Vrrp Overview; Introduction - Huawei NetEngine80E Configuration Manual - Reliability

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability

4.1 VRRP Overview

A Virtual Router Redundancy Protocol (VRRP) backup group consists of a master device and
one or more backup devices. A backup device can take over traffic from the master device if the
master device fails, improving network reliability.

4.1.1 Introduction

VRRP is a fault-tolerant protocol running on routers. These routers provide a single default
gateway address for hosts. If a VRRP-enabled router fails, another VRRP-enabled router takes
over traffic, ensuring continuity and reliability for network communication.
VRRP Introduction
As networks rapidly develop and applications become diversified, various value-added services
such as IPTV and video conferencing are widely used. Any network service interruption will
result in immeasurable loss to users. Demands for network infrastructure reliability are
increasing, especially in non-stopping network transmission for users.
Hosts on a LAN are usually connected to an external network through a default gateway. When
the hosts send packets destined for addresses out of the local network segment, these packets
will follow a default route to an egress gateway. The egress gateway is Router A shown in
4-1. Router A forwards these packets to the external network so that the hosts can communicate
with the external network.
Figure 4-1 Default gateway on a LAN
IP Address:10.0.0.2/24
IP Address:10.0.0.3/24
IP Address:10.0.0.4/24
If Router A fails, hosts connected to it cannot communicate with the external network. This
communication failure persists even if another router is added to the LAN. Only one default
gateway (router) can be configured for most hosts on a LAN and used to forward all data packets
destined for devices that are not on the local network segment. Hosts send packets only through
the default gateway even if multiple routers are connected to the hosts.
One method to prevent communication interruption is usually to configure multiple egress
gateways but this method is only available if one of routes to these egress gateways can be
selected. Another method is to use dynamic routing protocols, such as the Routing Information
Protocol (RIP), Open Shortest Path First (OSPF) protocol, or Internet Control Message Protocol
Issue 02 (2014-09-30)
Gateway:10.0.0.1
Gateway:10.0.0.1
Gateway:10.0.0.1
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10.0.0.1/24
RouterA
Ethernet
4 VRRP Configuration
Network
Figure
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