R3204P16-HP Load Balancing Module High Availability Configuration Guide-6PW101

In Figure 5, three VRRP groups are present:

• VRRP group 1—Router A is the master; Router B and Router C are the backups.

• VRRP group 2—Router B is the master; Router A and Router C are the backups.

• VRRP group 3—Router C is the master; Router A and Router B are the backups.

To balance load among Router A, Router B, and Router C, configure hosts on the LAN to use VRRP group

1, 2, and 3 as the default gateways respectively. When configuring VRRP priorities, make sure that each

router holds such a priority in each VRRP group that it will take the expected role in the group.

VRRP load balancing mode

Overview

When VRRP works in the standard protocol mode, only the master can forward packets and the backups

are in the state of listening. Although you can create multiple VRRP groups to implement load sharing

among multiple routers, hosts on the LAN need to be configured with different gateways, thus making the

configuration complicated.

When VRRP works in the load balancing mode, namely, besides virtual gateway redundancy, VRRP

realizes load balancing. The working principle is as follows: associate a virtual IP address with multiple

virtual MAC addresses to make each router in a VRRP group correspond to a virtual MAC address. In this

way, each router in this VRRP group can forward packets. In the load balancing mode, you need to

create only one VRRP group to realize load balancing among multiple routers, thus avoiding that the

backups are always in the idle state and the network resources are not fully utilized.

NOTE:

The VRRP load balancin

mode is based on the VRRP standard protocol mode, so mechanisms, such as

master election, preemption, and trackin

functions, in the standard protocol mode are also supported in

the load balancing mode. Besides, VRRP load balancing mode has some new mechanisms, which are

introduced in the following parts.

Allocating virtual MAC addresses

When VRRP works in the load balancing mode, the master allocates virtual MAC addresses to routers in

the VRRP group and replies the ARP requests from different hosts by allocating different virtual MAC

addresses to the hosts. The backup routers, however, do not reply the ARP requests from the hosts.