The MIB module provides a means to monitor and configure
the Cisco IOS proprietary Hot Standby Router Protocol
(HSRP). Cisco HSRP protocol is defined in RFC2281.

Terminology:

HSRP is a protocol used amoung a group of routers for the
purpose of selecting an 'active router' and a 'standby
router'.

An 'active router' is the router of choice for routing
packets.

A 'standby router' is a router that takes over the routing
duties when an active router fails, or when preset
conditions have been met.

An 'HSRP group' or a 'standby group' is a set of routers
which communicate using HSRP. An HSRP group has a group MAC
address and a group Virtual IP address. These are the
designated addresses. The active router assumes (i.e.
inherits) these group addresses.

'Hello' messages are sent to indicate that a router is
running and is capable of becoming the active or standby
router.

'Hellotime' is the interval between successive HSRP Hello
messages from a given router.

'Holdtime' is the interval between the receipt of a Hello
message and the presumption that the sending router has
failed.