OT: network cable troubles

[JohnV@nn]

Sorry to ask such a blatantly off-topic question here. I needed to make a 65-foot patch cable for temporary use, so I got a reel
of Cat-5e cable and some RJ-45 plugs, and borrowed a crimper. I cut a 65-foot length and crimped on the plugs. But the cable
didn't work. The PC could not ping the router. I re-did the plugs, and it still didn't work.

I thought there must be a problem somewhere in that piece of cable, so I pulled off another 65-foot piece and put ends on it.
Same thing; cannot ping the router. (So now I have two bad 65-foot patch cables). As a sanity check, I made a short (5-foot)
cable, and it works perfectly.

Where am I going wrong with these 65 footers? I have taken a continuity tester and verified that there is continuity on all 8
pins. The PC indicates "Local area network is now connected" when I plug the cable in, and the little task bar icon shows a
little bit of activity. But it cannot get an IP address from my router. If I switch to a known good cable, it gets an IP address
within 2 seconds.

Admittedly, this is my first attempt at making a patch cable. I was very discouraged until I made a 5-foot cable that worked.

Bummed,
John

 

[daytripper]

Sorry to ask such a blatantly off-topic question here. I needed to make a 65-foot patch cable for temporary use, so I got a reel
of Cat-5e cable and some RJ-45 plugs, and borrowed a crimper. I cut a 65-foot length and crimped on the plugs. But the cable
didn't work. The PC could not ping the router. I re-did the plugs, and it still didn't work.

I thought there must be a problem somewhere in that piece of cable, so I pulled off another 65-foot piece and put ends on it.
Same thing; cannot ping the router. (So now I have two bad 65-foot patch cables). As a sanity check, I made a short (5-foot)
cable, and it works perfectly.

Where am I going wrong with these 65 footers? I have taken a continuity tester and verified that there is continuity on all 8
pins. The PC indicates "Local area network is now connected" when I plug the cable in, and the little task bar icon shows a
little bit of activity. But it cannot get an IP address from my router. If I switch to a known good cable, it gets an IP address
within 2 seconds.

Admittedly, this is my first attempt at making a patch cable. I was very discouraged until I made a 5-foot cable that worked.

Bummed,
John

CAT Ethernet cable is comprised of four twisted pairs. If you don't wire the
connectors correctly, you'll have the two legs of differential pairs traveling
on different wire pairs. Not good - as you have discovered.

Follow one of the two wiring standards at both ends and you should be good to
go.

http://www.duxcw.com/digest/Howto/network/cable/cable5.htm

/daytripper

 

[JohnV@nn]

Thanks for the reply. I wired both ends exactly the same (Orange, Blue, Green, Brown) and I made doubly sure of this when I cut
off the ends and re-did them. I even used a continuity tester to made sure that pin 1 was going to pin 1, pin 2 to pin 2, etc.

 

[Ian]

A common mistake for beginners is to invert the jacks so you have the wires
in the opposite orientation at one end.
Check that both ends are identical when the holding clip is face-down.
Also make sure each wire is forced to the ends of the channels before
crimping.
I always check both ends with a lupe before I squeeze the trigger!
The quality of the jacks makes a difference too. Out of a bag of 25
cheapies, usually 2-3 are no good.
There are also differnet jacks for solid or stranded CAT5 cables, but if
you're carefull, they can be interchanged.

You should be good for up to 350 feet or so, so your 65 footer is well
within range.

I.M.

 

[Michael W. Ryder]

Sorry to ask such a blatantly off-topic question here. I needed to make a 65-foot patch cable for temporary use, so I got a reel
of Cat-5e cable and some RJ-45 plugs, and borrowed a crimper. I cut a 65-foot length and crimped on the plugs. But the cable
didn't work. The PC could not ping the router. I re-did the plugs, and it still didn't work.

I thought there must be a problem somewhere in that piece of cable, so I pulled off another 65-foot piece and put ends on it.
Same thing; cannot ping the router. (So now I have two bad 65-foot patch cables). As a sanity check, I made a short (5-foot)
cable, and it works perfectly.

Where am I going wrong with these 65 footers? I have taken a continuity tester and verified that there is continuity on all 8
pins. The PC indicates "Local area network is now connected" when I plug the cable in, and the little task bar icon shows a
little bit of activity. But it cannot get an IP address from my router. If I switch to a known good cable, it gets an IP address
within 2 seconds.

