The three message primary test sequence confirms the existence of {TAIL ~ a fully functional bi directional path} between {HEAD ~ the two access points} of a node redundantly connected to a network 
The three message primary test sequence confirms the existence of { TAIL ~ a fully functional bi directional path } between { HEAD ~ the two access points } of a node redundantly connected to a network
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH