HSRP defines six states in which an
HSRP-enabled router can exist. The HSRP states are listed in the
figure.
- Initial - This is the state from
which the routers begin the HSRP process; this state indicates that
HSRP is not running. It is entered via a configuration change or
when an interface first comes up.
- Learn - The router has not
determined the virtual IP address, and has not yet seen an
authenticated hello message from the active router. In this state
the router is still waiting to hear from the active router.
- Listen - The router knows the
virtual IP address, but is neither the active router nor the standby
router. It listens for hello messages from those routers. Routers
other than the active and standby router remain in the listen state.
- Speak - The router sends periodic
hello messages and is actively participating in the election of the
active or standby router. A router cannot enter Speak state unless
it has the virtual IP address.
- Standby - The router is a
candidate to become the next active router and sends periodic hello
messages. Excluding transient conditions, there must be at most one
router in the group in Standby state.
- Active - The router is currently
forwarding packets that are sent to the group virtual MAC address.
The router sends periodic hello messages. Excluding transient
conditions, there must be at most one router in Active state in the
HSRP group.
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