Vrrp Load Balancing Mode; Virtual Mac Address Assignment - HP 6125XLG Configuration Manual

VRRP group 1—Router A is the master. Router B and Router C are the backups.
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• 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.
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To implement load sharing among Router A, Router B, and Router C, hosts on the subnet must be
configured with the virtual IP addresses of VRRP group 1, 2, and 3 as default gateways, respectively.
When you configure them, make sure that each router is assigned an appropriate priority in each VRRP
group so that each router can take the expected role in each group.

VRRP load balancing mode

In a standard-mode VRRP group, only the master can forward packets and backups are in listening state.
You can create multiple VRRP groups to share traffic, but you must configure different gateways for hosts
on the subnet.
In load balancing mode, a VRRP group maps its virtual IP address to multiple virtual MAC addresses,
assigning one virtual MAC address to each member router. Every router in this VRRP group can forward
traffic and respond to IPv4 ARP requests or IPv6 ND requests from hosts. Because their virtual MAC
addresses are different, traffic from hosts is distributed across the VRRP group members. Load balancing
mode simplifies configuration and improves forwarding efficiency.
VRRP load balancing mode uses the same master election, preemption, and tracking mechanisms as the
standard mode, and adds new mechanisms as described in the following sections.

Virtual MAC address assignment

In load balancing mode, the master assigns virtual MAC addresses to routers in the VRRP group and uses
different MAC addresses to respond to ARP requests or ND requests from different hosts. The backup
routers, however, do not answer ARP requests or ND requests from hosts.
In an IPv4 network, a load balanced VRRP group works as follows:
1. The master assigns virtual MAC addresses to all member routers, including itself. This example
assumes that the virtual IP address of the VRRP group is 10.1.1.1/24, Router A is the master, and
Router B is the backup. Router A assigns 000f-e2ff-0011 for itself and 000f-e2ff-0012 for Router
B. See Figure 16.
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