(Optional) Configuring VRRP Smooth Switching
Context
On a network where VRRP groups are configured, the master and backup cannot communicate in real time during the active/standby switchover of the master in the stack system. When the master fails, a backup becomes the master. When the original master recovers, it preempts to be the master again because its priority is higher than the priority of the original backup. The system is busy during the switchover, so Hello packets of the master cannot be sent to the backup. The backup cannot receive the Hello packets, and then preempts to be the master. Packets are lost during this process.
Enabling VRRP smooth switching on a switch in the stack system can optimize the VRRP performance and reduce the impact on user traffic.
After VRRP smooth switching is enabled, the learning function takes precedence over the preemption function. Therefore, the VRRP group status is not switched and service traffic is not affected.
VRRP smooth switching must be configured on each device of a VRRP group.
Procedure
- Run system-view
The system view is displayed.
- Run vrrp timer-advertise learning enable
The device is enabled to learn the interval at which VRRP Advertisement packets are sent.
By default, this function is enabled.
- Run vrrp smooth-switching timer timer-value
VRRP smooth switching is enabled, and the interval contained in VRRP Advertisement packets during VRRP smooth switching is configured.
By default, VRRP smooth switching is enabled and the interval contained in VRRP Advertisement packets is 100s.
The learning function must be enabled before this command is run. When the learning function is disabled, VRRP smooth switching is also disabled.
- If the interval for sending VRRP Advertisement packets on the master is much longer than that on the backup, the Master_Down_Interval timer is reset after the backup is restarted and the interface recovers. The master may not send VRRP Advertisement packets after the Master_Down_Interval timer expires. In this case, the backup becomes the master, and two masters exist in the group.
- During VRRP smooth switching, the master sends VRRP Advertisement packets at the configured interval. If the time for VRRP smooth switching (for example, 1s) is shorter than the interval for sending VRRP Advertisement packets (for example 10s), VRRP Advertisement packets are sent at the configured interval (10s in this example). However, the interval contained in the VRRP Advertisement packet is equal to the time for VRRP smooth switching (1s in this example). As a result, the VRRP group status frequently flaps.