TEMPIKLABS
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Privileged EXECDomain 5.0

show etherchannel summary

Provides a highly condensed, easy-to-read table displaying the status of all logical Port-Channels on the switch, the specific physical interfaces assigned to them, and the underlying negotiation protocol (LACP or PAgP) holding the bundle together.

Quick Reference

Execution ModeSwitch#
Privilege Level1 or 15
Primary Diagnostic UseChecking for suspended (s) physical links.
Alternative Commandshow etherchannel port-channel

Reading the Output Table

Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
...
Group Port-channel Protocol Ports
1 Po1(SU) LACP Gi1/0/1(P) Gi1/0/2(P)
2 Po2(SD) PAgP Fa0/10(D) Fa0/11(D)
3 Po3(SU) LACP Gi1/0/3(P) Gi1/0/4(s)

Critical Flags to Memorize

  • SU — The Holy Grail. Indicates the Port-Channel is a Layer 2 link (S) and is currently In Use / Active (U). This means the bundle is functioning perfectly.
  • SD — Indicates the Port-Channel is Layer 2 (S) but is completely Down (D). All physical cables assigned to this bundle are either unplugged or disabled.
  • P — Placed next to a physical port (e.g., Gi1/0/1(P)). It confirms the port successfully passed negotiation and is actively bundled and forwarding traffic.
  • s — Suspended. Indicates a physical port tried to join the bundle but was rejected (usually due to a speed/duplex mismatch or a misconfigured native VLAN). The bundle survives, but operates at reduced bandwidth.

CCNA Exam Gotchas

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S vs. s (Case Sensitivity Matters)

The CCNA will absolutely test your attention to detail regarding capitalization in the flag legend.
• A capital S refers to the entire logical Port-Channel and means it is operating at Layer 2.
• A lowercase s refers to an individual physical port and means it has been suspended from the bundle.

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Detecting the Stand-Alone (I) State

If you look at the Ports column and see Gi1/0/1(I), it means the port is up, but the EtherChannel protocol failed to negotiate with the neighbor (e.g., one side is set to LACP and the other to PAgP). The switch falls back to treating it as an independent, unbundled port, which Spanning Tree will likely block to prevent a loop.