The switching fabric comprises a plurality of data ports through which {HEAD ~ data frames} enter or exit {TAIL ~ the switching fabric} 
exit
The switching fabric comprises a plurality of data ports through which { HEAD ~ data frames } enter or exit { TAIL ~ the switching fabric }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL