Re: OT:Switch boosts ethernet?

On Thu, Feb 19, 2009 at 11:21 AM, Alan Dayley <alandd@consultpros.com> wrote:
> If this were a casual situation, we might do what you suggest. But
> using a cable that is too long is known to be a source of intermittent
> and odd problems. In this situation we'd rather do it right once and
> not worry about errors happening when we least want them.
>
> This is a pretty good if not detailed explanation of the length limit:
> http://www.duxcw.com/faq/network/cablng.htm
>
> Basically, as I understand it, when the Ethernet sender ships out the
> packet it will wait for an acknowledge from the destination. The
> signals running through the cable are very, very fast but are not
> instant to the other end. When the cable is too long, the sender
> could declare a time out on the acknowledge and resend before the
> destination gets the packet. Collisions or other problems could then
> ensue. So, theoretically, it does not matter much how "good" the
> cable is because the limit is based propagation of the signals.

Also -- with long cables you get noise on the cable called cross talk
(NEXT & FEXT). The cross talk is worse on a long cable at 100Mbps or
Gigabit speeds. If you are running half duplex, you will get late
collisions on a 'too long' cable that would cause noticeable packet
loss or packet delay that will show up as frame drops in a video feed.

A switch is a really good solution. Please make sure to use Full
Duplex for the smoothest packet flows. Fiber is a good solution if you
had to go a lot further, but there are higher costs with that.

From my POV, Cat 6 and Cat 6e are just marketing terms. However, the
cost of copper cable is usually small compared to the labor costs of
installation.

P.S. In a casual situation 10Mbps/Full would probably work fine with a
good installation of Cat5e.
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