1-9The VRRP load balancing mode is based on the VRRP standard protocol mode, so mechanisms, suchas master election, preemption, and tracking functions, in the standard protocol mode are alsosupported in the load balancing mode. Besides, VRRP load balancing mode has some newmechanisms, which are introduced in the following parts.Allocating Virtual MAC AddressesWhen VRRP works in the load balancing mode, the master allocates virtual MAC addresses to routersin the VRRP group and replies the ARP requests (for the IPv4 network) or ND requests (for the IPv6network) from different hosts by allocating different virtual MAC addresses to the hosts. The backuprouters, however, do not reply the ARP requests (for the IPv4 network) or ND requests (for the IPv6network) from the hosts.Figure 1-7 Allocating virtual MAC addressesAs shown in Figure 1-7, 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 allocates different virtual MAC addresses to RoutersA, B and C.Host A, Host B, and Host C send ARP requests to obtain the MAC address corresponding to thegateway with the virtual IP address 10.1.1.1. The master (Router A) replies ARP requests of the hostswith different virtual MAC addresses.z The MAC address obtained by Host A is the virtual MAC address of Router A, that is, Host A takesthe virtual MAC address of Router A as the MAC address of the gateway, and thus to ensure thatthe packets from Host A are forwarded by Router A.
