Chapter 30 Configuring Hsrp; Understanding Hsrp - Cisco 3845 - Security Bundle Router Software Manual

Configuring HSRP
This chapter describes how to use Hot Standby Router Protocol (HSRP) on the Cisco ME 3800X and
ME 3600X switch to provide routing redundancy for routing IP traffic without being dependent on the
availability of any single router.
For complete syntax and usage information for the commands used in this chapter, see the switch
Note
command reference for this release and the Cisco IOS IP Command Reference, Volume 1 of 3:
Addressing and Services, Release 12.2.
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Understanding HSRP

HSRP is Cisco's standard method of providing high network availability by providing first-hop
redundancy for IP hosts on an IEEE 802 LAN configured with a default gateway IP address. HSRP routes
IP traffic without relying on the availability of any single router. It enables a set of router interfaces to
work together to present the appearance of a single virtual router or default gateway to the hosts on a
LAN. When HSRP is configured on a network or segment, it provides a virtual Media Access Control
(MAC) address and an IP address that is shared among a group of configured routers. HSRP allows two
or more HSRP-configured routers to use the MAC address and IP network address of a virtual router.
The virtual router does not exist; it represents the common target for routers that are configured to
provide backup to each other. One of the routers is selected to be the active router and another to be the
standby router, which assumes control of the group MAC address and IP address should the designated
active router fail.
Routers in an HSRP group can be any router interface that supports HSRP, including routed ports and
Note
switch virtual interfaces (SVIs) on the switch.
HSRP provides high network availability by providing redundancy for IP traffic from hosts on networks.
In a group of router interfaces, the active router is the router of choice for routing packets; the standby
router is the router that takes over the routing duties when an active router fails or when preset conditions
are met.
OL-23400-01
Understanding HSRP, page 30-1
Configuring HSRP, page 30-5
Displaying HSRP Configurations, page 30-11
C H A P T E R
Cisco ME 3800X and 3600X Switch Software Configuration Guide
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