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DES-7200 Configuration Guide Chapter 2 VRRP Plus Configuration
2-1
2 VRRP Plus Configuration
2.1 Overview
VRRP Plus (Virtual Router Redundancy Protocol Plus) is the extension to
VRRP protocol. It utilizes VRRP protocol to perform gateway backup and load
balancing in an IEEE 802.3 LAN.
One drawback of VRRP is that the backup router doesn't participate in packet
forwarding. To achieve load balancing by utilizing VRRP, we need to manually
configure multiple VRRP groups, and point the gateway of LAN hosts to the
virtual IP of different VRRP groups. This will increase the workload of network
administrator. VRRP Plus is introduced to address the aforementioned
drawback.
The benefit of VRRP Plus is automatic load balancing. It will automatically
distribute the traffic from different hosts to VRRP Plus members, thus
substantially easing the load of network administrator.
2.2 Working Principle
Basic principle of VRRP Plus: Hosts in the LAN use the same gateway IP.
When different hosts send ARP requests to the gateway, VRRP Plus will reply
with different virtual MAC addresses, thus distributing the traffic from different
hosts to different VRRP Plus members and allowing load balancing.
VRRP Plus has introduced two roles:
BVG: Balancing Virtual Gateway, which is responsible for distributing virtual
MAC addresses among VRRP Plus members, replying to gateway ARP
requests and forwarding packets sent by hosts in the LAN.
BVF: Balancing Virtual Forwarder, which is responsible for forwarding packets
sent by hosts in the LAN.
VRRP Plus is independent from the VRRP protocol and features the following
rules:
The Master role in VRRP corresponds to the BVG role in VRRP Plus; the
Backup role in VRRP corresponds to the BVF role in VRRP Plus. The
gateway of LAN hosts still points the same virtual IP as mentioned in VRRP.