Vrrp Timers - H3C S5500-EI Series Operation Manual

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches
remains 255. That is, if there is an IP address owner in a standby group, it acts as the
master as long as it works properly.
II. Working mode
A switch in a standby group can work in one of the following two modes:
Non-preemption mode
Once a switch in the standby group becomes the master, it stays as the master as long
as it operates normally, even if a backup switch is assigned a higher priority later.
Preemption mode
Once a backup switch finds its priority higher than that of the switch acting as the
master, it sends VRRP advertisements to start a new master switch election in the
standby group and becomes the master. Accordingly, the original master switch
becomes a backup.
III. Authentication mode
VRRP provides two authentication modes:
simple: Simple text authentication
You can adopt the simple text authentication mode in a network facing possible security
problems. A switch sending a packet fills the authentication key into the packet, and the
switch receiving the packet compares its local authentication key with that of the
received packet. If the two authentication keys are the same, the received VRRP
packet is considered real and valid; otherwise, the received packet is considered an
invalid one.
md5: MD5 authentication
You can adopt MD5 authentication in a network facing severe security problems. The
switch encrypts a packet to be sent using the authentication key and MD5 algorithm
and saves the encrypted packet in the authentication header. The switch receiving the
packet uses the authentication key to decrypt the packet and checks whether the
packet is valid.
On a secure network, you need not set the authentication mode.

1.1.3 VRRP Timers

VRRP timers include VRRP advertisement interval timer and VRRP preemption delay
timer.
I. VRRP advertisement interval timer
The master switch in a VRRP standby group sends VRRP advertisements periodically
to inform the other switches in the standby group that it operates properly.
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Chapter 1 VRRP Configuration