Rapid Spanning Tree Protocol (RSTP) was developed to replace the STP. The latter was designed to prevent loops from developing in a switched network but it is not efficient considering the processing abilities of the advanced equipment. It improves on the performance of STP, by reducing converge times on the network switches, on the link failure and at start up. In what ways does the RSTP improve the STP?
The best way of looking at the STP’s function is through the scenario of city traffic. If the city’s control points are non-functional, congestion will be inevitable. It means then, if the STP does not control the formation of loops in the network, it might come to a standstill. The first function of the STP is to create a link with the switched network. Where this is the only switch in the network, it becomes the root bridge. This is selected initially in the network and the rest of the network is developed around it. Then, there is a second selection, which is dependent on the Bridge ID. This is encoded by the manufacturer on the switch.
The switch priorities and the bridge IDs are transported via the Bridge Protocol Data Units, which are sent using the RSTP on each “hello” interval or two seconds. The bridge with the highest bridge ID or superiority is chosen as the root bridge. STP and RSTP major difference is in the way they converge. In the STP networks, a period of 15 seconds must erupt, before deciding on the bridge, which will become the root bridge and the interface, which will be the root interfaces. On the other hand, the RSTP is faster since it uses a proposal and agreement proposal, which reduces the time required to for an interface to proceed to a forwarding state.
Lastly, the STP and RSTP are different in the way they reference their port states. STP has the following port states blocking, listening, learning, disabled and forwarding. On the other hand, RSTP has three port states namely learning, discarding and forwarding. RSTP saves time and ensures efficient prevention of network loop.