VRRP Introduction
©2008 Allied Telesis Inc. All rights reserved.
Software Version 5.2.1
AlliedWare Plus
TM
Operating System Software Reference C613-50003-00 REV E
46.5
To disable the router and retain the configuration
VRRP Election and Pre-empt
If the switch that is the current VRRP master becomes unavailable, the master role is taken by
the switch with the next highest priority. The priority is a value from 1 to 255, with a default of
100. The value 255 is reserved for the switch that owns the virtual router’s IP address. The new
master takes over all the responsibilities of the original master.
By default, when a switch becomes available that has a higher priority than the master, this
switch takes over as master. This is referred to as
pree
m
pt
m
ode
and can be set
on
or
off
. Even
with preempt mode
off
, the switch that owns the IP address always becomes the master when
available. If two switches are configured with the same priority, the one with the highest IP
address has higher priority. Preempt mode must be the same for all switches in the virtual
router.
Hosts on the LAN can continue sending packets to the virtual MAC address they originally
associated with the first hop IP address, even though the switch that owns the IP address is not
currently available. When the original switch becomes available again, and if it is a preferred
switch (i.e. it owns the virtual router IP address) then it resumes the role of master.
Use the following commands to set the priority and preempt mode when you create the virtual
router:
To set the priority and preempt mode for VRRP 1
The advertisement interval determines the rate that the master sends its advertisement
packets. This rate must be the same value for all switches in the virtual router. The default
advertisement interval of 1second can be used for most networks. However, you can modify
this interval by using
advertisement-interval
command, as shown in the following procedure:
To set the advertisement interval to 5 seconds on VRRP1
awplus#
configure terminal
Enter the privileged exec mode.
awplus(config)#
router vrrp 1
Select the VRRP session on the switch.
awplus(config-router)#
disable
Disable the VRRP session on the
switch
awplus(config-router)#
CNTL/Z
Return to the
config
prompt
plus#
configure terminal
Enter the privileged exec mode.
awplus(config#
) router vrrp 1
Select the VRRP session on the switch.
awplus(config-router)#
priority 255
Set the VRRP priority for the switch
awplus(config-router)#
preempt true
Select the preempt mode for the
VRRP 1.
awplus(config-router)#
enable
Enable the VRRP session on the switch
awplus(config-router)#
CNTL/Z
Return to the
config
prompt
plus#
configure terminal
Enter the privileged exec mode.
awplus(config#
router vrrp 1
Select the VRRP session on the switch.
awplus(config-router)#
advertisement-
interval 5
Set the advertisement interval.