TCP/IP Networking on Twisted Pair with a Sun SPARC 2

[Richard G. Anderson]

While it pains me to admit it, I have a friend in Cleveland.  He used to
work in Washington, but preferred nice housing and food for his family
over three hours per day commuting...  (is that rational?)  He has asked
that I post this to comp.sys.sun.  Replies may be U.S. Mailed to him or
sent to me.  Cleveland isn't on usenet yet.

                 -- Richard Anderson, Federal Reserve Board

Help!  I am trying to get a Sparcstation2 to work with PC's on a twisted
pair Ethernet.   The trouble is that I can send stuff to the Sun very
quickly, but sending from the Sun to PC's is extremely slow.  Here's the
hardware layout:

An AUI cable runs from the Sun to a 10-BaseT transceiver made by
ExpressNet.  The transceiver is connected by an eight wire twisted pair
modular cable to twisted pair wiring in the wall, terminating in a wiring
closet.  There we have a Wang 10-BaseT concentrator.  We also have several
PC's (in different offices) with 3C503TP boards which also have modular TP
cables that run into the wall, to the wiring closet, and into the Wang
concentrator.  Also connected is a 386 acting as a Banyan Vines server.
Not only that, but the knee bone's connected to the ... thigh bone, an'
the thigh bone's connected to the ... hip bone, and the hip bo -- Well,
you get the idea.  

On the Sun, I made appropriate entries in the /etc/ethers, /etc/hosts, and
/etc/networks files for several PC's.  On the PC I have tried FTP software
from both Beame and Whiteside, Inc., and from FTP Software, Inc.  What
happens with both is that I can upload files from the PC to the Sun very
quickly, at rates of about 80 - 100 KBytes per second.  But sending files
from the Sun to the PC is very slow, only about 1200 - 1500 bytes per
second.  No such delays are evident when I use another PC as an FTP server
and transfer files back and forth from it to my PC, so I don't think my PC
is the problem.  The problem is also noticeable when I use my PC with
VT220 emulation software: with no one else using the Sun I still get
unpredictable delays of a second or two in screen updates and local
echoing of characters I type.  Finally, I have also tried Beame and
Whiteside's NFS, and again I find that uploading to the Sun is very quick,
but downloading is so slow that files much larger than a few Kbytes seem
to hang the PC.

The Expressnet transceiver (which is hooked to the Sun) has lights on the
side to indicate Signal Quality Error, Link Status, Power, Transmit, and
Receive.  I've noticed that the Collision and Transmit lights often blink
on and off together when the Sun is sending something.  This happens quite
a lot even when I'm the only person on the network. 

I have tried swapping the AUI cable, the transceiver, and the cable from
transceiver to the wall.  I've also tried moving the Sun to another room
so as to make use of a different pair of wires to the closet.  None of
this has made any differnce at all.  Since the PC's on the network seem to
communicate just fine, I'm led to believe that the Sun is the problem. 

The Sun is still under warranty, so I called the 800 number for help.  The
rep I talked to is trying to be helpful by sending me a new CPU board and
referring me to the software people, but he doubts that it actually is a
hardware problem.  What he thinks might be happening is this:  The Sun
sends out a packet and waits a very short time for an acknowlegement.  The
PC is too slow to respond in such a short time.  So the Sun knocks its
transmission speed down a step and tries again.  The process repeats
itself until the Sun finds a speed the PC can handle.  The trouble arises
because the step down in transmission speed is exponential, which means
that things slow down very quickly indeed.

I don't whether to believe this story or not.  Unless I missed something,
it doesn't explain why I see that collision light blinking on so often.
It also leads me to wonder why I don't have any trouble sending things
between PC's on the network.  I would have thought that the Ethernet and
10-BaseT specifications define procedures for negotiating transmission
speeds between devices.  If these procedures work the same way on the PC's
as they do on the Sun, I should be having the same troubles everywhere.

So I'm asking the net for help.  Has anyone out there tried to put the SS2
on a twisted pair ehternet with PC's?  Did it work for you?   How did you
do it?  Would a faster NIC in my PC solve my problem?  Has anyone out
there had a similar problem?  Is is fixable?  If I really have a software
problem, is there a patch? 

Please reply by email to the poster.  He will forward it to me by snail
mail, since I'm not back on USENET yet.  Thanks.

      Jeff Hallman
      Research Department
      Federal Reserve Bank of Cleveland
      P.O. Box 6387
      Cleveland, OH  44101
      (216) 579 - 3001
      Fax (216) 579 - 3050