Since virtually every technical discussion I can find, simply
quotes the characteristics of the cable, it's pretty hard
to say anything definitive. I.e. "My mom says Cat 6 is better
than Cat 5, because 6 > 5."
Quoting the specs, doesn't say anything about the contributions
to signal budget, and how much "margin" is available when each
cable type is used. And I'm not seeing that kind of info.
I would say, when the cable length is short, the superior
performance of one cable versus another, will not be evident.
Only at max distance and max datarate, would any difference
become evident.
So answering the question becomes more important, if the distance from
one computer to another, approaches 100 meters (300+ feet).
Part of the impairment in cables, comes from bundling them. At
work, the staff used to build the most beautiful fat bundles
of copper wiring, under the building raised flooring. They'd
put nylon wraps every few inches, ensuring one cable was
as close to the next cable as possible. Talking to one of
the support people at work, this was not naively done, and
studies would usually be undertaken a couple years in advance,
to make sure that such installations would actually work.
In a home situation, there is no "alien" crosstalk to speak
of. (Hardly anyone has enough cables, to be bundling them
and strapping them up with nylon wraps.) So right away,
that is one less impairment than in an office building.
Ethernet cables are not shielded, with the exception of the
highest cable grade (where they seem to have added an external
shield). In such a shielded cable, there would still be crosstalk
between the pairs within the same cable, but less of an issue
if the cables were put in fat bundles.
Since I've yet to run into a situation, where my networking
connections were affected in any way by my choice of purchased
cables, in the absence of any other info, it doesn't look
like it makes much difference.
*******
If you go back far enough, you can find references to
running GbE on Cat 5 cable, so much of the fluff you
find in a search now is "specsmanship". Quinary signaling
was specified by some genius at the time, as a solution
to not radically changing the kinds of cables needed.
http://www.tmworld.com/article/321652-What_PAM5_means_to_you.php
There is a bit more of the "meat" of GbE here. Including
an eye diagram sketch for PAM-5. Apparently GbE uses
forward error correction, to improve effective noise
margin. And that helps compensate for the lower
amplitude of each "eyelet" in the PAM-5.
http://www.eetimes.com/electronics-...g-the-Challenges-of-Delivering-GigE-Over-Cat5
More basic info here.
http://en.wikipedia.org/wiki/Gigabit_Ethernet
"1000BASE-T
Each 1000BASE-T network segment can be a maximum length of
100 meters (328 feet), and must use Category 5 cable or better.
Category 5e cable or Category 6 cable may also be used."
*******
ADSL-2 rates (24Mbit/sec) don't require GbE. It can be handled with 100BT
just fine. Even the VDSL2 mentioned here, at 60Mbit/sec,
can be carried on 100BT. Maybe with some cable modem standard
(DOCSYS with bonding), you might reach a point where the
next level of networking would be required.
http://en.wikipedia.org/wiki/ADSL_2+
I use a GbE switch and GbE on a couple computers here, for
no particularly good reason. Results range from disappointing,
to sorta OK. I have to go to a lot of trouble, to get
117MB/sec transfer rates, out of a max of 125MB/sec, when on
the GbE switch. Being careless, usually nets me 3 to 20MB/sec.
ADSL --- 3Mbit/sec --- router --- 100BT --- GbE_switch --- Computer #1
(i.e 10BT) | Computer #2
| 100BT
|
Computer #3 etc
When you use a setup like that, if gives the potential for faster transfers
between computer 1 and computer 2, while computer 3 or connections to
the Internet use a lower rate. Seeing as all I've got is ADSL (not 2
or 2+) and my profile is so low (3 megabits/sec), even a 10BT connection
to the router suffices for the Internet connection.
HTH,
Paul
