[fa.info-vax] TCP and DECnet speed

info-vax@ucbvax.ARPA (10/04/84)

From: Richard Garland <OC.GARLAND%CU20B@COLUMBIA>

A couple of weeks ago Kevin Corasso (Sorry Kevin if I spelled that
wrong) was talking about the DEC DUENA ethernet interface and gave
the following figures:

	DECNET throughput	-	280 kbaud
	TEK TCP/IP throuput	-	140 kbaud

I assume these are between 2 780's running VMS V3.x (x>4) for large
file transfer with little else going on.  Is that the way it was
Kevin?

What I would like to know is:

	1) WHat these numbers depend on as for operating parameters
	(file size, machine loading, Unibus traffic, buffer size etc.)

	2) How does the throughput compare with:
		TWG TCP/IP	(on a similar VAX)
		4.2BSD TCP/IP	(on a Similar VAX)
		the "other" VMS TCP/IP		(forgot the vendor.)

The "other" TCP was mentioned some months ago on this list in a
comparison with TWG TCP.  I can't find these figures.  Does this
list still have an archive somewhere?

What was mildly surprising (not really I guess) is that DECnet out-
performed TCP by so much.  Are these (Kevin's) figures anomolous?
I know DEC banged on DECnet a lot to optimize it over Ethernet but
is TCP really twice as slow.   Is it a more burdensome protocol
for some reason?  Is this just TEK or are other TCP implementations
the same (hence the above query)?  It would be nice to fill in the
blanks in the following chart:

		Network-vendor		Throughput

		DECnet (DEC)		280 kb
		TCP/IP (TEK)		140 kb
		TCP/IP (TWG)		??
		TCP/IP ("other?")	??
		TCP/IP unix 4.2BSD	??

Thanks if anyone can help complete this information.  Remote terminal
support is of course a whole nother comparison which would be interesting
and useful, although somewhat harder (I think) to characterize numerically.
Any ideas how to characterize terminal use over a network?  Anyone with any
numbers.  (DEC says their new DECnet terminal protocol (V4.0) is "much
faster than before" - this is not LAT which is another terminal protocol
which runs on ethernet: "LAT is much faster than DECnet". How much is
"much faster than much faster than ..."?  Oh well. we'll see.)

					Rg
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