Dears：

Thank you for your assistance. I have a S922 server that has recently been frequently reported error related to LACP out of sync, than recovery immediately, and there is no link error.

The network switch has no error, and LACP transfers health.

I want to find the root cause, and needs your help. Thank you very much.

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Bowen Dai
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Hi Bowen, 

Found this IBM Support doc related to the same error.
https://www.ibm.com/support/pages/ibm-aix-troubleshooting-echportoutofsyn-errors-ieee-8023ad-link-aggregationlacp-etherchannel

Can you try the steps and resolution mentioned in the above link...

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Saikrishna Akkela
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Root cause probability: 1. cable/connector, 2. SFP+ on any side (LAN card or switch), 3. firmware in LAN card (check from HMC). 

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Igor Novotny
MHM Computer, a.s.
Czech Republic
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Hi

what is the status of primary aggregation status is Negotiating  ,as per below screen shot and the status should be Aggregated , please double check the configuration from switch side.

• Negotiating: LACP is in progress, but the switch has not yet aggregated the adapters. If the Link Aggregation remains on this status for longer than one minute, verify that the switch is correctly configured. For instance, you should verify that LACP is enabled on the ports.
• Aggregated: LACP has succeeded, and the switch has aggregated the adapters together.

https://www.ibm.com/docs/en/aix/7.2.0?topic=configuration-ieee-8023ad-link-aggregation-troubleshooting

also please check from HW side if there's any issue reported on PCI adapter ( Cable / SFP or FW)

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Anas AlSaleh
IBM Power Systems Software Specialist
Saudi Business Machines ( SBM )
Riyadh
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I assume the following are true where the LACP errors are being generated:

1. It's on a VIO server(s).
2. The ports were all IN_SYNC for at least a month before going live.
3. No known changes made from the VIOs or Network(switches) side.
4. Using both Etherchannel and SEA

Unfortunately, when it comes to network issues, often times you have to rule out your own environment first before engaging the network team. In this case, if you want to find out the root cause, start with process of elimination by removing each port out of your Etherchannel and test. 

Good luck.

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Angel Bugarin
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> Unfortunately, when it comes to network issues, often times you have to rule out your own environment first before engaging the network team

Having visibility to your adjacent environments is a must.

Unless you know how to interpret a tcpdump, ask the network team to enable LLDP, and to check if LACP is long or short.  (Recommended setting is "long" on both sides, but as long as both side are configured for the same value, it should work).

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José Pina Coelho
IT Specialist at Kyndryl
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Original Message:
Sent: Mon October 27, 2025 10:22 AM
From: Angel Bugarin
Subject: PORT LACP FAILURE

I assume the following are true where the LACP errors are being generated:

1. It's on a VIO server(s).
2. The ports were all IN_SYNC for at least a month before going live.
3. No known changes made from the VIOs or Network(switches) side.
4. Using both Etherchannel and SEA

Unfortunately, when it comes to network issues, often times you have to rule out your own environment first before engaging the network team. In this case, if you want to find out the root cause, start with process of elimination by removing each port out of your Etherchannel and test. 

Good luck.

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Angel Bugarin
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