What's the deal with DSL??

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  • Figment
    Gluten Enthusiast
    • Dec 2001
    • 13641

    What's the deal with DSL??

    I have a cable connection here at home. It's delightful.

    I have a dialup connection at work. It's EXCRUCIATINGLY slow. But it's all I've been able to afford or justify until now.

    I recently ordered the dialup connection upgrade to a DSL connection. Based on some flawed information gleaned from the sales rep when I first set up the dialup connection last year, I'd assumed that the phone company would need to come out and snake a new cable through the wall to execute the DSL connection. My assumption was incorrect. The "self-install" package arrived today. A little black modem-ish thing, two cables for connecting the modem-ish thing to the wall and computer, and a CD.

    So what's the deal? This thing plugs into the same phone jack that provides the dialup connection, served by the same decades-old infrastructure.
    How does DSL achieve greater speed over the same old phone system?
    If it's so easy as all that, why do "traditional" dialup connections exist at all anymore?

    (caveat: I haven't actually installed anything yet, so my comments on increased speed have no basis in experience)
    People today will buy a car with square wheels as long as the steering wheel is heated.
  • Jagermeister
    Senior Member
    • Aug 2005
    • 876

    #2
    DialUp works over any voice grade phone line, which is specified as a 4KHz bandwidth and lengths up to many miles.

    DSL uses extended spectrum far above the voice band, with a maximum length of about 20K feet (6K meters). DSL requires the removal of bridge taps (those are forks in the phone line) and filters from the phone line.

    Not all voice lines are qualified for DSL. Your line must be untapped, unfiltered, relatively close to the Central Office or DSLAM (Digital Subscriber Line Access Multiplexer).

    Also, your in-house wiring must be in relatively good shape. Excessive numbers of extensions can cause signal degradation and disrupt DSL.

    The rest is pretty boring technical specifics. Hope this answers your question.

    Comment

    • High C
      Senior Member
      • Mar 2003
      • 8984

      #3
      Fig, the phone company added a magic box of some sort to your phone line, usually outside where the phone line comes into the buiding. This box "splits", in virtual fashion, your single phone line into two, one for voice, and one for DSL. Maybe it was already there, but at some point, this work was done to your line to facilitate DSL.

      There's more to it, certainly, but that's part of why DSL costs more. It is more involved to install than a basic phone line. And it's certainly worth more.

      Also DSL only works if you're close enough to a switching station, too, something like 3 miles, IIRC. Dialup will work anywhere.

      [ 12-22-2005, 04:16 PM: Message edited by: High C ]

      Comment

      • ishmael
        Banned
        • Jun 2000
        • 23518

        #4
        And it's not availale at your humble servants homestead. I'm too far out, so to speak.

        So, now that that is covered, how much more expensive, and how much faster is a cable connection? I've yet to look into that. My place is wired for cable, though I don't have cable TV. Cable internet runs on the same cable, eh? Do you have to have cable TV to get cable internet connected?

        Drawbacks? One thing one hears is that with a high-speed connection one has to be more careful about nasty people trying to hijack your machine. True or false? I've been pleased with the free Zone Alarm firewall I installed on this new computer I bought a week back. Would I need fancier shields up if I was running on cable?

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        • Jagermeister
          Senior Member
          • Aug 2005
          • 876

          #5
          High C:

          The splitter box on the outside is "standard" DSL (ITU G.992.1 or G.992.3). There is also a lower rate version called "splitterless" that uses in-house filters at the wall jack, ITU G.992.2, commonly known as G.LITE.

          The point is, some people may have the box on the outside of the house, and some people may have filters they place inside at their phone jacks. The instructions that the carrier provides will dictate the proper course.

          Comment

          • Gonzalo
            Senior Member
            • Sep 2004
            • 1785

            #6
            For normal voice service the phone line from your house connects to a "line card" at the phone office or at a remote station between your house and the office. That line carries audio frequency analog signals from your phone to the line card, where they are digitized and sent over the phone network. This type of service is called POTS, for "Plain Old Telephone Service."

            For DSL, the DSL modem at your end puts the data from your computer into a modulated high frequency signal that goes over the same line. At the phone office (or remote) your phone line is routed first through a "DSLAM" which stands for Digital Subsciber Line Access Module, where the data from the high frequency signal is read by a DSL modem and sent to the internet through routers and other network equipment operated by the phone company. In some cases the data may be sent by the phone company to a ISP such as Earthlink. Your POTS line then goes on to your line card and functions normally for voice traffic.

            There are variations of this arrangement. Sometimes the DSL modem and DSLAM are included on a special type of line card that has both POTS and DSL functions. Sometimes the DSL modems in the phone office (or remote) are built into the DSLAM and sometimes they are in another box connected tot he DSLAM. But essentially that is how it works.
            Wherever you come near the human race, there's layers and layers of nonsense. --Thornton Wilder, Our Town

            Comment

            • Sailortect
              Gluten Enthusiast
              • Dec 2001
              • 13641

              #7
              Originally posted by Jagermeister:
              Also, your in-house wiring must be in relatively good shape. Excessive numbers of extensions can cause signal degradation and disrupt DSL.
              Aha. I knew it was too quick-and-easy to be true.

