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DES-7200 Configuration Guide Chapter 2 VRRP Plus Configuration
2-2
BVG is responsible for distributing virtual MAC addresses to BVFs. In order to
be compatible with VRRP, BVG directly uses the virtual MAC address of
VRRP, namely 00-00-5E-00-01-{VRID} (VRID is the ID of VRRP group). BVF
uses the virtual MAC address of 00-1A-A9-16-{MemberID}-{VRID}. MemberID
is the ID of VRRP Plus member. Currently, VRRP Plus can support four
members. BVG uses the member ID of 01, while other three BVF members
use ID 02-04.
BVG responds to the ARP requests sent by hosts in the LAN. Depending on
different balancing policies, BVG will reply with different virtual MAC
addresses. There are three balancing policies: host-dependent, round-robin
and weighted. The host-dependent policy indicates that BVG will reply with
specific virtual MAC address to the specific host; the round-robin policy
indicates that BVG will respond to the ARP requests with the virtual MAC
addresses in the backup group by rotation; the weighted policy indicates that
BVG will respond to ARP requests according to the forwarding capacity of the
device.
VRRP Plus also provides the feature of redundant backup. BVG can utilize
VRRP-BFD session information to establish session with BVF, so as to detect
the active state of BVF within milliseconds. If BVF fails, BVG will arrange one
of the remaining members to take over the forwarding function of the failed
BVF. This feature is called proxy forwarding. If BVF recovers from the fault,
then it will restore its forwarder role and continue to forward packets of this
virtual MAC address. However, if such device doesn't recover, then the
backup group shall stop redirecting traffic to this virtual MAC address, namely
further ARP requests will no longer be replied with this virtual MAC address.
Moreover, after a long-enough time, we can assume that users using this
virtual MAC address as the gateway MAC address have already updated ARP
entry of gateway address, with traffic being handled by other devices. By this
time, we can delete this virtual MAC address, and packets sent to this virtual
MAC address shall be dropped. For this reason, VRRP Plus supports the
configuration of redirect and timeout timers of the backup group. When the
device fails, the backup group will assign the virtual MAC address to other
device for proxy forwarding. Within the redirect time, the backup group will
continue to reply to ARP requests with this virtual MAC address; after the
redirect timer runs out, it will no longer reply with this virtual MAC address.
Upon expiration of the timeout timer, the backup group will delete this virtual
MAC address.
VRRP Plus supports weighting configuration of the backup group. By
configuring different weights for difference devices, those with larger weights
will share more traffic and those with smaller weights will share less traffic, so
that the forwarding capacity of difference devices can be fully utilized. When
the weighting value of BVF device in the backup group is below the lower