slow ftp transfers

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From: bv@wjv.com (Bill Vermillion)
Subject: Re: FTP problem
References: <a0hc8o$7sd$1@fe2.cs.interbusiness.it> <Gp2BnH.6oD@wjv.com> <3C2CAF50.5040708@aplawrence.com> 
Date: Sat, 29 Dec 2001 04:16:21 GMT

In article <3C2CAF50.5040708@aplawrence.com>,
Tony Lawrence  <tony@aplawrence.com> wrote:
>Bill Vermillion wrote:

>> In article <a0hc8o$7sd$1@fe2.cs.interbusiness.it>,
>> Archetti Luciano <lucarc@provincia.brescia.it> wrote:

>>>I have UNIX SCO 5,0,5.
>>>If I make ftp from a PC the serveur UNIX I go to 1000 kb/s.
>>>If I make ftp from PC serveur UNIX I go to 50 kb/s.
>>>What could be?

>> Anyone of a dozen or more things - which could vary from the brand
>> of NIC being used, settings on the NIC, wiring, hub/switch problem,
>> and so on.

>I'm wondering if there is more to this- I get this question a LOT,
>and I give the same sort of answer you did, plus advising that any
>approprate patches be installed, but maybe there is more .. ?

A great many times that I see this in another group it boils to one
common denominator - a RealTek NIC card. On an ISP mailing list it
has been noted that the NetGear switches seem to be some of the
best for getting things set properly.  The URL I posted for Cicso
notes the problems that can occur and how to set things.  You will
also seem some recommending that all network equipment come from
one manufacturer, and I don't recall if it was the Cicso list that
mentioned this or elsewhere, but where that comes into play is that
some manufacturers add extra features so these play together
nicely, but since they are not standard items they can confuse
other devices.

The problem is most often the auto-negotiation of duplex.  The
auto-sense of speed seems to be reported to work most of the time
for most cards.  I deduce this may be because that at 10Mbit you
have a carrier going on/off, so that you have periods with no
signal on the line, but the modulation scheme in 100Mbit is such
that a carrier is always present.

The 10Mbit is basically a data stream at that rate, while the
100Mbit uses encoding similar to the multi-bit per baud we first
saw in old analog modems.  The 100Mbit carried freqency is about
33MHz and we get 3 bits on each change of state.  So you can see
that in itself - a on/off carrier or constant carrier makes
auto-sensing easier.  It's the auto negotiating that seems to be
the problem.  The ISP group seems to fell the iNTEL cards are the
most reliable in virtually all instances.

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