Can you explain BackboneFast?
In the network backbone, or even core layer, a totally different method would be used to shorten STP convergence. It operates by having a switch actively determine whether or not alternative paths are available to the root bridge, in the event the switch detects an indirect link failure. Indirect link failures happen when a link which is not directly connected to a switch fails. A switch detects an indirect link failure any time it receives inferior BPDUs from its designated bridge on both its very own root port or a blocked port.
