Fail to form a LACP bond at boot with messages "An illegal loopback occurred on adapter"

Solution Verified - Updated -


When the system boots, one of the interfaces in a LACP bond doesn't become online and is in marked as "churned" in the bond. These kind of messages are logged by the kernel:

bond0: An illegal loopback occurred on adapter

If the bond is bring down and up again, it becomes online.


  • Red Hat Virtualization Host (RHVH) 4.3.9
  • kernel-3.10.0-1127.el7.x86_64
  • Ethernet controller [0200]: Broadcom Inc. and subsidiaries BCM57412 NetXtreme-E 10Gb RDMA Ethernet Controller [14e4:16d6] (rev 01) with firmware version

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