Allocating Virtual Mac Addresses - H3C S9500E Series Configuration Manual

load sharing among multiple routers, hosts on the LAN need to be configured with different
gateways, making the configuration complicated.
For load balancing, besides virtual gateway redundancy, VRRP can work in load balancing
mode. In load balancing mode, you associate a virtual IP address with multiple virtual MAC
addresses to make each router in a VRRP group correspond to a virtual MAC address. This allows
each router in the VRRP group to forward packets. In load balancing mode, you can create just
one VRRP group for load balancing among multiple routers, which avoids keeping the backups
always in the idle state and not fully utilizing network resources.
VRRP load balancing mode is based on VRRP standard protocol mode, so mechanisms such as master
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election, preemption, and tracking functions in standard protocol mode are also supported in load
balancing mode. Additionally, VRRP load balancing mode also has other mechanisms, which are
described below.
To configure the VRRP load balancing function in IRF mode, you must configure the bridge MAC address
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to be permanently preserved (default setting). For more information about IRF mode, see IRF in the IRF
Configuration Guide.

Allocating virtual MAC addresses

When VRRP works in load balancing mode, the master allocates virtual MAC addresses to routers
in the VRRP group and replies to ARP requests (for the IPv4 network) or ND requests (for the IPv6
network) from different hosts by allocating different virtual MAC addresses to the hosts according
to a load balancing algorithm. The backup routers, however, do not reply to ARP requests (for the
IPv4 network) or ND requests (for the IPv6 network) from the hosts.
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