Admittedly, this is my first attempt at making a patch cable. I was very discouraged until I made a 5-foot cable that worked.

Bummed,
John

Just out of curiosity have you tried a different brand of network card?
I recently spent a full day trying to get a 200' cable to work. Redid
the ends, tested, etc. Finally out of frustration I put in a different
network card and everything worked perfectly.

 

[Donald Witmer]

Just out of curiosity have you tried a different brand of network card? I
recently spent a full day trying to get a 200' cable to work. Redid the
ends, tested, etc. Finally out of frustration I put in a different
network card and everything worked perfectly.

You should use an ethernet cable tester. I once went on a service call and
the operators told me the computers would work some times and other time not
communicate. I used a cat 5 ethernet cable tester and after checking I found
none of his patch cords would pass when I plugged them (test fails when
testing a short patch cord) and tested but continuity was good. Found
someone in the office wanted to save some money and made their own using a
meter. Crossed pairs. A short jumper may work with crossed pairs but in 65
feet I do not think it will work.

Joltjocky

 

[Michael W. Ryder]

You should use an ethernet cable tester. I once went on a service call and
the operators told me the computers would work some times and other time not
communicate. I used a cat 5 ethernet cable tester and after checking I found
none of his patch cords would pass when I plugged them (test fails when
testing a short patch cord) and tested but continuity was good. Found
someone in the office wanted to save some money and made their own using a
meter. Crossed pairs. A short jumper may work with crossed pairs but in 65
feet I do not think it will work.

Joltjocky

In my case we did use an Ethernet cable tester. We were connecting a
computer to a ISP in the same building and I was working with two of
their employees. For some reason the original NIC did not get along
with their switch.

 

[daytripper]

Thanks for the reply. I wired both ends exactly the same (Orange, Blue, Green, Brown) and I made doubly sure of this when I cut
off the ends and re-did them. I even used a continuity tester to made sure that pin 1 was going to pin 1, pin 2 to pin 2, etc.

I'll say it again: you have swapped pairs.

You cannot make a fully functional ethernet cable by simply sticking arbitrary
colors on the same pins at both ends. That will give you continuity - and a
bad cable.

Try reading the fricken' link this time...

/daytripper

 

[Paul]

Thanks for the reply. I wired both ends exactly the same (Orange, Blue, Green, Brown) and I made doubly sure of this when I cut
off the ends and re-did them. I even used a continuity tester to made

[/QUOTE]
sure that pin 1 was going to pin 1, pin 2 to pin 2, etc.

I'll say it again: you have swapped pairs.

You cannot make a fully functional ethernet cable by simply sticking arbitrary
colors on the same pins at both ends. That will give you continuity - and a
bad cable.

Try reading the fricken' link this time...

/daytripper

http://www.duxcw.com/digest/Howto/network/cable/cable5.htm

The TX+/TX- signals are supposed to travel on a twisted pair
of wires. Same with the RX+/RX-.

TX+ --\ /\ /-- RX+
x x
TX- --/ \/ \-- RX-

RX+ --\ /\ /-- TX+
x x
RX- --/ \/ \-- TX-

The reason for that, is the signals are differential, and
if the wires in a pair pick up noise, the noise cancels
when it hits the coupling transformer at the end of the
line. If you choose a wiring like this

TX+ --\ /\ /-- RX+
x x
--/ \/ \--

--\ /\ /--
x x
TX- --/ \/ \-- RX-

the noise environment of the two wires is not going to be
the same. On a long cable, there is more noise pickup, and
it won't work. (Not to mention the crosstalk from the
adjacent wires, which I didn't label in the figure above,
to make the concept of pairing clearer.)

Try to follow the assembly instructions _exactly_ and I bet
you will be pleasantly surprised.

Also, notice the color scheme. The wires that are twisted
together have alternating colors. I.e. wire 1 and wire 2
are WHT/ORG and ORG/WHT, implying they are paired.

The last page of this document, shows that even the unused
wires get wired up. On page 31, you can see the unused wires
are terminated with 75 ohm resistors - the purpose of this
is to "drain" noise from the unused wires.

http://www.intel.com/design/network/applnots/71821301.pdf

To see what is inside the transformers at the end of the
line, there is some info here:

http://www.pulseeng.com/products/datasheet.aspx?Datasheet_Id=40&idl=Y

The common mode choke (in series with the line) helps to
remove common noises seen on both wires in a pair. The
transformer takes the difference between the two signals
in a pair, and since the signals have the opposite polarity,
the difference has twice the amplitude of either signal
by itself. The transformer then delivers it to the chip.
The transformer also provides DC isolation, and notice how
there is no DC path to ground on those eight wires inside
the Ethernet cable. A capacitor with a 2KV rating is there
to couple AC noise to ground.

