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Date:      Thu, 7 Dec 1995 14:12:56 +0000
From:      "Andrew Webster" <>
Subject:   Explain this!
Message-ID:  <>

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Having recently upgraded a FreeBSD system from 2.0 to 2.1, I was left 
scratching my head over a strange performance related problem...

The old system, FreeBSD 2.0-RELEASE on a 486/33, 16MB with AHA-1542,
SMC8013 AST/4 port network card was getting a little long in the
tooth with various quirks & oddities so I decided to upgrade it. The
new system: FreeBSD 2.1.0-RELEASE on a 486/66, 24MB with AHA-1542,
VLB S3 video, Digiboard PC/4, 3C509B NIC.

I noticed that during large FTP xfers between my dos/windows box
running winsock and the FreeBSD machine I was getting many timeouts,
and FTP's (TCP's?) incremental backoff routine made the transfers
excruciatingly long.  Winsock was reporting many "unacceptable
segemnts" and was backing off longer and longer each time.  For the
record, the dos box is a 486/66 with a 3C509B in it.

On a hunch, I put the SMC8013 back into the new machine, and now it 
works as fast (maybe faster) than it used to!

This leaves me wondering:
	1. Is the 3C509 card a piece of junk?
		It works okay on my dos box with the SMC card in the BSD box!

	2. Is the ep0 driver corrupting data packets?
		I tried all sorts of MTU sizes on the dos box, it still didn't
		work any better.

	3. Is the ep0 driver dropping ack packets from the FTP client?
		Don't know.

Anyone care to comment on this?


  Andrew Webster   Network Manager / Special Projects
  Dataradio Inc.   200-5500 Royalmount Ave.      TEL: +1 514 737 0020
  Town of Mount Royal, QC, CANADA  H4P 1H7       FAX: +1 514 737 7883              Email:

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