STP State for MAC Address Learning on PortFast-enabled Port

PortFast STP State

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In which STP state does MAC address learning take place on a PortFast-enabled port?



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A. B. C. D.


In the Spanning Tree Protocol (STP), PortFast is a Cisco-specific feature that is used to bypass the listening and learning states and immediately put a port into the forwarding state. The purpose of this feature is to allow end devices, such as workstations and servers, to connect to the network without causing STP topology changes.

When a PortFast-enabled port is first brought up, it goes through the following STP states:

  1. Blocking (also known as discarding): During this state, the port does not forward any frames and discards all incoming frames. This is to prevent loops in the network while STP determines the root bridge and the shortest path to it.

  2. Forwarding: During this state, the port forwards frames to their destination. This is the normal state for a port in a healthy network.

However, with PortFast enabled, the port will skip the learning state and go directly into the forwarding state. The learning state is when the port learns the MAC addresses of the devices connected to it. In other words, when PortFast is enabled, MAC address learning takes place in the forwarding state.

Therefore, the correct answer to the question is C. forwarding.