After the routing data is added to the data frame, the buffer transmits {HEAD ~ the data frame} to {TAIL ~ the switching system} 
to
After the routing data is added to the data frame , the buffer transmits { HEAD ~ the data frame } to { TAIL ~ the switching system }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL