1080 CHAPTER 87: VRRP CONFIGURATION
master. The new master takes over the forwarding task to provide services to hosts
on the LAN.
Load balancing
You can create more than one standby group on an interface of a switch, allowing
the switch to be the master of one standby group but a backup of another at the
same time.
In load balancing mode, multiple switches provide services at the same time. This
mode requires two or more standby groups, each of which includes a master and
one or more backups. The masters of the standby groups can be assumed by
different switches, as shown in Figure 323.
Figure 323 VRRP in load balancing mode
A switch can be in multiple standby groups and hold a different priority in
different group.
In Figure 323, three standby groups are present:
■ Standby group 1: Switch A is the master; Switch B and Switch C are the
backups.
■ Standby group 2: Switch B is the master; Switch A and Switch C are the
backups.
■ Standby group 3: Switch C is the master; Switch A and Switch B are the
backups.
For load balancing among Switch A, Switch B, and Switch C, hosts on the LAN
need to be configured to use standby group 1, 2, and 3 as the default gateways
respectively. When configuring VRRP priorities, ensure that each switch holds such
a priority in each standby group that it will take the expected role in the group.
Host A
Host B
Host C
Switch A
Backup
Switch B
Backup
Switch C
Master
Virtual router 2
Virtual router 3Virtual router 1
Master
Backup
Backup Backup
Master
Backup
Network
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