What causes intermittent packet loss when load balancing with LACP?

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What causes intermittent packet loss when load balancing with LACP?

Asked on Nov 25, 2025

Answer

Intermittent packet loss when using Link Aggregation Control Protocol (LACP) for load balancing can often be attributed to misconfigurations or mismatches in the LACP settings across the devices involved. LACP is used to bundle multiple physical links into a single logical link to increase bandwidth and provide redundancy, but it requires consistent configuration on both ends of the link aggregation.

Example Concept: LACP operates by negotiating the aggregation of links between two devices, ensuring that both sides agree on which links are active and how traffic is distributed. Packet loss can occur if there are discrepancies in LACP configurations, such as mismatched hashing algorithms, inconsistent LACP modes (active/passive), or if one of the links in the bundle is experiencing physical issues. Proper synchronization and monitoring of link health are crucial to maintaining stable connectivity.

Additional Comment:

Ensure that both ends of the LACP connection are configured with the same LACP mode (active or passive).
Verify that the load balancing algorithm (e.g., source/destination IP, MAC, or port) is consistent across devices.
Check for physical layer issues on individual links within the LACP bundle, such as faulty cables or ports.
Monitor LACP status and logs for any negotiation failures or link state changes.
Consider using network monitoring tools to detect and analyze patterns of packet loss.

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