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From: jqj@cornell.UUCP (J Q Johnson)
Newsgroups: net.unix-wizards
Subject: Re: IBM DACU
Message-ID: <240@cornell.UUCP>
Date: Sat, 31-Aug-85 13:17:05 EDT
Article-I.D.: cornell.240
Posted: Sat Aug 31 13:17:05 1985
Date-Received: Mon, 2-Sep-85 04:03:43 EDT
References: <1108@brl-tgr.ARPA>
Reply-To: jqj@cornell.UUCP (J Q Johnson)
Organization: Cornell Univ. CS Dept.
Lines: 19

In article <1108@brl-tgr.ARPA> root%bostonu.csnet@CSNET-RELAY.ARPA writes:
>P.S. We are using the DACU on ethernet here at BU on our 3081, transfer
>rates seem analagous to UNIX::UNIX transfers and are likely limited by the
>remote end (eg. VAX.) That is, tranfer rates using FTP on a clear day will
>oscillate around 20KBytes/second (as reported by FTP)

If you are getting only 20KB/sec. VAX<=>VAX then your tcp needs tuning.  A
reasonable throughput level is twice that or better (I just tried transfering
vmunix from one 780 to another, each with 3com ifs, and got 41KB/sec with
loads of 1.8 and 1.4).  On the other hand, we are seeing somewhat worse
ftp rates through the DACU on our 3081; seems like we need help from Barry
with tuning.

Another point on the DACU is that the Wiscnet software has extremely high
cpu overhead, particularly for lots of small packets (e.g. multiple telnet
connections, though presumably tn3270-style interactions involve larger
packets).  I don't have any statistics off hand, but would be interested
in any that other DACU users might have.  How much of a 3081 gets burned
running 40 active telnet connections, for example?