Specifications

Chapter 5. IBM System Networking RackSwitch implementation 225
d. Define the election priority (Example 5-70).
Run virtual-router <1-15> priority <1-254> to define the election priority bias for
this virtual server. The priority value can be any integer 1 - 254. The default value
is 100.
During the master router election process, the routing device with the highest virtual
router priority number wins. If there is a tie, the device with the highest IP interface
address wins. If this virtual router’s IP address is the same as the one used by the IP
interface, the priority for this virtual router is automatically set to 255 (highest).
When priority tracking is used, this base priority value can be modified according to a
number of performance and operational criteria.
In our reference architecture, we used a different Virtual router IP address from the IP
interface addresses and assigned a higher priority to ACC-1 switch, in order for it to
become an elected master. The ACC-2 switch is left as its default priority (100)
(Example 5-70).
Example 5-70 Virtual router election priority configuration
ACC-1#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-1(config)#router vrrp
ACC-1(config-vrrp)#virtual-router 1 priority 105
ACC-1(config-vrrp)#
e. Configure preemption (Example 5-71).
Run [no] virtual-router <1-15> preemption to enable or disable master preemption.
When enabled, if this virtual router is in backup mode but has a higher priority than the
current master, this virtual router pre-empts the lower priority master and assumes
control. Even when preemption is disabled, this virtual router always pre-empts any
other master if this switch is the owner (the IP interface address and virtual router
address are the same). By default, this option is enabled.
Example 5-71 Configure preemption
ACC-1#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-1(config)#router vrrp
ACC-1(config-vrrp)#virtual-router 1 preemption
ACC-1(config-vrrp)#
ACC-2#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-2(config)#router vrrp
ACC-2(config-vrrp)#virtual-router 1 preemption
ACC-2(config-vrrp)#
f. Configure the timers (Example 5-72 on page 226).
Run virtual-router <1-15> timers advertise <1-255> to define the time interval
between VRRP master advertisements. This interval can be any integer 1 - 255
seconds. The default value is 1.
Run virtual-router <1-15> timers preempt-delay-time <0-255> to configure the
pre-empt delay interval. This timer is configured on the VRRP Owner and prevents the
switch from moving back to the Master state until the preemption delay interval expires.
Ensure that the interval is long enough for OSPF or other routing protocols
to converge.