Hi Gustav,
Re; established standards, sure. First the key is not the wire color,
while that's more a less a standard, there are certainly cables using
different trace colors than the ones I provided. The real issue is
pinouts, and how they are interconnected. Each end of connection has a
transmitter and a reciever. One uses pins 1 & 2, the other uses pins 3 &
6. Transmitters must connect to recievers and visa versa. So, if you were
to connect two NIC to each other pins 1 & 2 on NIC A would have to connect
to pins 3 & 6 of NIC B, and pins 3 & 6 of NIC A would connect to pins 1 & 2
of NIC B.
There are cables connected exactly like this.
NIC A
NIC B
1 ---------------------------------------------- 3
Xmitter {
}Rcvr.
2 ---------------------------------------------- 6
3 --------------------------------------------- 1
Rcvr. {
} Xmitter.
6 ---------------------------------------------- 2
However:
Rather than use crossover cables as shown above, the convention is for NICs
to be wired as shown and Hub to be reversed: ala'
NIC
HUB
1 ---------------------------------------------- 1
Xmitter {
}Rcvr.
2 ---------------------------------------------- 2
3 --------------------------------------------- 3
Rcvr. {
} Xmitter.
6 ---------------------------------------------- 6
The connections between a Transmitter must be "balanced". Balence is
provided by twisting the two wires so that each wire in the pair picks up
"approximately" the same amout of ambient electrical noise from the
environment. That way the noise arriving at a the reciever, know as the
Common Mode Signal can be rejected, and only the "real" signal is received.
So you need two pairs of wires. A second benefit of twisting the wires is
that the impedence of the pair is controlled, about 100 ohms in CAT5. By
matching the output impedence of the transmitter to the cable and the input
impedance of the cable to the receiver, the deliverery of signal power from
transmitter to receiver is maximized.
The signal is without polarity, so while it might seem that pin 1, of a
pair, should go to pin 2 on the opposite end and pin 2 to pin 1, this is
not neccessary and allows cables to be wires "straight through. 1 to 1, 2
to 2, 3 to 3 and so on.
You may find some networks wired with two pair cable, it's cheaper than 4
pair CAT5. It works, but it does violate the media standard for Eithernet,
(802.3).
You may also find systems wired using the telecommunications (telephone)
industry color codes, (EIA/TIA-568).
Pair 1 Tip White/blue
Ring Blue
Pair 2 Tip White/orange
Ring Orange
Pair 3 Tip White/green
Ring Green
Pair 4 Tip White/Brown
Ring Brown
This will also work fine, just ensure that you have pairs between pin sets
and are using appropriatly certified wire for thespeed at which you want
the circuit to operate. Buy CAT5, and you will be doing that. In other
words don't accept UTP-3, UTP-4, UTP-5, or STP-5.
Of course, while installing the cables, you will want to ensure you do not
exceed the "recommend" pull force of 110 Newtons, per standard SP 2840A.
Please recognize 110 Newtons (about 25 foot pounds) is only a
recommendation as it has not yet be accepted as a "standard". :<))
Hope this helps,
Tom
Gustav Schaffter <[EMAIL PROTECTED]>@redhat.com on 10/07/2000 11:07:55
AM
Please respond to [EMAIL PROTECTED]
Sent by: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
cc:
Subject: Re: Network cabling
Tom,
I have been doing my own cables for a while. My primary reason is that I
get them in the lengths that I prefer. I don't need to use a twenty feet
cable where a twelve feet cable would do.
I have always been following the instructions in a users guide I
received when I bought a hub from Linksys. That's so far been my only
reference.
I noticed that in the guide I have, they have inverted the use of pins 4
and 5 compared to your explication. This shouldn't be of any importance
as long as I'm consistent.
But can you confirm that your explanation adheres to established
standards and that there is a bug in the Linksys guide?
Regards
Gustav
[EMAIL PROTECTED] wrote:
>
> What are we talking about, installing a networkk, or making cables?
Making
> cables is a waste of time, you can buy 10' cables with RJ45s on each end
> for less than three bucks. If you are talking about stringing CAT5 thru
> walls and ceilings, a book won't help a lot. What you need is a roll of
> cable, a 24" long 3/8" drill bit, and a step ladder. Or you can call an
> electrician and tell her/him where you want the wires to terminate.
>
> The electrician can also put the connectors on. But if you want to do
that
> yourself put OG/WT on pin 1, OG on pin 2, GN/WT on pin 3, BU/WT on pin 4,
> BU on pin 5, GN on pin 6, BN/WT on pin 7, BN on pin 8. You can buy a
tool
> for installing the RJ45 connectors for about $22.00. The wall plates
have
> punch down strips in them, tool about $3.00
>
> Have fun!
>
> Tom
>
> Bret Hughes <[EMAIL PROTECTED]>@redhat.com on 10/06/2000 12:46:19 PM
>
> Please respond to [EMAIL PROTECTED]
>
> Sent by: [EMAIL PROTECTED]
>
> To: [EMAIL PROTECTED]
> cc:
> Subject: Re: Network cabling
>
> Frank Reichenbacher wrote:
>
> > Anybody know a good site or book for do-it-yourself twisted pair
cabling
> > written for nitwits like me? I cannot wire a clip to save my life.
> >
> > Frank Reichenbacher
> >
>
> There are probably real books, but I learned the little that I know from
> talking with an eletronics distributor and getting some catalogs from him
> that have LOTS of info in them about various wireing configs. I don't
have
> them at hand right now but seems like the Black Box catalog also has some
> stuff in it. The ethernet howto has wiring diagrams for common ehternet
> scenarios, including a crossover ethernet cable.
>
> HTH
>
> Bret
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