When would a v.35 cable be used?

mitchtinmitchtin Member Posts: 20 ■□□□□□□□□□

Sorry to ask such a basic question but I am wondering when a v.35 cable would be used? this came up in a practice question I encountered recently, if I recall correctly the answer was that a v.35 cable was plugged in between two routers and this was the reason they could not communicate.



  • clarsonclarson Member Posts: 903 ■■■■□□□□□□
    The v.35 is the connector type at one end of a dte/dce cable. one end of such a cable would connect to your router and the other (the v.35 end) would plug into the communications equipment providers equipment. I've never seen a wic that had a v.35 connector on it. So, you cant use a v.35 cable to connect directly between two routers. You'd use the v.35 cable to plug into a csu that is attached to the wall.
  • theodoxatheodoxa Member Posts: 1,340 ■■■■□□□□□□
    Serial WICs typically have a DB60 (WIC-1T, NM-4T, NM-8A/S) or Smart Serial (WIC-2T) connector. You can typically purchase a cable that uses a combination of DB60 and/or Smart Serial and designed to directly connect two routers. These are basically crossover serial cables. There are also cables that have a V.35 connector on one end. These are not complete cables (for purposes of connecting two routers) by themselves, but are intended to connect to a CSU/DSU, which would in turn connect to a T1 line. Nowadays, you can buy HWICs or WICs with a CSU/DSU built right in, so they (along with external CSU/DSUs) aren't really needed anymore.

    Think of a CSU/DSU like a modem. At one time, they were external also and you would connect them to a PC with a Serial cable, and then connect the modem to the phone line. Later, folks started placing the modems inside the PC and you now only needed to connect the phone line to the back of the PC - no more serial cable and external modem. It worked the same way with CSU/DSUs, except substitute a T1 line for the phone line.
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  • james43026james43026 Member Posts: 303 ■■□□□□□□□□
    I agree with the other posters here. Also you aren't going to see a lot of serial connections in the field. Most dedicated WAN technologies that used serial cables in the past to interface with your equipment, has gone away, even a T1 line would use a smartjack and a RJ48 interface, nowadays.
  • mitchtinmitchtin Member Posts: 20 ■□□□□□□□□□
    OK thanks, that seems to make sense
  • dontstopdontstop Member Posts: 579 ■■■■□□□□□□
    So let me get this straight.

    When using something like a DTE v.35 cable, we have essentially a straight through cable for connecting DTE (The Router) to a DCE (CSU/DSU)

    When using a DCE v.35 cable we have essentially a crossover cable for connecting the Router to something that doesn't provide clocking itself (so we're able to connect thanks to the crossover and provide the clocking) and we require the crossover due to the devices having a similar pinout being both DTE.

    And a DCE/DTE cable or a piggy backed v.35 DCE+DTE are used for when we want to connect devices together using similar interfaces like DB60 or Smart Serial with cables we already have.
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