3Com 7750 Series Command Reference Manual page 703

3Com Switch 7750 Series
Command Reference Guide – VRRP & HA
View
VLAN interface view
Parameter
virtual-router-id: VRRP backup group ID ranging from 1 to 255.
delay-value: Delay period (in seconds) ranging from 0 to 255.
Description
Use the vrrp vrid preempt-mode command to configure a switch to operate in the
preemptive mode and set the delay period.
Use the undo vrrp vrid preempt-mode command to cancel the configuration.
By default, switches in a backup group operate in the preemptive mode, with the delay
period set to 0 seconds.
If you want backup switches to preempt the master switch, configure them to operate in
the preemptive mode. You can also set the delay period for preemption as needed.
As long as a switch in the backup group becomes the master switch, other switches,
even if they are configured with a higher priority later, do not preempt the master switch
unless they operate in preemptive mode. The switch operating in preemptive mode will
become the master switch when it finds its priority is higher than that of the current
master switch, and the former master switch becomes a backup switch accordingly.
You can configure an Switch 7750 series switch to operate in preemptive mode. You
can also set the delay period. A backup switch waits for a period of time (the delay
period) before becoming a master switch. Setting a delay period aims at:
In an unstable network, backup switches in a backup group possibly cannot receive
packets from the master in time due to network congestions even if the master operates
properly. This causes the master of the backup group being determined frequently.
With the configuration of delay period, the backup switch will wait for a while if it does
not receive packets from the master switch in time. A new master is determined only
after the backup switches do not receive packets from the master switch after the
specified delay time.
Note:
You can use the undo vrrp vrid preempt-mode command to set switches in a backup
group to operate in non-preemptive mode.
Example
# Configure the switches to operate in the preemptive mode.
Chapter 1 VRRP Configuration Commands
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