Slow transfer with 21140 card

[Frank Sweetser]

==> Regarding Re: Slow transfer with 21140 card; Mark Hahn <hahn@neurocog.lrdc.pitt.edu> adds:

>> I just found that UDP appears to be transmitting correctly, whereas TCP
>> is slow.  Thanks to Mark Hahn for the suggestion.  Now what does this
>> mean and what do I do?

hahn> when this happened to me, the cause was somewhat embarassing.  I had
hahn> wired the cables/connectors myself, using good cat5, not abusing the
hahn> cable, testing the crimp, etc.  unfortunately, I had assumed that
hahn> RJ45's were wired with pairs on adjacent pins (ie,
hahn> orange-white,orange,grn-wh,grn,blu-wh,blu,brn-w,brn).  unfortunately,
hahn> it's not sane like this: the green pair is split, and the reversed
hahn> blue pair is in between.  the result was that my Tx signal pair (I
hahn> think) was now on wires in two pairs, that is, not twisted.
hahn> obviously, this is very lossy, and I was surprised that it ever
hahn> worked.  note also that it worked pretty well at 10bT, as well...

from what i've heard, it was done this way to acomodate data and phones
over the same lines.  phones already used the center pair, so that was left
alone, and the others were wired around it.

-- 
Frank Sweetser rasmusin at wpi.edu fsweetser at blee.net | PGP key available
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