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