Rapid Convergence

Faster convergence compared to legacy spanning tree algorithm is the most important feature in RSTP. RSTP relies on two new variables to achieve this situation:

• Edge port - Ports that are directly connected to end stations do not create bridging loops. Thus, they rapidly transition to forwarding, skipping the learning and listening states. The topology change is not triggered when the link toggles on an edge port. Whenever a BPDU is received on an edge port, it loses its edge-port status and becomes a normal spanning tree port. PVRST+ uses the portfast keyword for edge-port configuration.

• Link types - PVRST+ achieves rapid transition on point-to-point links. The link type is automatically derived from the duplex mode of a port. A port operating in full-duplex is assumed to be point-to-point, but a half-duplex port is considered as a shared port by default. This automatic link type setting can be overridden by explicit configuration.