View Full Version : What happens when you have DSL and dial-up on the same computer?
05-18-2003, 03:59 PM
OK, my computer is currently hooked up to my DSL router through my NIC. The DSL is hooked up to the modem, the modem to the phone jack. If I were to hook another phone jack up to my computer's modem, and have both connections running simultaneously, what would happen? Would the computer recognize both connections and just use the additional 7KBPS of bandwidth to help the DSL assuming I'm downloading something at my max? Would I now have bandwidth of 768kbps + 56kbps download and 128kbps + 33.6kbps? Would it subtract from the total? I've been wondering about this sicne I got DSL. Thanks for any future replies, by the way.
05-18-2003, 04:04 PM
I have DSL and 56K modem on the same computer but I have never tried to see if the 56K modem would "help" the DSL. I do know I can connect using either one with no problem though.
05-18-2003, 04:08 PM
Oh, make that "128kbps + 33.6kbps uploaded" and "since."
05-18-2003, 04:11 PM
If you are running Windows, it would confuse it badly. What you will have is two routes to the internet and the PC will not know which one to use to complete a given task. It will not add both together to increase speed, but might even slow you down as it tried to decide what connection to use. Windows just was not designed for this. You can set static routes, but even that will not work very well because it is a manual process and is error prone and time consuming. Routers are very good at this and there are special protocols, like the border gateway protocol, that are designed to help routers and other types of network devices determine the best route to use. But Windows cannot do this very well. I would not bother with the dial up, except as a backup in case your DSL fails.
05-18-2003, 04:22 PM
Actually, most if not all Windows gives priority to the dial-up connection. What should happen (and from what I've seen it works fairly well) is that the LAN-type connection (be it DSL or cable or whatever) is correctly ignored, and all traffic routes to the dial-up.
There's a particular application I used to work with at work that used this, and I had no trouble on any Windows system I tried (and I likely tried most if not all flavors of Windows).
norinew, where did you hear it would "confuse" Windows? Did you try it and have trouble?
05-18-2003, 04:43 PM
I had dial-up, then got cable on same computer. No problems at all with XP Home.
05-18-2003, 04:55 PM
I agree with norinew; no PC was designed for this kind of combination, as tempting as it might be to try.
It's theoretically possible, tho. Not long ago, my local ISP allowed their power customers, using a special program, to gang two modems and two phone lines to one computer, doubling the thruput. But this wouldn't have worked without the special program. Satellite and cable have made this concept mostly obsolete.
And Hermann, although you have the option of a dialup or cable, I doubt if they are working simultaneously, adding their thruput. Tell us if you have verified it otherwise -- maybe XP is more sophisticated than early OPsyses.
05-18-2003, 05:19 PM
There used to be dual modem dial up computers, but your ISP would have to support them to get 2x speed & you needee TWO phone lines.
If you have DSL & dialup, & can't use the DSL, you can still use the dialup. You're supposed to use the dialup for faxing from your computer....&/or backup.
05-18-2003, 06:04 PM
The dual modem configuration is called multilink, it worked but [b]handy[/] is correct, your ISP would have to support it.
[b/]Revtim[/] is correct, windows will give preference to the dial up connection. However, if the dial up is down and it uses the lan and then the dial up comes back, the system can hang as it tries to figure out which connection to use. When you have both connected, you will have two IP addresses, and some versions of windows, (16 bit) will not be able to correctly route packets if both connections can reach the same place.
That happened to me back in ’99. I used dial up for internet access and lan for access to servers. Then the network got a net connection using a frame relay T1 and if I tried to use it while connected to the internet through a dial up connection windows would hang until something timed out and then it would start to work. Setting up a static route solved this but as I stated earlier it was labor intensive and error prone. I have not seen this behavior in 32 bit versions of windows and maybe it does not happen if you have the 16 bit versions configured differently then I had mine, but I thought the behavior was something that could have been better designed.
05-18-2003, 07:42 PM
There should not be any problem with doing this as far as the two configurations co-existing. They would exist seperately as two entries under Network and Dialup Connections in Control Panel. You can specify which takes precedence over the other.
But no, you can't combine their bandwidth into one online session.
Running a DSL and dialup on one phone line might not work very well. Those DSL filters don't always work too good.
05-18-2003, 09:46 PM
I normally have my computer on the DSL line, but for cases when it goes down or just for the heck of it, I'll switch to dialup. in ie I go to tools>internet option>connection and either select never dial my default connedtion for dsl or allways dial my default connection for dialup. If I select dialup the computer uses dialup even if a lan connection is present.
Also upload speeds on a 56k modem is something like 28.8 or maybe 33.6 w/ compression IIRC the speeds up to 56k (or 53k) is download only and is digital, while upload is analog.
05-18-2003, 10:28 PM
I have a v.92 modem so I think they fixed the upload. It says that it now has a true upload of 33.6.
05-18-2003, 10:32 PM
Nope, I've only tried either/or. I think that I took the question wrong the wrong way.
05-19-2003, 12:58 AM
I am not sure what the question is. First, you hooking a regular phone line to a cable/DSL modem won't work, besides, the modem wouldn't have two (actually three) connections anyway. Now, if you have two modems, the DSL one connects to a network card and the dialup line to a regular modem, that would work.
Now, if your question is whether you can use both connections at the same time to access the Internet, the answer is no.
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