H3C Technologies H3C SR8800 - Manual (Page 57)

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• 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.
For load sharing among Router A, Router B, and Router C, hosts on the LAN need to be configured to use
VRRP group 1, 2, and 3 as the default gateways respectively. When you configure 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 standard protocol mode, only the master can forward packets and the backups are
in the state of listening. You can create multiple VRRP groups to share the load among multiple routers,
but hosts on the LAN need to be configured with different gateways, thus making the configuration
complicated.
In load balancing mode, VRRP provides load balancing in addition to virtual gateway redundancy by
mapping a virtual IP address to multiple virtual MAC addresses to assign each router in a VRRP group
one virtual MAC address. In this way, each router in this VRRP group can respond to ARP requests (in an
IPv4 network) or ND requests (in an IPv6 network) from corresponding hosts, so that different hosts can
send packets to different routers, and each router in the VRRP group can forward packets. In load
balancing mode, you need to create only one VRRP group to balance load among multiple routers,
instead of allowing one router to bear the load but other routers to stay idle.
NOTE:
VRRP load balancing mode is based on VRRP standard protocol mode, so mechanisms, such as master
election, preemption, and tracking functions, in the standard protocol mode are also supported in the load
balancing mode. In addition, VRRP load balancing mode has new mechanisms, which are introduced in
the following sections.
Assigning virtual MAC addresses
When VRRP works in load balancing mode, the master assigns virtual MAC addresses to the routers in
the VRRP group and answers the ARP requests or ND requests from different hosts. The backup routers,
however, do not answer the ARP requests or ND requests from the hosts.
Assume that a VRRP group works in an IPv4 network. The following describes how the load balancing
mode works:
1. The master assigns virtual MAC addresses to the routers (including the master itself and the
backups) in the VRRP group. For example, as shown in
Figure 16 , the virtual IP address of the VRRP
group is 10.1.1.1/24; Router A is the master; Router B and Router C are the backups. Router A
assigns 000f-e2ff-0011 to itself, and 000f-e2ff-0012 to Router B.