Newsgroups: comp.dcom.lans.ethernet
Subject: Re: Ethernet card
From: Aengus Lawlor <RBYAML@rohvm1.rohmhaas.com>
Date: Wed, 23 Dec 1992 08:42:01 EST
Organization: Rohm and Haas Company

In article <msz.725076053@zen>, msz@ESD.3Com.COM (Mark Zaller) says:
>mbeyer@zamboni.NSP-SERVER1 (Mark D Beyer) writes:
>>> What's wrong with the 3c503?
>
>>I forget the exact model numbers, but I think 3COM has much better
>>adapters than the 3C503 now.  The 3c503 wasn't particularly fast.
>>I think there's a 3c507.
>>--
>
>The 3C503 is a good card with compatibility being its best asset. The 3C507 is
>an excellent server card. 3Com's best card today (and least expensive),
>especially for clients is the 3C509 (EtherLink III). It also autoconfigures
>and it is fast.

I have been having some interesting experiences with 3COM 3C503/16s and
3C509s recently.

We have a large population of PCs (386SX/16s through 486/50s), running
PathWorks 4.1 and Windows 3.1. Most of the workstations have 8-bit 3C503s
installed, with shared memory disabled. We have been using some 486/33 PCs
as OS/2 servers, and recently installed a 486/50 OS/2 server. Surprisingly,
it took longer to load Windows applications from the 486/50 server than from
the 486/33 server. Nortons SYSINFO showed that throughput to the faster
server was at least 20% better than to the 486/33 server, so something was
definitely afoot!

(Loading Extra! for Windows from the 486/33 server to a 386sx/16 PC took
40 seconds, with a 3C503 in the PC. It took 80 seconds to load from the
486/50).

On a hunch, I ran the 486/50 in "slow" mode, and Nortons SYSINFO showed
throughput down to about 80% of the figure for the 486/33, but the PC now
loaded Extra! for Windows in 40 seconds!

I decided that the server was serving the data so fast that the workstation
couldn't keep up, so it dropped packets, and had to wait for a timeout and
re-transmission.

So I decided to try one of the new, fast 3C509s in my my 386SX/20, and
Extra! took between 60 and 80 seconds to load from the 486/50 server, and
about 50 seconds from the 486/33. This didn't seem right, so I got out a
brand new 3C506/16, with shared memory enabled, replaced the 3C509, and now
Extra! loaded in just under 30 seconds from the 486/50, and just over 30
from the 486/33. This was more like it, so I disabled the shared memory,
and it still loaded in just over 30 seconds from the 486/33 (as against
50 seconds using a 3C509), but it now took about 50 seconds to load from
the 486/50 server!

To top it all off, I tried to load Extra! on a 486/50 workstation, with
a 3C503/16, shared memory disabled, and it took about 18 seconds from the
486/50 server, and about 21 seconds from the 486/33 server.

Now I don't know whether the problems I saw were due to NDIS, or to PathWorks,
but in a timeslicing environment like Windows, a RAM buffer may be pretty
important, and the 3C509 may not be the card you're looking for.

If anyone has any suggestions for tuning the software (either by changing
PROTOCOL.INI parameters, or by changing PathWorks paramaters, or by
changing Windows parameters) I'd appreciate it if you let me know. If anyone
has had the opportunity to compare the 3C509 to the 3C503 on other networks
especially with Windows, I'd also be interetsed in hearing what your
impressions are. (Fast servers and relatively slow workstations, ie 386SX/16s
are most likely to highlight this situation).

>
>-Mark Zaller
Aengus
--
RBYAML@ROHMHAAS.COM                    Aengus Lawlor
RBYAML@ROHVM1.BITNET                   (who used to be ALAWLOR@DIT.IE)
"How about some of that famous Dublin wit, Barman?"
"Certainly, sir. Would that be Dry or Sparkling?"
Newsgroups: comp.dcom.lans.ethernet