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 nodes on {TAIL ~ the LAN} to which {HEAD ~ the redundantly connected node} previously communicated; and 
to communicated
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 nodes on { TAIL ~ the LAN } to which { HEAD ~ 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 OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH