(Optional) Configuring a VRRP6 Preemption Mode

Context

If the BFD session status monitored by a VRRP6 group flaps frequently or the backups cannot receive VRRP6 Advertisement packets within a specified period, an active/standby switchover is frequently performed. This causes network flapping. The VRRP6 preemption mode and preemption delay can be configured on the switch to enhance the stability of the master and backup.

You are advised to set the preemption delay of the backup in a VRRP6 group to 0, configure the master in preemption mode, and set the preemption delay. On an unstable network, these settings allow a period of time for status synchronization between the uplink and downlink. If the preceding settings are not used, two masters coexist and user devices may learn the incorrect address of the master.

Procedure

Configure non-preemption for the VRRP6 group on the switch.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
4. Run vrrp6 vrid virtual-router-id preempt-mode disable
  The non-preemption mode is configured on the switch.
  
  By default, the device uses the immediate preemption mode.
  
  In non-preemption mode, the master that works properly retains the Master state. This state cannot be preempted even if other switches have a higher priority than that of the master.
  
  You can use the undo vrrp6 vrid virtual-router-id preempt-mode command to restore the default preemption mode.
Configure a preemption mode on the switch and set the preemption delay.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
4. Run vrrp6 vrid virtual-router-id preempt-mode timer delay delay-value
  The preemption delay is set.
  
  By default, the preemption delay is 0, indicating immediate preemption. In immediate preemption mode, a backup immediately assumes the master role when detecting that its priority is higher than the master's priority.