              True to family form, the office phone system was set up decades ago by some friend of my uncle. Whenever we need an extension changed or any other modification, we drag this poor slob out of retirement and pay him in booze.
              The voice lines are quite noisy as it is. For example, when you're on line 1, and someone picks up line 2 and starts dialing, you can faintly hear the dailing on line 1.

              I suddenly am far less enthused about this whole thing.
              People today will buy a car with square wheels as long as the steering wheel is heated.

              Comment

              • High C
                Senior Member
                • Mar 2003
                • 8984

                #8
                Originally posted by Jagermeister:
                High C:

                The splitter box on the outside is "standard" DSL (ITU G.992.1 or G.992.3). There is also a lower rate version called "splitterless" that uses in-house filters at the wall jack, ITU G.992.2, commonly known as G.LITE.

                The point is, some people may have the box on the outside of the house, and some people may have filters they place inside at their phone jacks. The instructions that the carrier provides will dictate the proper course.
                Ahh! Well, that's a nifty improvement, making installation much easier. Splits 'em right at the jacks, in effect.

                Obviously, I'm a cable guy.

                Ish, typically, cable and DSL cost about the same. It's not a given, however, that your cable company offers Internet service. Ax 'em. And they may or may not bundle it with TV and/or offer Internet alone. They each play their own game.

                Comment

                • meerkat
                  Senior Member #4667
                  • Feb 2002
                  • 21774

                  #9
                  Originally posted by ishmael:
                  I'm too far out, so to speak.
                  You really are too far out if you haven't noticed that we speak of it all the time!
                  If you don't think for yourself, someone else will do it for you!

                  Comment

                  • meerkat
                    Senior Member #4667
                    • Feb 2002
                    • 21774

                    #10
                    Cable = Party Line. [img]tongue.gif[/img]
                    If you don't think for yourself, someone else will do it for you!

                    Comment

                    • High C
                      Senior Member
                      • Mar 2003
                      • 8984

                      #11
                      Originally posted by Meerkat:
                      Cable = Party Line. [img]tongue.gif[/img]
                      The entire Internet is a party line.
                      [img]tongue.gif[/img]

                      Comment

                      • meerkat
                        Senior Member #4667
                        • Feb 2002
                        • 21774

                        #12
                        Not like cable or a local network is (same difference).
                        If you don't think for yourself, someone else will do it for you!

                        Comment

                        • High C
                          Senior Member
                          • Mar 2003
                          • 8984

                          #13
                          Originally posted by Meerkat:
                          Not like cable or a local network is (same difference).
                          I do know what you mean, that if your neighbors all download porn at the same time, my access slows. I suppose that could be an issue if you have a lot of neighbors sharing the "LAN", but my cable service smokes along day in/day out with never an observable loss of speed. (excepting a spell of nasty weather we had recently )

                          Comment

                          • Bruce Hooke
                            Senior Member
                            • Mar 2000
                            • 14297

                            #14
                            On cable...

                            1. At least around here, DSL is a LOT cheaper than cable, especially if you do not have cable TV. DSL is now available here for about the same price as (or even less than) dial-up, whereas last I checked cable was upwards of $40/month! The cable company does offer a deal whereby you get a discount if you get multiple services from them, however, I was able to get just cable Internet access without also getting cable TV.

                            2. In my experience, cable is faster than DSL, but not by enough to matter for most purposes. Either one should be a LOT faster than dial-up.

                            3. Cable Internet does run on the same cable as cable TV.

                            4. With any sort of high-speed Internet connection your computer is always connected to the Internet, which gives the bad guys much more opportunity to break into it. However, a decent firewall and suchlike should protect you just fine. Note: This is way Windows XP makes itself very annoying if you turn off the Windows firewall and it can't detect another active firewall.

                            You'll have to check with your cable company to find out if they even offer it. I know that when I signed up for a cable Internet access a few years ago the guy who came to do the installation said that it was nice for a change to be doing an Internet hook-up rather than yet another TV, which is what he spent most of his time doing. This should give you some idea of the relative popularity of cable TV versus cable Internet...

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                            • Bruce Hooke
                              Senior Member
                              • Mar 2000
                              • 14297

                              #15
                              Originally posted by High C:
                              </font><blockquote>quote:</font><hr />Originally posted by Meerkat:
                              Not like cable or a local network is (same difference).
                              I do know what you mean, that if your neighbors all download porn at the same time, my access slows. I suppose that could be an issue if you have a lot of neighbors sharing the "LAN", but my cable service smokes along day in/day out with never an observable loss of speed. (excepting a spell of nasty weather we had recently )</font>[/QUOTE]That was my experience too. I suspect this issue would mostly show up if you were in a situation where you really did share your cable line with a lot of other people who use it a lot for Internet Access. I suspect this would mostly come up in situations like apertment buildings occupied by a lot of heavy Internet users, or a complex with lots of small businesses that all use the same cable hook-up. I suppose it could also be an issue if you, say, live in a well-off neighorhood with a lot of families who have multiple home computers and kids who surf the net a lot in the evening...

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