RSTP: Cisco Certified Network Associate Exam | Cisco Exam 200-125


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Which three statements about RSTP are true? (choose three)



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A. B. C. D. E. F.


RSTP (Rapid Spanning Tree Protocol) is an improved version of the STP (Spanning Tree Protocol) that provides faster convergence and recovery times in the event of link failures in a network. Here are the explanations for the true statements about RSTP:

A. RSTP significantly reduces topology reconverging time after a link failure: When a link fails in a network, the Spanning Tree Protocol (STP) can take up to 50 seconds to converge and reestablish connectivity. RSTP, on the other hand, can converge the network in as little as a few seconds. This is achieved by introducing a new port state, called the "discarding" state, which allows RSTP to quickly detect and respond to changes in the network topology.

B. RSTP expands the STP port roles by adding the alternate and backup roles: In addition to the root, designated, and non-designated roles that exist in STP, RSTP introduces two new roles for ports: alternate and backup. These roles are used to speed up the convergence time when a link fails.

C. RSTP port states are blocking, discarding, learning, or forwarding: RSTP introduces a new port state, the discarding state, which is used to replace the blocking state in STP. The other port states, learning and forwarding, are the same as in STP.

D. RSTP also uses the STP proposal-agreement sequence: RSTP uses a similar proposal-agreement sequence to STP to determine the root bridge and the path cost to the root. However, RSTP can transition to the forwarding state more quickly than STP.

E. RSTP uses the same timer-based process as STP on point-to-point links: RSTP uses the same Hello protocol and timer-based process as STP on point-to-point links. However, RSTP can transition to the forwarding state more quickly than STP.

F. RSTP provides a faster transition to the forwarding state on point-to-point links than STP does: RSTP can transition to the forwarding state more quickly than STP on point-to-point links. This is achieved by immediately moving a port from the discarding state to the forwarding state when a BPDU is received, rather than going through the learning state.