Principles Of Vrrp; Vrrp Interface Tracking; Vrrp Application (Taking Ipv4-Based Vrrp For Example) - H3C S7500E Series Operation Manual

Operation Manual – HA
H3C S7500E Series Ethernet Switches
Authentication Data: Authentication key. Currently, this field is used only for simple
authentication and is 0 for any other authentication modes.

1.1.5 Principles of VRRP

With VRRP enabled, the switches determine their respective roles in the standby
group by priority. The switch with the highest priority becomes the master, while
the others are the backups. The master sends VRRP advertisement packets
periodically to notify the backups that it is working properly, and each of the
backups starts a timer to wait for advertisement packets from the master.
In preemption mode, when a backup receives a VRRP advertisement packet, it
compares the priority in the packet with that of its own. If its priority is higher, it
becomes the master; otherwise, it remains a backup.
In non-preemption mode, the switch in the standby group remains as a master or
backup as long as the master does not fail. The backup will no become the master
even if the former is configured with a higher priority.
If the timer of a backup expires but the backup still does not receive any VRRP
advertisement packet, it considers that the master fails. In this case, the backup
switch considers itself as the master switch and sends VRRP advertisements to
start the election process to elect a new master switch for forwarding packets.

1.1.6 VRRP Interface Tracking

The interface tracking function expands the backup functionality of VRRP. It provides
backup not only when the interface to which a standby group is assigned fails but also
when other interfaces on the switch become unavailable. This is achieved by tracking
interfaces. When a monitored interface goes down, the priority of the switch owning the
interface is automatically decreased by a specified value, allowing a higher priority
switch in the standby group to become the master.

1.1.7 VRRP Application (Taking IPv4-Based VRRP for Example)

I. Master/backup
In master/backup mode, only one switch, the master, provides services. When the
master fails, a new master is elected from the original backups. This mode requires
only one standby group, in which each switch holds different priorities and the one with
the highest priority becomes the master, as shown in Figure
1-7
Chapter 1 VRRP Configuration
1-5.