In some embodiments, a system includes a first router and a second router both configured to be included within an OTN. The first router is configured to send to the second router a first signal having an ODU with a path delay measurement (DMp) bit set. The first router is configured to, in response to not receiving within a path-length-dependent time period from the second router a second signal having the DMp bit set, (1) trigger a protection action at the first router, and (2) send to the second router a signal configured to notify the second router to trigger the protection action at the second router. The second router is configured to, in response to receiving the signal configured to notify, trigger the protection action at the second router.