From nowicki@Sun.COM Fri May 12 10:20:01 1989
Date: Fri, 12 May 89 10:14:34 PDT
From: nowicki@Sun.COM (Bill Nowicki)
To: craig@NNSC.NSF.NET
Subject: Re:  average size of Internet datagrams
Cc: end2end-tf@venera.isi.edu
Status: R

	To: end2end-tf@venera.isi.edu
	Subject: average size of Internet datagrams
	Date: Fri, 12 May 89 12:16:00 -0400
	From: Craig Partridge <craig@NNSC.NSF.NET>

	    I did a little testing within my local network and found
	that while the 100 byte number looks pretty accurate for
	traffic gateway out of our Ethernet, the average size within
	the Ethernet was about 700 bytes.  When I looked at individual
	hosts, they too were averaging about 700 bytes.

My informal observations on our internet show that local traffic is
almost all NFS, with many small packets ~150 bytes, and a fair number
of full-sized reads and writes (we have mostly diskless workstations).
This would be consistent with your observations.  Traffic between
buildings tends to be mostly terminal traffic (rlogin/telnet) so there
are many 40 and 41 byte TCP packets.  Traffic between campuses tends to
be almost all SMTP and NNTP, but TCP limits inter-net packets to 512,
and a third of the packets are ACKs, so I could believe an average
close to 100 bytes there too.  Ricardo Gusella is supposed to be doing
some precise measurements and publishing his results one of these days.

	- WIN


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