EtherChannel

Bundle multiple Ethernet links into one logical channel.

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What is it?

EtherChannel bundles compatible physical links into one logical port-channel. LACP can negotiate the bundle using active/passive modes.

Why should I learn it?

Bundled links behave as one path, so understanding the bundle logic prevents chasing individual-link symptoms that are actually LACP mismatches.

How it works

Compatible physical links negotiate via LACP/PAgP → bundle forms → traffic load-balances across members as one logical link.

Real-world example

Instead of STP treating three links as three separate Layer-2 paths, the port-channel is handled as one logical link while LACP tracks member compatibility.

Troubleshooting mindset

If one member is missing, compare that interface with working members: trunk/access state, VLAN settings and LACP configuration.

Common mistake

Do not memorise the definition without connecting it to packet flow, device state and verification. Ask: what should happen, what actually happened, and which command or capture can prove the difference?

Quick recap

  • Understand the job of the protocol or feature.
  • Know where it sits in the traffic path.
  • Verify behaviour instead of guessing.
  • Connect the topic to the next networking layer.

Interview connection

Explain the concept in simple words first. Then give one practical example or troubleshooting check. That is stronger than repeating a textbook definition.

References & Further Reading

  • How to Master CCNA — supplied reference material.
  • CCNA Notes — supplied technical/configuration reference.
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