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Difficulty: EasySpanning Tree Protocol Operations

Place the standard 802.1D Spanning Tree Protocol (STP) port state transitions in the correct chronological order from initial switch port activation to full operational traffic handling.

  1. 1Blocking State: Discards user data frames and does not learn MAC addresses, but receives and processes BPDUs.
  2. 2Listening State: Evaluates BPDUs to determine root bridge election and port roles without populating the MAC table.
  3. 3Learning State: Inspects incoming frames to populate the MAC address table while still holding user data traffic.
  4. 4Forwarding State: Transmits and receives user data frames while continuously updating MAC address table entries.

Answer

The correct sequence of standard 802.1D STP port states from activation to active traffic forwarding is Blocking State, Listening State, Learning State, and Forwarding State.
Standard 802.1D Spanning Tree Protocol transitions switch ports through four sequential states upon activation: Blocking (prevents loops, reads BPDUs), Listening (elects root bridge and determines port roles), Learning (populates the MAC address table without forwarding data), and Forwarding (fully processes user data frames).

Step-by-Step Solution

1
Determine initial state upon switch port initialization
The port starts in the Blocking state, dropping data frames to prevent topology loops while reading BPDU control frames.
STP must enforce loop prevention immediately before allowing active participation.
2
Identify the topology election phase
The port transitions to the Listening state to process BPDUs and decide root bridge and port role assignments.
Roles must be settled before the switch modifies its MAC address tables.
3
Identify the MAC address table population phase
The port enters the Learning state, recording source MAC addresses without forwarding user data frames.
Pre-populating the MAC table prevents unnecessary frame flooding when data transmission begins.
4
Identify the final operational state
The port moves to the Forwarding state to send and receive all network traffic.
Convergence is complete and the link is verified as loop-free.

Key Concept

Spanning Tree Protocol (802.1D) Port State Transitions
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Topics

Spanning Tree Protocol Operations

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