Vrrp Standby Group Overview - H3C S3610-28P Operation Manual

Operation Manual – VRRP
H3C S3610&S5510 Series Ethernet Switches
Host A
Host B
Host C
Figure 1-1 LAN networking
Apparently, this approach to enabling hosts on a network to communicate with external
networks is easy to configure but it imposes a very high requirement of performance
stability on the device acting as the gateway. A common way to improve system
reliability is to use more egress gateways, introducing the problem of routing among the
multiple egresses.
Virtual Router Redundancy Protocol (VRRP) is an error-tolerant protocol designed to
address this problem through separating physical devices from logical devices.
Deploying VRRP on multicast and broadcast LANs such as Ethernet, you can ensure
that the system can still provide highly reliable default links without changing
configurations (such as dynamic routing protocols, route discovery protocols) when a
device fails and prevent network interruption due to a single link failure.
There are two VRRP versions: VRRPv2 and VRRPv3. VRRPv2 is based on IPv4, while
VRRPv3 is based on IPv6. The two versions implement the same functions but provide
different commands.

1.1.2 VRRP Standby Group Overview

VRRP combines a group of switches (including a master and multiple backups) on a
LAN into a virtual router called standby group.
The VRRP standby group has the following features:
A virtual router has an IP address. A host on the LAN only needs to know the IP
address of the virtual router and uses the IP address as the next hop of the default
route.
Every host on the LAN communicates with external networks through the virtual
router.
Switches in the standby group elect the gateway according to their priorities. Once
the master switch acting as the gateway fails, the other switches in the standby
Network
Gateway
1-2
Chapter 1 VRRP Configuration