
123
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
, 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.
Figure 35
Allocating virtual MAC addresses
2.
Upon receiving an ARP request destined for the virtual IP address of the VRRP group from a host,
the master, based on the load balancing algorithm, uses a corresponding virtual MAC address to
answer the ARP request. For example, as shown
, when Host A sends an ARP request to
retrieve the MAC address of gateway 10.1.1.1, the master—Router A, after receiving the request,
returns the virtual MAC address of Router A to Host A; when Host B sends an ARP request to
retrieve the MAC address of gateway 10.1.1.1, the master, after receiving the request, returns the
virtual MAC address of Router B to Host B.