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CCNA · 200-301Intermediate

EtherChannel: LACP Mode Mismatch

Two healthy trunk links refuse to bundle, and each member sits suspended. Compare both ends, correct the negotiation protocol, and verify the port channel yourself, live, right below.

Interactive simSwitchingEtherChannelLACP

Symptom

A two-link uplink should bundle, but each member remains individual. Compare both ends, correct the LACP mode, and verify the port channel.

Your mission

Prove the cause, then fix it

Format

Guided CLI investigation

Start interactive labSee the investigation plan ↓Need a hint? Reveal the root cause ↓
EtherChannel: LACP Mode Mismatch

Investigate before you configure.

Use the CLI evidence to isolate the fault, make the smallest safe correction, then verify the network state changed.

Observe the symptom and link state.

Diagnose by comparing the protocol evidence.

Verify the expected device state and confirm the original symptom is resolved.

Console access: SW1 · SW2

This workspace stacks for portrait phones. Rotate to landscape for the full split-screen console.

Need a hint?

Reveal the root cause when you're ready.

Try the investigation first, then use this as your escape hatch, not a dead end.

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Lab debrief

Turn the session into a repeatable troubleshooting pattern.

Use this reference after your attempt: first explain the symptom, then verify the evidence, then confirm the repair.

The problem

SW1 and SW2 are connected by two healthy trunk links. The intended port channel never forms: SW1 negotiates with LACP while SW2 was configured with PAgP, so each member stays suspended and the bundle never comes up.

What you'll practice

  • Read EtherChannel summary flags
  • Compare LACP mode and channel-group settings on both switches
  • Recognize active/passive negotiation requirements
  • Repair a port-channel configuration without creating a loop
  • Verify both links are bundled

The topology

Two access switches connect over two parallel 802.1Q trunk links carrying user VLANs. The topology is intentionally minimal so the port-channel state is the evidence, not a hidden routing dependency.

Commands to run yourself

The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.

Check bundle and member state
show etherchannel summary
Inspect LACP neighbors
show lacp neighbor
Compare switchport settings
show interfaces trunk

Topology diagram

Frequently asked

Must both LACP sides use active mode?

No. At least one side must be active; active/passive forms an LACP bundle, while passive/passive does not initiate negotiation.

Ready to run this lab yourself?

No setup, no image sourcing. Book a session or ask for a live demo.

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