How do I check a Linux bond and its LACP partner configuration?
A Linux bond can provide different redundancy or aggregation behaviours depending on its mode. IEEE 802.3ad/LACP requires compatible configuration at the switch side; active-backup has different requirements. Aggregation also does not normally make one flow equal to the sum of all member link rates.
Before you start
- A configured Linux bond and provider cooperation for switch-side verification.
Instructions
1. Read the configured bond state
Replace bond0 with the installed bond name. The kernel report includes mode, member status and mode-specific details.
cat /proc/net/bonding/bond0Review active members, link failures, aggregator and partner information when applicable. Do not infer correct switch configuration from the interface merely being up.
2. Confirm member and provider configuration
Inspect the physical links and ask the provider to verify the correct switch ports, LAG membership and hashing policy for the agreed design.
ip -br link
sudo ethtool enp1s0Use the real member interface. A member connected to the wrong switch configuration can create asymmetric or intermittent failures.
Check the result
- Both host and switch agree on the bonding mode and intended members, and controlled failover/throughput checks match the required failure scenario.
Troubleshooting
- One member remains unused
- Check mode, partner state, hashing and whether the test consists of a single flow.
- Adding a second cable breaks connectivity
- Investigate switch aggregation, loops and bond configuration before reconnecting or toggling modes repeatedly.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.