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