Hi HI
STP ensures a loop-free network but has a slow network topology convergence speed, leading to service deterioration. If the network topology changes frequently, the connections on the STP-enabled network are frequently torn down, causing frequent service interruption. Users can hardly tolerate such a situation.
Disadvantages of STP are as follows:
Port states or port roles are not subtly distinguished, which is not conducive to the learning and deployment for beginners.
A network protocol that subtly defines and distinguishes different situations is likely to outperform the others.
Ports in the Listening, Learning, and Blocking states do not forward user traffic and are not even slightly different to users.
The differences between ports in essence never lie in the port states but the port roles from the perspective of use and configuration.
It is possible that the root port and designated port are both in the Listening state or Forwarding state.
The STP algorithm determines topology changes after the time set by the timer expires, which slows down network convergence.
The STP algorithm requires a stable network topology. After the root bridge sends configuration Bridge Protocol Data Units (BPDUs), other routers forward them until all bridges on the network receive the configuration BPDUs.
This also slows down topology convergence.
In STP, after the topology becomes stable, the root bridge sends configuration BPDUs at an interval set by the Hello timer. A non-root bridge does not send configuration BPDUs until it receives configuration BPDUs sent from the upstream router. This renders the STP calculation complicated and time-consuming. In RSTP, after the topology becomes stable, a non-root bridge sends configuration BPDUs at Hello intervals, regardless of whether it has received the configuration BPDUs sent from the root bridge. Such operations are implemented on each router independently.
