Dell BigIron RX Series, Configuration Manual

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466 BigIron RX Series Configuration Guide
53-1002253-01
Configuring additional VRRP and VRRPE parameters
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For VRRP, the software changes the priority of the virtual router to a track priority that is lower
than that of the virtual router priority and lower than the priorities configured on the Backups.
For example, if the virtual router priority is 100 and a tracked interface with track priority 60
goes down, the software changes the virtual router priority to 60.
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For VRRPE, the software reduces the virtual router priority by the amount of the priority of the
tracked interface that went down. For example, if the VRRPE interface’s priority is 100 and a
tracked interface with track priority 60 goes down, the software changes the VRRPE interface’s
priority to 40. If another tracked interface goes down, the software reduces the virtual router’s
priority again, by the amount of the tracked interface’s track priority.
The default track priority for a VRRP Owner is 2. The default track priority for Backups is 1.
You enter the track priority as a parameter with the owner or backup command. Refer to “Track
port” on page 465.
Syntax: owner [track-priority <value> ]
Syntax: backup [priority <value> ] [track-priority <value> ]
The syntax is the same for VRRP and VRRPE.
Backup preempt
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 virtual router. 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 virtual router.
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 returns to be the
Master when it comes back online.
To disable preemption on a Backup, enter commands such as the following.
Router1(config)# inter e 1/6
Router1(config-if-e10000-1/6)# ip vrrp vrid 1
Router1(config-if-e10000-1/6-vrid-1)# non-preempt-mode
Syntax: non-preempt-mode
The syntax is the same for VRRP and VRRPE.
Master router abdication and reinstatement
To change the Master’s priority, enter commands such as the following.