Combination of Port Types on the Root Bridge
Question
A root bridge in an RSTP network is connect to other neighboring bridge using point-to-point links. Which combination of port types can exist on the root bridge?
Answers
Explanations
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A. B. C. D.C
In an RSTP (Rapid Spanning Tree Protocol) network, the root bridge is the central bridge that all other switches connect to. The root bridge is responsible for forwarding traffic between all switches in the network, and it is also responsible for selecting the best path for forwarding traffic.
When the root bridge is connected to other neighboring bridges using point-to-point links, there are only two types of ports that can exist on the root bridge:
Root port: The port on the root bridge that connects to the neighboring bridge with the lowest path cost is called the root port. This port receives the root bridge's configuration BPDU (Bridge Protocol Data Unit) and sends its own configuration BPDU to the neighboring bridge.
Designated port: The port on a non-root bridge that is selected as the forwarding port for a particular network segment is called the designated port. In other words, the designated port is the port on a non-root bridge that is responsible for forwarding traffic for a particular network segment. On the root bridge, there are no designated ports because it is the central bridge and all other switches connect to it.
Alternate ports are ports that are in the blocking state and are ready to replace a failed designated port. However, since there are no designated ports on the root bridge, there can be no alternate ports on the root bridge.
Therefore, the correct answer is C: All ports on the root bridge are designated ports.
