RE: [UUG/MLUG] Various networking questions:

["Buford, Rick" <EMAIL:PROTECTED>]

As many times in the recent past as this question has been asked, I was
thinking about trying to do a real simple page with some decent diagrams so
we could simply refer people to it rather than explaining it each time. Do
you mind if I plagarize you so I don't have to re-write it again?

Rick Buford
Chief Clerk
Medical Records - Transcription
DC042.06 / 884-7452
"A bus station is where a bus stops. A train station is where a train
stops. On my desk I have a workstation...."


   |-----Original Message-----
   |From: McNutt, Justin M. [mailto:EMAIL:PROTECTED]
   |Sent: Sunday, November 28, 1999 2:00 PM
   |To: EMAIL:PROTECTED
   |Subject: [UUG/MLUG] Various networking questions:
   |
   |
   |There have been various networking/cabling questions on 
   |here lately.  Here
   |are some of the answers, answered ad nauseum <grin>:
   |
   |1)  There are several kinds of Ethernet over CAT5.  One is 
   |10BASE-T, which
   |uses pairs 1-2, and 3-6.  Another is 100BASE-TX which is 
   |100Mb and uses the
   |same four wires as 10BASE-T.  Another is 100BASE-T4 which 
   |uses all four
   |pairs in CAT5, and the last is 100BASE-T2, which uses the 
   |same four wires as
   |10BASE-T, but can be used with CAT3 cabling (lower quality).
   |
   |Only 10BASE-T, 100BASE-TX, and 100BASE-T4 can use autonegotiation.
   |100BASE-T2 has no standard for that yet.  10BASE-T and 
   |100BASE-TX are the
   |most common and use only four of the eight wires available 
   |in standard CAT5.
   |
   |2)  If you are going to wire your house, use plenum cable 
   |(has to do with
   |the coating - not the shielding - and fire regulations), 
   |and keep it well
   |away from power lines.  The three feet mentioned before for 
   |unshielded
   |cabling sounds about right.
   |
   |3)  You can use any single pair of CAT5 for a phone line, 
   |for up to three
   |lines in a jack (RJ11 jacks have only six leads).  This is 
   |a good idea since
   |the twisting in CAT5 gives you better signal quality for 
   |your local loop
   |(the wiring in your house).
   |
   |4)  You can *try* running 10BASE-T or 100BASE-TX over four 
   |of the wires in a
   |CAT5 cable, and running phones over one or both of the 
   |other pairs.  As long
   |as the jacks are a bit apart, I can't see that there would 
   |be much of a
   |problem, since they use such vastly different frequencies.  
   |Remember that
   |even a 28.8kbps modem is actually running at 2400 *baud*, 
   |but uses phase
   |modulation to transmit many bits per baud.  So you have the 
   |modem at 2400Hz
   |and the network at 125MHz (100Mb Ethernet).  The signal 
   |filters in each set
   |of devices should keep out the noise (if any) from the other.
   |
   |Of course, that's theory.  It *should* work, but you'll 
   |have to try it.
   |
   |5)  All you have to do to hook two Ethernet computers 
   |together is make (or
   |buy) a crossover cable.  They can be purchased 
   |commercially, you just have
   |to ask for them sometimes.
   |
   |Here's the instructions for making your own Ethernet 
   |crossover cable (this
   |is long):
   |
   |You need a CAT5 patch cord, a crimper with an RJ45 die, and 
   |the appropriate
   |RJ45 tips.  Pay attention to the type of cable you have 
   |because there are
   |different tips for solid cable and stranded cable (is the 
   |copper wire a
   |single solid wire or a lot of little wires?).  Make sure 
   |you have the right
   |die for the tips you're using.  For computer-to-computer, 
   |stranded cable is
   |recommended.
   |
   |Those parts are available from catalogs, and probably from 
   |Insight.com if
   |you poke around a bit.
   |
   |For 10BASE-T or 100BASE-TX, look at one end of the cable.  
   |Write down the
   |colors of the wires *in order* as you see them.  Here's an example:
   |
   |Pin 1:  Orange
   |PIn 2:  White-Orange
   |Pin 3:  Blue
   |Pin 4:  White-Green
   |Pin 5:  Green
   |Pin 6:  White-Blue
   |Pin 7:  Brown
   |Pin 8:  White-Brown
   |
   |Note that 3 and 6 are a pair and 4 and 5 are a pair.  They 
   |don't just go
   |1-2, 3-4, 5-6...
   |
   |Anyway, chop off the connector at the other end.  Then, 
   |using the example
   |colors above (you'll have to modify these instructions for 
   |your cables), you
   |would insert the wires at the other end into one of the 
   |RJ45 tips in this
   |order:
   |
   |Pin 1:  Blue
   |Pin 2:  White-Blue
   |Pin 3:  Orange
   |Pin 4:  White-Green
   |Pin 5:  Green
   |Pin 6:  White Orange
   |Pin 7:  Brown
   |Pin 8:  White-Brown
   |
   |Note that *pair* 1-2 gets swapped with *pair* 3-6.  Now the 
   |transmit pair on
   |one side goes to the receive pair on the other side, and 
   |vice versa.  This
   |is because usually you have a concentrator (or switch) do 
   |this for you, but
   |since you're going to plug directly into the interface at 
   |the other side,
   |you have to swap the wires yourself.
   |
   |Anyway, make sure you untwist the wires as little as 
   |possible getting them
   |into the RJ45 tip, and crimp it with the crimper.  Then try it out!
   |
   |To make a Token Ring crossover, it's pretty much the same 
   |thing, but you
   |have to crossover pairs 3-6 and 4-5 instead.  I don't know 
   |about 100BASE-T4,
   |and I don't think you *can* crossover 1000BASE-T (Gb).  
   |100BASE-2 should be
   |the same as 100BASE-TX.  I have the specs on all of those 
   |somewhere if
   |somebody's really interested.  <grin>.
   |
   |Clear as mud?  Hope some of that helps!
   |
   |--J
   |