Vrrp Application (Using Ipv4-Based Vrrp For Example) - H3C S9500E Series Configuration Manual

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Monitor an uplink and modify the priority of the router according to the state of the uplink. If
there is a fault on the uplink, hosts in the LAN cannot access the external network through
the router. In this case, the state of the monitored track entry changes to negative and the
priority of the router decreases by a specified value. After that, a higher priority router in the
VRRP group becomes the master to maintain the proper communication between the hosts in
the LAN and the external network.
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Monitor the master on a backup. If there is a fault on the master, the backup working in the
mode switches to the master immediately to maintain normal communication.
For more information about the track entry, see Track in the High Availability Configuration Guide.

VRRP application (using IPv4-based VRRP for example)

Master/backup
In master/backup mode, only one router, the master, forwards packets. When the master fails, a
new master is elected from the original backups. This mode requires only one VRRP group, in
which each router holds a different priority and the one with the highest priority becomes the
master, as shown in Figure 26.
Figure 26 VRRP in master/backup mode
At the beginning, Router A is the master and therefore can forward packets to external networks.
Router B and Router C are backups, and therefore are in the state of listening. If Router A fails,
Router B and Router C elect a new master. The new master takes over the forwarding task to
provide services to hosts on the LAN.
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