A network engineer checks EtherChannel status on a switch and sees the following output:
Group Port-channel Protocol Ports ------+-------------+---------+----------------------------- 1 Po1(SD) LACP Gi1/0/1(s) Gi1/0/2(I)
What is the most likely reason the EtherChannel is not forwarding traffic?
Answer choices
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
The member interfaces have mismatched speed or duplex settings
Speed or duplex mismatches can definitely break an EtherChannel, which makes this option tempting. The problem is that the exhibit does not specifically prove that speed or duplex is the issue. It only proves that the links are not bundling correctly. On exam-style questions, choose the conclusion directly supported by the output before jumping to one of several possible hidden causes.
The port channel is Layer 3 instead of Layer 2
A Layer 3 port-channel can work perfectly well when intentionally configured that way, so the phrase 'Layer 3' does not explain the failure on its own. The real problem shown here is that the member interfaces are not joining the logical channel correctly. The status flags point to a bundle formation problem, not simply to the channel being Layer 3 or Layer 2.
At least one member interface is not bundled correctly, so the logical channel is down
Correct. This is correct. The logical EtherChannel is down because the physical members are not properly bundled. The status display is telling you that the switch did not build a working aggregated link, so the port-channel cannot carry traffic as intended.
LACP requires exactly four links to form a bundle
LACP does not require four links. Two-link EtherChannels are extremely common, and LACP can negotiate bundles with fewer than four member interfaces. The issue is not link count. The issue is that the displayed interfaces are not in a healthy bundled state.
Common exam trap
A frequent exam trap is selecting speed or duplex mismatch as the cause simply because it is a common EtherChannel issue. However, the provided output only shows that one interface is suspended (I) and another is bundled (s), indicating a bundle formation problem rather than a specific configuration mismatch. Another trap is assuming that the port-channel being Layer 3 causes the failure, but Layer 3 EtherChannels can forward traffic correctly if configured properly. Also, some might incorrectly believe LACP requires exactly four links, which is false since LACP supports bundles with fewer links. The key is to focus on the status flags showing that the logical channel is down due to member interface suspension.
Technical deep dive
EtherChannel technology allows multiple physical links to be aggregated into a single logical link, increasing bandwidth and providing redundancy between switches. Cisco supports EtherChannel using protocols like LACP, which dynamically negotiate link bundling. Each physical interface in the bundle must have matching configurations such as speed, duplex, VLAN trunking, and channel-group parameters to successfully form the logical port-channel. The switch uses status flags to indicate whether each member interface is bundled (s) or suspended (I). When LACP is used, the protocol exchanges negotiation packets to ensure both ends agree on the bundle membership. If any interface is suspended, it means the switch has detected a configuration mismatch or protocol disagreement preventing that interface from joining the bundle. The port-channel interface itself will not forward traffic until all member interfaces are properly bundled and the logical link is up. Troubleshooting involves verifying consistent settings across all member interfaces, including trunk modes, allowed VLANs, native VLANs, and channel-group numbers. A common exam trap is to assume that speed or duplex mismatches alone cause the bundle failure, but the output only shows the bundle status, not the root cause. Another trap is to think that the number of links or Layer 3 vs Layer 2 port-channel type causes the failure. In reality, the suspended interface flag indicates a bundle formation problem, which could stem from various configuration mismatches. Understanding how to interpret EtherChannel status flags and recognizing that the logical port-channel is down due to member interface suspension is critical for CCNA exam success and real-world troubleshooting.
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
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FAQ
EtherChannel bundles multiple physical interfaces into a single logical link to increase bandwidth and provide redundancy.
The correct answer is: At least one member interface is not bundled correctly, so the logical channel is down — The safest conclusion from this output is that the member interfaces are not successfully participating in the bundle, so the logical port-channel is down. Cisco exam questions often test whether you can read the status flags without overcommitting to a very specific root cause that the exhibit does not explicitly prove. One member is suspended and another is not bundled into the channel correctly, so the EtherChannel never reaches a healthy forwarding state. In the real world, that can happen because of trunk mismatches, allowed VLAN mismatches, native VLAN problems, inconsistent channel-group settings, or negotiation issues. The key exam skill is recognizing that the bundle itself failed, not guessing one hidden configuration line that is not shown.
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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