable.The ITA is also concerned with IRDP’s administrative and processing overhead, security issues, and lack of support on the legacy platforms.Configuring HSRP on the two routers provides a fast fail-over mechanism that is transparent to the users. This allows hosts on the LAN segment to maintain access to the Web router if a single point of
failure occurs.