secondarily testing, upon determining loss of communicative connectivity between the primary and backup network access points, connectivity between the set of network access points and a set of {HEAD ~ nodes} on {TAIL ~ the LAN} to which the redundantly connected node previously communicated; and 
secondarily testing , upon determining loss of communicative connectivity between the primary and backup network access points , connectivity between the set of network access points and a set of { HEAD ~ nodes } on { TAIL ~ the LAN } to which the redundantly connected node previously communicated ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH