Backup Modes

As shown in Figure 1, SwitchA and SwitchB form a VRRP group. SwitchA is the master device and SwitchB is the backup device. When SwitchA is working normally, it processes all services and transmits session information to SwitchB through the HSB channel. SwitchB does not process services and only backs up session information.

Figure 1 HSB in active/standby mode (master device is working normally)

When SwitchA fails, SwitchB starts to process services, as shown in Figure 2. Because session information is backed up on SwitchB, new sessions can be set up without interrupting the current session. This improves network reliability.

Figure 2 HSB in active/standby mode (master device fails)

When the original master device () recovers, it becomes the master in preemption mode. In non-preemption mode, retains in Backup state.