H3C Technologies H3C S6800 Series Switches - Manual (Page 29)

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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, and preemption 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 11 .
Figure 11 Virtual MAC address assignment
2. When an ARP request arrives, the master (Router A) selects a virtual MAC address based on the
load balancing algorithm to answer the ARP request. In this example, Router A returns the virtual
MAC address of itself in response to the ARP request from Host A, and returns the virtual MAC
address of Router B in response to the ARP request from Host B. See Figure 12 .
Gateway IP: 10.1.1.1/24 Gateway IP: 10.1.1.1/24
Virtual MAC: 000f-e2ff-0012
Host A Host B
Router A
Master
Router B
Backup
Virtual IP: 10.1.1.1/24
Network
Virtual MAC: 000f-e2ff-0011
Allocate Virtual MAC
000f-e2ff-0012 to Router B