Chapter 1 Route Redundancy Backup; Vrrp Overview; Stand-Alone Default Route; Introduction To Vrrp - H3C SecPath F1800-A Operation Manual

Operation Manual - Reliability
H3C SecPath F1800-A Firewall

Chapter 1 Route Redundancy Backup

1.1 VRRP Overview

1.1.1 Stand-alone Default Route

Usually, each host on an internal network is configured with a default route to the next
hop, which is the IP address of the egress router; that is, 10.100.10.1, as shown in
Figure 1-1.
Each host on the internal network that wants to access external networks will send
packets to the egress Router A, which forwards these packets; in this way, internal
hosts can communicate with external networks.
Serv
Server
er
Internal network
10.100.10.0/24
Figure 1-1 Networking of adopting default route
In the default route mode, there is only one router at the egress of the internal network.
When Router A fails, all hosts, whose default next hop is Router A, on the internal
network will fail to communicate with external networks. So communication is
unreliable in the default route mode.

1.1.2 Introduction to VRRP

Virtual Router Redundancy Protocol (VRRP) can solve such a problem.
As a kind of fault tolerant protocol, VRRP applies to such a LAN that supports
multicast or broadcast, such as Ethernet. It organizes several routers on an LAN
together into a virtual router, which is named a backup group. In a backup group, only
one device is in active state, which is named Master; others are in monitoring state
10.100.10.1
P
PC
C
RouterA
Chapter 1 Route Redundancy Backup
Inter
Internet
net
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