30.2.5 Clearing MAC address tables during GSRP network switching

When the Ring Protocol and GSRP are used together and GSRP network path switching occurs, the MAC address tables of the devices configuring the ring network need to be cleared. If these MAC address tables are not cleared, communication might not be restored in a timely manner. The MAC address tables of the devices on the ring network can be cleared by using the virtual link VLANs set on the ring network during the transition to the GSRP master to send flush control frames for the ring network. This virtual link VLAN must belong to the VLAN for data transfer group for the Ring Protocol.

When a flush control frame sent by the GSRP master is received by a device in the ring, its MAC address table is cleared. Note that the sending count follows that in the GSRP configuration (flush-request-count).

When the Ring Protocol and GSRP are run on different VLANs, each protocol is unaffected by any path switching occurring due to faults. Therefore, because the MAC address tables do not need to be cleared, virtual link VLANs do not need to be set.