I'm running an Ethernet cable in the walls from the wireless router
to the church office. (everything else is wireless, but one
computer needs a wired connection.) I'll be terminating the cable
with 8P8C modular keystone jacks. Am I supposed to use 568A or 568B
The more I read about it, the confuseder I get; I know for a
straight-through cable the colors don't really matter electrically
(as long as I pair them correctly) but I don't want to make a mess
for the next guy that wants to add on, or has to replace the cable.
It kind of looks like male-to-male cables are traditionally wired A
and female-to-female are wired B. ???
Ethernet with work in any combination 568A or B but just in case you end
up using those cables for something else in the future, stick with one
particular pinout for all cable ends for the whole facility. Which exact
one will depend on what you MAY use those cables in the future. 568A may
be more convenient if you may use those cables for phones, 568B - for data
Patch cords can be wired either A or B as long as they have the same
pinout on both ends.
It's one of the things I do for money. All of the network cabling I
install and all of that installed by the other guys I know is 568B.
Patch cables will often follow the 568A pattern but it doesn't matter
because they're the same on both ends unless you run across a critter
known as a "crossover cable". The difference between 568A and 568B
wiring is that the green and orange pair positions are reversed.
You can use either but they must be the same on both ends.
Also depends on local telecommunication codes. Both are 8 wire UTP
so it doesn't really matter if 586A starts out with W/green and 586B
starts with W/orange as long as it's punched down the same way on each
end. And same with cables. Just make sure both ends are either 586A or
586B. Digital signals could care less about what color they ride
It is true but the (anecdotal) reason for that is so archaic it's not even
funny: it was instilled by AT&T back in the early 80s so people would not
take digital phones from work (B) and plug them into home phone outlets (A
or, more likely, RJ). A ring signal from an analog phone line would kill a
digital phone. None of that matters anymore, so the OP would be fine with
either A or B.
Well, again, if he ever to re-purpose the cables for phones (you never
know, cables survive for so long that there may be a need 10 year later),
568A would make it a bit easier to use one cable for two or more parallel
For the first ethernet cables I made, I didn't pay attention to
pairing. They worked OK for 10mbps, but when I when to 100mbps the
connect lights came on but there was no data connection.
Be sure to wire both ends of the cable the same.
That is a good point Mark. As the data rate goes up, you have to watch
your pairings. I bet your 10 mb LAN was failing about 50% of the time
but it would connect, just slowly. I saw a farmer running AS/400 (1 mb
twinax protocol) down a barbed wire fence, just to prove a point but
it was slow.
The church has a 66 punchdown block for the phones (I put that in
last week) but not for the Ethernet.
The jacks have 110 punchdown terminals, and they are labeled for
both A & B but the labels don't make any sense. I'm gonna have to
use a continuity tester and figure out the pin-out (I think it's
1234 down one side and 8765 on the other, where the outermost
terminals are 4 and 5) I may do that tonight.
I've about decided to use B. If the jack is wired the way I think it
is, the orange pair (for B) goes on the inner left and the brown
pair on the right, then the green pair gets separated left and right
in the next terminals, then blue in the outermost terminals. To
wire it "A", just swap the orange and green.
If I was evil, I would put a crossover cable in the walls. ;-)
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