The differential pairs are treated as transmission lines,
and the resistors control reflections from the end of the
line. So, not only must the wires in a pair be twisted, but
they also have a certain characteristic impedance. That
means the Ethernet might not work, if you substituted
you own home made zip cord or 300 ohm TV antenna wire, in
place of a twisted pair.

So, have some respect for all the engineering that went into
that cable. The cable wasn't just thrown together, and it
will work if you follow the instructions exactly.

Paul

 

[PB]

Here is a link I have to offer:

http://www.linksys.com/faqs/default.asp?fqid=20

PB

 

[JohnV@nn]

My apologies, I must admit that I did not read your link carefully enough before. I followed the diagram as shown in your link,
and my cable now works perfectly. Previously, I did a quick web search for a diagram and picked one at random; unfortunately, the
diagram it showed was wrong. Your link set me straight. Thanks so much, daytripper!

John

 

[notritenoteri]

just a comment. MAking cable up unless absolutely necessary is not the best
option. THe crimping and de-twisting of the individual wires is critical
especially on longer cables. They are practically free to buy and you have
to make a lot of cables to save the price of a good crimper.
you decide.
: My apologies, I must admit that I did not read your link carefully enough
before. I followed the diagram as shown in your link,
: and my cable now works perfectly. Previously, I did a quick web search
for a diagram and picked one at random; unfortunately, the
: diagram it showed was wrong. Your link set me straight. Thanks so much,
daytripper!
:
: John
:
:
: >
: >>> On Fri, 20 May 2005 00:39:38 GMT, "JohnV@nn" <[email protected]>
wrote:
: >>>
: >>>>Sorry to ask such a blatantly off-topic question here. I needed to
make a 65-foot patch cable for temporary use, so I got a
: >>>>reel
: >>>>of Cat-5e cable and some RJ-45 plugs, and borrowed a crimper. I cut a
65-foot length and crimped on the plugs. But the cable
: >>>>didn't work. The PC could not ping the router. I re-did the plugs,
and it still didn't work.
: >>>>
: >>>>I thought there must be a problem somewhere in that piece of cable, so
I pulled off another 65-foot piece and put ends on it.
: >>>>Same thing; cannot ping the router. (So now I have two bad 65-foot
patch cables). As a sanity check, I made a short (5-foot)
: >>>>cable, and it works perfectly.
: >>>>
: >>>>Where am I going wrong with these 65 footers? I have taken a
continuity tester and verified that there is continuity on all 8
: >>>>pins. The PC indicates "Local area network is now connected" when I
plug the cable in, and the little task bar icon shows a
: >>>>little bit of activity. But it cannot get an IP address from my
router. If I switch to a known good cable, it gets an IP
: >>>>address
: >>>>within 2 seconds.
: >>>>
: >>>>Admittedly, this is my first attempt at making a patch cable. I was
very discouraged until I made a 5-foot cable that worked.
: >>>>
: >>>>Bummed,
: >>>>John
: >>>>
: >>>
: >>> CAT Ethernet cable is comprised of four twisted pairs. If you don't
wire the
: >>> connectors correctly, you'll have the two legs of differential pairs
traveling
: >>> on different wire pairs. Not good - as you have discovered.
: >>>
: >>> Follow one of the two wiring standards at both ends and you should be
good to
: >>> go.
: >>>
: >>> http://www.duxcw.com/digest/Howto/network/cable/cable5.htm
: >>>
: >>> /daytripper
: >>
: >
: >>Thanks for the reply. I wired both ends exactly the same (Orange, Blue,
Green, Brown) and I made doubly sure of this when I cut
: >>off the ends and re-did them. I even used a continuity tester to made
sure that pin 1 was going to pin 1, pin 2 to pin 2, etc.
: >
: > I'll say it again: you have swapped pairs.
: >
: > You cannot make a fully functional ethernet cable by simply sticking
arbitrary
: > colors on the same pins at both ends. That will give you continuity -
and a
: > bad cable.
: >
: > Try reading the fricken' link this time...
: >
: > /daytripper
:
: