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Chapter 8

Hot Standby Routing Protocol (HSRP)

then a standby router inherits both the lead position and the Hot Standby
group address.

HSRP defines six states in which an HSRP router may run:

Initial All routers begin in this state when configured with HSRP. HSRP
is not running on the router yet because the interface configured with
HSRP is not up and active yet.

Learn The router is in the learn state when it has not heard from the
active router. It does not know the active router and does not know the IP
address of the virtual router

Listen The router enters the listen state after it hears from the active
router and knows the IP virtual address. This router is not the active or
standby router.

Speak After a router learns the IP address of the virtual router, the
router will enter the speak state. It will actively participate in the election
of the active and standby router. It sends hello messages to the active
router.

Standby This state means the router will become the active router if the
active router fails. There must one active router in the HSRP group.

Active This state tells the router to forward packets, which are sent to
the virtual IP address. There must be one active router in the HSRP group.

Configuring HSRP

Configuring HSRP is pretty simple. We'll show you more difficult configu-
rations of HSRP that you can use in larger internetworks later in this chap-
ter. But for now, let's consider the simple example shown in Figure 8.3. Here
there is a virtual router with the IP address of 10.1.0.200. All clients on that
Ethernet segment configure that IP address as their default gateway.

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