LACP and Port-Channel Troubleshooting Tips
Diagnose missing bundle members, suspended links, hashing surprises and inconsistent port-channel state.
Separate bundle state from member state
A port-channel can remain up while one member is failed, suspended, or excluded. Check the logical bundle and every physical member so reduced capacity or redundancy does not go unnoticed.
Record which members are collecting and distributing traffic, which are standby, and which are rejected. That quickly separates negotiation, consistency, and physical problems.
Compare attributes that must match
Bundle members generally need compatible speed, duplex, MTU, VLAN mode, and other platform-specific settings. A small config difference can keep a physically up interface out of the bundle.
Compare the far-end bundle, LACP system information, and cabling. A mispatched link can look very similar to a configuration mismatch.
Understand hashing before calling traffic uneven
Port-channels distribute flows by a hash; they do not guarantee equal byte counts on every member. A few large flows can make one link look busy while another is quiet without indicating failure.
If a member is truly lost, treat the bundle as a redundancy and capacity risk. After restoration, verify that the member rejoins, traffic distributes, and counters remain clean.