Each STS3 C link carries {TAIL ~ 640 DS0 channels} per {HEAD ~ 125 microsecond frame} 
Each STS3 C link carries { TAIL ~ 640 DS0 channels } per { HEAD ~ 125 microsecond frame }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD