Optical fiber network card bond aggregation mode selection and verification

How to choose the bond aggregation mode of dual-port fiber optic network card: configuration and verification of active/standby and LACP

Published: 2025-09-05 EB-LINK Views: 1619 bond aggregation, LACP, active/standby switching, dual-port network card

It is a waste to only run one port of a dual-port fiber optic network card. Most projects will do bond aggregation. However, the pitfalls are that the mode is not aligned with the switch, and the monitoring parameters are not adjusted properly. When a fault occurs, switching is not easy. This article talks about mode selection and verification before going online.

The difference between active and standby and LACP

mode1 active-backup has only one active port at the same time. It switches over in case of failure. No configuration is required on the switch side. It is suitable for scenarios where a single switch or link conditions are unequal. mode4 802.3ad is LACP, which solves load balancing and failover together, but requires the switch side to put the ports into the same aggregation group. If the modes on both sides are inconsistent, the connection will be on and off. The mode0 balancing round has the risk of being out of order and is rarely used in production networks.

Configuration order and consistency on both sides

In the mode4 scenario, first enable LACP on the switch, and then write bond mode, miimon and xmit_hash_policy in Linux. The order cannot be reversed.
PCI-EX16 25G four-port optical fiber network card (Intel E810 chip)Try to connect multiple ports to the same aggregation group of the same switch. Cross-switches require stacking or M-LAG solutions.
Both sides of the optical port are equipped with the same typeSFP+ 10G single-mode dual-fiber 10km optical module, do not mix single fiber and double fiber

Before going online, unplug the fiber once to do a switching test.

After the bond is established, use cat /proc/net/bonding/bond0 to check the status of each slave; physically disconnect an optical fiber during low business peaks and observe the switching time and upper-layer session recovery time. When miimon is not configured or the detection cycle is too long, the active/standby switching is not fast. Such actual measurement records should be written into the acceptance document. Do not just screenshot the output of a command.

Aggregation solves the overlay of availability and bandwidth. MTU and multi-queue still need to be set separately on the bond port. If you are not sure about the configuration, you can contact EB-LINK technical support for a reference list, call 0755-83179002.