HackMDFirst-Hop Redundancy Protocols
Hot-Standby Redudancy Protocol
HSRP is a Cisco-proprietary FHRP that is designed to allow for transparent failover of a first-hop IP device.
HSRP Priority
HSRP priority can be used to determine the active router. The router with the highest HSRP priority will become the active router. By default, the HSRP priority is 100. If the priorities are equal, the router with the numerically highest IPv4 address is elected as the active router.
To configure a router to be the active router, use the standby priority <0-255> interface command.
HSRP Preemption
By default, after a router becomes the active router, it will remain the active router even if another router comes online with a higher HSRP priority.
To force a new HSRP election process to take place when a higher priority router comes online (or comes back online), preemption must be enabled using the standby preempt interface command.
Preemption only allows a router to become the active router if it has a higher priority.
With preemption disabled, the router that boots up first will become the active router if there are no other routers online during the election process.
