-	special qualifiers
	filtering applies only to protocol
	/total:	count since the start of the experiment
(D)	/delta:	count packets and bytes
		received only during the sampling interval
(D)	/initialize :	reinitialize display
	/listen: only count incoming packets to node
	/talk: only count outgoing packets

-	format
source	dest	protocol	bits/s	packets/s	(/delta)
source	dest	protocol	bytes	packets		(/total)

	bits/s and bytes refer to the total size of an ethernet
	frame, including header and trailer. inaccurate for small 802.3 frames