Computer Networking · Advanced level

Advanced level · Module 1: Routing and Switching in Depth · Lesson 2 of 4

Switching Redundancy

Add redundant links without creating loops.

In this lesson you will

  • Explain spanning tree
  • Configure link aggregation

Key concepts

switching loopsspanning treeroot bridgeEtherChannel

The lesson

Redundant switch links create loops that can flood a network. Spanning Tree Protocol (STP) blocks some links and unblocks them if the active path fails.

Choose the root bridge deliberately — usually the core switch — rather than leaving it to chance.

Link aggregation (EtherChannel) bundles several links into one logical link for more bandwidth and resilience.

Step by step

  1. Add redundant links.
  2. Observe blocked ports.
  3. Set the root bridge.
  4. Configure and test EtherChannel.

Practice activity

Add redundancy to the lab switch layer.

Expected result: Redundant switching with a planned root and working aggregation.

Check your understanding

  1. What problem does STP prevent?

    Show answer

    Switching loops.

  2. What does EtherChannel do?

    Show answer

    Bundles several links into one logical link.

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