In operation, {HEAD ~ network access tier devices} collect {TAIL ~ security information} about each connected end user device serviced by the access device 
collect
In operation , { HEAD ~ network access tier devices } collect { TAIL ~ security information } about each connected end user device serviced by the access device
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH