Question about Ethernet

Discussion in 'OT Technology' started by 04, Jan 11, 2003.

  1. 04

    04 Guest

    At my work, we have many laptops. I use one myself, but I noticed something very odd when looking at the Ethernet port on mine. It had only 3 conductors! :ugh: Yet when plugged in, worked perfectly with a 100baseTX connection! :wtf: How does this work? A category 5 cable has 4 pairs, or 8 wires. How can the laptop still get a 100mbit connection with only 3??? My boss said that TCP/IP only uses 3 of the wires, but that makes no sense to me. Anyone know? :confused:
     
  2. Rob

    Rob OT Supporter

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    Uhm, are you sure that weren't 4 connectors? Ethernet should 4 connections, RX+,RX-,TX+,TX-.

    TCP/IP is above ethernet in terms of the OSI model so that wouldn't have anything to do with it.
     
  3. 04

    04 Guest

    Yup, I am positive it was only 3.
     
  4. Dommi

    Dommi Guest

    cat 3 is 1 pair... wires 1 and 3 IIRC
    cat 5 is 2 pair... wires 1, 3, 5, 8 IIRC
    cat 5e is 4 pair... all wires used

    3 wire ethernet.
    :dunno:
     
  5. 04

    04 Guest

    Cat 5e supports 1gbit operation right? Gigabit over copper? So what the heck is Cat 6 for then? :confused:
     
  6. Dommi

    Dommi Guest

    cat 6 isnt a standard as of yet
    cat 5 e is regular cat with 4 pair cabling that is rated at 350 mhz. IE the twists are tighter

    cat 6 is further enhanced cable. a new design
     
  7. 04

    04 Guest

    Oh. Well, I would assume that cat 6 just has tighter twists than 5e then?

    Do you have any website links about cat 6 by any chance?

    Thanks! :)
     
  8. Dommi

    Dommi Guest

  9. mdaniel

    mdaniel S is for Shiksa

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    Uh, no. There's no such thing as "Ethernet cable". CATx are multipurpose cabling standards and Ethernet is just one application for it.

    Cat3 is 4 pair rated up to something like 16Mhz. Since Ethernet (the old 10Bbit kind) runs at 10Mhz, it can run over Cat3. Ethernet only uses two of the pairs. 1,2,3,6

    Cat5 is 4 pair rated for 100Mhz. Since Fast Ethernet only runs at 33Mz, it runs fine on Cat5. Just like Ethernet, Fast Ethernet only uses two pairs. 1,2,3,6. Gigabit Ethernet also runs over Cat5, but it requires all 4 pairs.
     
  10. mdaniel

    mdaniel S is for Shiksa

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    Remember that these are multipurpose cabling systems designed to be used for many years. The idea is to have cabling that can continue to be used as new technology is developed to run over it. Businesses don't want to have to recable their buildings every time a slightly faster tech comes along.
     
  11. Dommi

    Dommi Guest

    ethernet is a signaling standard based around multiple broadcasts over a single set of cables

    cat x cabling is just an implementation of that standard
    I stand by my words though
    cat 3 is 1 pair
    cat 5 is 2 pair
    cat 5e is 4 pair
    and yes, cat 5 cable is generally synonimous with ethernet cable
    :rolleyes:
     
  12. mdaniel

    mdaniel S is for Shiksa

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    Jesus, you're igornant. You might want to pick up a book on LAN cabling or at least do a google search before shooting your mouth off. They're ALL 4 pair cabling systems and various OSI Layer 2 applications other than Ethernet run over them. Ethernet is the most common use for Cat5 today, but its far from the only one.

    Cat3- http://www.networkstuff.net/Category_What/Category3.htm

    Cat5-
    http://www.networkstuff.net/Category_What/Category5.htm

    Cat5e- http://www.networkstuff.net/Category_What/Category5E.htm
     
  13. Dommi

    Dommi Guest

    hey man believe what you want to. Im not about to scour the fucking web for depricated spec sheets on cat 3 cabling. But Ill leave you with this. The recommended configuration is that of a 4 pair setup. There is only one needed pair in cat 3. 2 in cat five. Take your head out of your ass and do your own search. Because I know what Im talking about but do you...
     
  14. mdaniel

    mdaniel S is for Shiksa

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    Ethernet requires 2 of the 4 pairs of Cat3. Fast Ethernet requires 2 of the 4 pairs of Cat5. Don't confuse Ethernet with cabling standards! Ethernet may only use two of the pairs, but other networking systems may use 3 or 4. That's why the cabling is called multipurpose. There is nothing "recommended" about 4 pairs. If it isn't 4 pair, pinned properly, it is NOT Cat3 or 5. It will still work for Ethernet even if pins 4,5,7,8 are wired wrong or missing, but its NOT Cat3/5. It will FAIL a CA3/5 tester.
     
  15. Dommi

    Dommi Guest

  16. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    You know I still don't get how he's getting a 100BaseT connection using three wires.

    He's right - CAT X has nothing to do with the number of wires a cable has, it's simply a spec rating of the cable. Different Ethernet specs require different minumum Cat levels. For example Cat 3 is primarily used in telecom, but can come in anything from single pair to 100 pair.
     
  17. fuzzynaval

    fuzzynaval Enlighten me

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    MDaniel, you need to chill with trying to prove your knowledge. People call it ethernet cable, because most places that sell cables, write on the packaging "ETHERNET CABLE" So it's easier for people to identify what they would need that cable for. Don't be such a pompous ass about it.
     
  18. Mikel

    Mikel .

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    Cat-5 into a token-ring MAU fockers! :fawk:

    [​IMG]

    I'm still waiting for our resident layer-1 specialist, datacom guy to chime in here with the real scoop. All I know is that there was some debate as to how to deliver power over ethernet due to one of the pairs not always being punched down in many wiring closets.
     
  19. tenchuninja

    tenchuninja Guest

    :rofl: at the mouse. rat's nest?
     
  20. Rob

    Rob OT Supporter

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    Token-ring :ugh:
     
  21. mdaniel

    mdaniel S is for Shiksa

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    That's marketing. Reminds me of Compaq selling "Internet PC's". Pretty meaningless. I get pissed when people shoot their mouths off and spew out stuff that's false. No wonder so many people are so confused about computers. There's so much misinformation out there. I found those links in about 5 seconds on Google. Not hard to do.
     
  22. Mikel

    Mikel .

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    Afraid of a little bit-swapping girlie man? :fawk:


    [​IMG]
     
  23. Rob

    Rob OT Supporter

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    :rofl: :rofl: :rofl:
     
  24. Rob

    Rob OT Supporter

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    :squint:

    Am I talking to the sheep humper or Mikel here?
     
  25. Dommi

    Dommi Guest

    fyi I learned that in a networking class
    :dunno:
    guess the school had false curriculm
     

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