primarily testing bi directional communicative connectivity, via the LAN, between a primary and {HEAD ~ a backup redundant network access point} of {TAIL ~ the set} of network access points 
of
primarily testing bi directional communicative connectivity , via the LAN , between a primary and { HEAD ~ a backup redundant network access point } of { TAIL ~ the set } of network access points
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH