Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!ames!ucbcad!ucbvax!BRL.ARPA!mike
From: mike@BRL.ARPA (Mike Muuss)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Ethernet Suffering
Message-ID: <8705020210.aa12838@SEM.BRL.ARPA>
Date: Sat, 2-May-87 02:10:46 EDT
Article-I.D.: SEM.8705020210.aa12838
Posted: Sat May  2 02:10:46 1987
Date-Received: Tue, 5-May-87 00:52:28 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 23

Two Sun-3/50 processors blasting to each other with a TCP connection
can achieve ~2-3 Mbits/sec user-to-user throughput (tested with the TTCP
program), and seem to use about 25% of the ethernet bandwidth as
monitored on another Sun-3/50, which has unknown (to me) measurement
accuracy.  In our experiences this has had no noticable impact on other
users of the Ethernet.  Adding a second pair of Sun-3/50s running the
same test doubled the loading on the Ethernet, as you would expect.

Current wisdom suggests that there should be no more than one file
server and 8 diskless Sun-3s per Ethernet for good Ethernet performance
when all the Suns are busy.  At BRL, we presently have one Ethernet with
14 Sun-3/50s and and 4 Sun-2/50s running off of one fileserver (a Gould
PN9050 giving both ND and NFS service), as well as a variety of other
machines (more Goulds and 2 Alliant FX/8s) that communicate with NFS
on a more occasional basis.  We find that head contention on the
file server is the performance limit now, not the Ethernet.  However,
once the filesever is beefed up a bit, the Ethernet will be next, so
the Ethernet will be split into two, with a pair of level-3 IP gateways
between them.

Hope this information helps.
	Best,
	 -Mike