Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 458)

440 Brocade ICX 6650 Layer 3 Routing Configuration Guide
53-1002603-01
Additional VRRP and VRRP-E parameter configuration
Backup preempt configuration
By default, a Backup that has a higher priority than another Backup that has become the Master
can preempt the Master, and take over the role of Master. If you want to prevent this behavior,
disable preemption.
Preemption applies only to Backups and takes effect only when the Master has failed and a
Backup has assumed ownership of the VRID. The feature prevents a Backup with a higher priority
from taking over as Master from another Backup that has a lower priority but has already become
the Master of the VRID.
Preemption is especially useful for preventing flapping in situations where there are multiple
Backups and a Backup with a lower priority than another Backup has assumed ownership, because
the Backup with the higher priority was unavailable when ownership changed.
If you enable the non-preempt mode (thus disabling the preemption feature) on all the Backups,
the Backup that becomes the Master following the disappearance of the Master continues to be
the Master. The new Master is not preempted.
NOTE
In VRRP, regardless of the setting for the preempt parameter, the Owner always becomes the Master
again when it comes back online.
To disable preemption on a Backup, enter commands such as the following.
Brocade Router1(config)#interface ethernet 1/1/6
Brocade Router1(config-if-e10000-1/1/6)#ip vrrp vrid 1
Brocade Router1(config-if-e10000-1/1/6-vrid-1)#non-preempt-mode
Syntax: [no] non-preempt-mode
The syntax is the same for VRRP and VRRP-E.
Changing the timer scale
NOTE
Changing the timer scale is supported for IPv4 VRRP v2, IPv4 VRRP-E v2, and IPv6 VRRP-E v3. It is
not supported for IPv6 VRRP v3.
To achieve sub-second failover times, you can shorten the duration of all scale timers for VSRP,
VRRP, and VRRP-E by adjusting the timer scale. The timer scale is a value used by the software to
calculate the timers. By default, the scale value is 1. If you increase the timer scale, each timer’s
value is divided by the scale value. Using the timer scale to adjust timer values enables you to
easily change all the timers while preserving the ratios among their values.
Table 80 shows timer
scale values.
TABLE 80 Time scale values
Timer Timer scale Timer value
Hello interval 1 1 second
2 0.5 seconds
Dead interval 1 3 seconds
2 1.5 seconds