US Patent 11153199 Forwarding path failure detection using packet loop

A packet loop runs between two participating endpoint network devices, and in particular runs in the respective data planes of the endpoint devices. A probe packet is provided to the data plane of an initiating device and is forwarded to the other device to initiate the packet loop. The source and destination addresses in the probe packet are set equal to a common address. Based on the common address, entries in the respective forwarding tables of the endpoint devices are established to point to each other so that the probe packet is forwarded back and forth between the two devices thus sustaining the packet loop. A broken loop indicates a forwarding path failure at which time corrective action to be taken.