HSRP Explained: Gateway Redundancy Made Simple
HSRP (Hot Standby Router Protocol) gives a network a redundant default gateway. Two or more routers share one virtual IP; one is Active and forwards traffic, another is Standby, ready to take over in seconds if the Active fails — so hosts never lose their gateway.
Active, standby, priority and preemption
Routers elect an Active based on highest priority (default 100; ties broken by highest IP). The Standby monitors the Active via hellos and takes over on failure. By default HSRP does not preempt — a recovered higher-priority router won't reclaim the Active role unless you enable standby preempt. This is a classic exam gotcha.
HSRP vs VRRP vs GLBP
HSRP and GLBP are Cisco-proprietary; VRRP is the open standard. GLBP adds active-active load balancing across multiple gateways, while HSRP/VRRP use one active router at a time. These first-hop redundancy protocols (FHRPs) are core CCNP infrastructure topics.
Frequently asked questions
What does HSRP do?
HSRP provides a redundant default gateway: multiple routers share a virtual IP, with one active and others on standby to take over automatically on failure.
What is HSRP preemption?
A setting that lets a higher-priority router reclaim the Active role after recovering. It's off by default, so the current Active keeps the role unless preempt is configured.
What is the difference between HSRP and VRRP?
HSRP is Cisco-proprietary; VRRP is an open IETF standard. Both provide gateway redundancy with one active router; GLBP additionally load-balances.
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