Huawei v200r001 user manual Configuration of Hsrp, Hsrp Overview

User Manual - Configuration Guide (Volume 3)	Chapter 2
Versatile Routing Platform	Configuration of HSRP

Chapter 2 Configuration of HSRP

2.1 HSRP Overview

HSRP (Hot Standby Router Protocol), is a reliability protocol based on hot standby mechanism. It aims, when using a router as the gateway, to enhance the connection reliability between the network and the outside through hot standby mechanism. It will be suffice to configure HSRP on a router, which does not affect the local host and there is no need to make configuration on the local host.

Put two or more routers into a hot standby group to implement HSRP: from the local host’s point of view, this hot standby group is a virtual router itself, with its own IP address (a virtual IP address), and the local hosts use this virtual router as a gateway.

In the hot standby group, there is one active Router. It does the work of a virtual router such as forwarding the local host’s data and messages to the virtual router. And there is a router in the standby state that is ready to switch over to the active state at any time when it is necessary. The other routers (if any) in the group are in a listen state. The state of non-active routers (standby or listen) are determined by their own priority, i.e., the router with the highest priority will be in standby state, which leaves the other routers to be in a listen state. If they have the same priority, then the one with a bigger Ethernet interface IP address will be in a standby state, leaving the rest ones to be in a listen state.

When fault occurs, a standby router will take over the work of the active router, and one of the rest routers (if any) with the highest priority will be selected as the standby router. Thus, the local host can keep using this virtual router gateway without any modifications.

IP address: 202.38.160.1

Router A (Active)

Workstation

Virtual IP address: 202.38.160.10

Gateway IP address:

Ethernet

Virtual MAC address: 00-E0-FC-00-5F-01

202.38.160.10

Virtual router

Router B (Standby)

IP address: 202.38.160.2

Figure LC-2-1Schematic diagram of HSRP application

In this figure, Router A and Router B form a hot standby group, which has the following workflow:

A certain local host takes the IP address 202.38.160.10 of the hot standby group— virtual router as its own gateway address. Before transmitting messages through gateway, it sends out an ARP request in the hope of obtaining a virtual MAC address

2-1