Using DSL Modems for Point to Point Connections? 57
Tommydog asks: "Any techies out there? I'm living in a rural area and would like to know from anyone qualified, if I can hook up 2 DSL modems point to point, and connect to a neighbor's home network who is running Internet Sharing. We do have a dry pair (we can only get one pair) of TELCO wires between our houses, which are about 2 miles apart. Before investing in a couple of single pair modems (T-1's require 2 pair), I'd like to know if anyone has been able to make something like this work. It turns out that I'm just a bit too far for DSL, but this neighbor does have it and will share it if I can get a good connection going. So, anyone have 2 DSL modems working point to point, back to back? Are there any caveats or precautions? Thanks!"
Very quickly.. (Score:3, Interesting)
You may have already considered this, but most ISPs that I'm aware of have a line in the ToS that states that you may not share the connection with other people. And they do check; I remember a friend getting his house checked by Road Runner due to his daughter using P2P out the wazoo.
speakeasy.net allows connection sharing (Score:2)
Re:Very quickly.. (Score:1)
Re:Very quickly.. (Score:2, Interesting)
Re:Very quickly.. (Score:1)
cut the cord...use high-powered wireless antennae (Score:5, Informative)
However, he wanted to sit in a coffeeshop in town and use his home network, so he claims he installed a couple of high powered "pringle antennae" [arwain.net] climbed tree, installed another one as a repeater in a tree somewhere (to get around a mountain) and he was in business. Shouldn't be too hard to line-of-sight something 2 miles.
Re:cut the cord...use high-powered wireless antenn (Score:1)
But this guy already has the wires.
Maybe it would be easier for him to use them.
Ask Google before asking Slashdot. (Score:1)
Yes (Score:4, Informative)
I suspect that if you want to do this cheaply you would be best off finding an ISP that experimented with "rolling its own" around 1998-99.
Re:Yes (Score:5, Informative)
I've seen these things work at 11,000 feet, and the manual for mine says it's possible to use for up to 18,000 feet (measured by line impedance). If you're 2 miles drive from your friend's house you could have 20k+ feet between the two of you, or worse, your line could go through the CO on the way there. If you're too far out for DSL from the CO, you're definatly too far from your friends house if your line makes a stop at the CO first!
Re:Yes (Score:1)
Re:Yes (Score:1)
Re:Yes (Score:1)
Re:Yes (Score:2)
Re:Yes (Score:2)
One caveat (Score:2, Informative)
Sharing the connection is probably against the DSL provider's terms of service. Your friend might want to look into that before sharing the connection.
Re:One caveat (Score:2)
I can't see how it would be. It's no different than sharing the connection between an upstairs computer and a downstairs computer. Most ISPs' policies have clauses prohibiting reselling their services, but they'd have a real hard time prohibiting freely sharing the bandwidth that the subscriber has paid for.
Re:One caveat (Score:2)
Most ISPs do not allow the connection sharing within a home either.
Re:One caveat (Score:4, Insightful)
Prohibiting an action that could take business away from the ISP is entirely logical, but prohibiting an action that has no effect on the ISP whatsoever is not. If I'm paying for a 768Kbps DSL line and I'm not reselling that bandwidth, the ISP should keep its nose out of my business. I'm paying for that bandwidth and what I use it for is up to me until it begins harming the ISP.
I also have a real problem with ISPs that crack down on users who do lots of filesharing. Since I pay my ISP for 24 hour 768Kbps access, I expect to be able to utilize all the bandwidth I'm paying for (minus TCP overhead, of course) all the time. An ISP telling me I can't use all 768Kbps all the time because they haven't got the capacity is like the cable company telling me I can only watch HBO fifteen days out of the month. It's their job to have the capacity, since I'm paying them for it.
Re:One caveat (Score:2)
Of course ISPs oversell their bandwidth. Do the math!
The telephone companies oversell their capacity, as do all public utilities.
Some ISPs are a little more forthcoming of their exact expectations for "fair use", and do advanced rate-shaping so that you'd get 1Mbps for three hours, but then only 250kbps after that, or something.
Mighty hard for them to stay in business if they don't. Getting big pipes is still expensive! I'm actually surprised how much bandwidth costs have NOT fallen, given how much dark fiber there is.
- Peter
Re:One caveat (Score:2)
It's no different than sharing the connection between an upstairs computer and a downstairs computer.
Many ISPs prohibit even that under the standard contract. Sure, they don't enforce it, but that doesn't mean they couldn't.
Most ISPs' policies have clauses prohibiting reselling their services, but they'd have a real hard time prohibiting freely sharing the bandwidth that the subscriber has paid for.
The cable companies have no problems doing it. Just use a term such as "single dwelling."
danger will robinson (Score:1, Interesting)
a tech for sbc (who i have no reason to believe was lying - we were speaking friendly at a resteraunt) told me that they screw with service on local lines and can cause techs to get electrocuted because the lines aren't flagged.
Re:danger will robinson - stupid (Score:4, Insightful)
Maybe not enough power to electrocute someone, but there is enough power on a phone line to cause a tingle (especially if you touch the bare copper while a ring is sent through). Thing is, dry pairs aren't the only ones that can do that... all lines can do that.
Re:danger will robinson - stupid (Score:2)
Re:danger will robinson - stupid (Score:1)
A static shock has a bajillion volts, but not much amperage.
analogy:
"Man, there was this guy, in this massive water pipe! He could have gotten killed!"
"Was there any water in this pipe?"
"Well, a trickle on the bottom, but it was a HUGE PIPE!"
Re:danger will robinson - stupid (Score:1)
Enough to cause the muscles in my arms to rapidly contract. When I was a little kid, somewhere between 8 and 10, just getting into lower level electronics, I didn't know what the voltage was on a phone line, and so I was stripping live phone line wires with my teeth (my parents wouldn't buy me strippers) to run a cable to my modem, and the phone rang. Yow!
Re:danger will robinson - stupid (Score:1, Offtopic)
If my parents had bought me strippers...
Yow!
Re:danger will robinson - stupid (Score:2)
The amperage is enough to ring your phones - there's no circuit breakers inside the customer's house, so they'll suck as much current as they need. The lack of a breaker is because it's really typically not needed for residential use - phone lines only have high voltage during the short burst of each ring. The rest of the time there's just low signal voltage and extreme low current.
US electrical code requires 14GA cable for 15A and 12GA for 20A power, but phone service typically should never even reach 1A so 24GA cable is allowed - it's considered low-voltage even though it gets brief spikes of mid-voltage.
BTW, the reason the phone company uses 90V power is that originally the US power grid was also 90V, so the phone company could use the same power generation equipment as the electrical companies. But house voltage has slowly crept up, first to 100, then 110, 115, and now finally 120. I've even seen some places in the US that use 125. THe phone company sticks with 90 anyway.
Re:danger will robinson - stupid (Score:2)
as for hooking up DSL modems to a dry pair, i've heard of it being done, just done know how. also the telco may have put a filter on the lines that'll keep dsl from working.
Re:danger will robinson - stupid (Score:1, Offtopic)
You should get real. It requires very little 'power' to disrupt the heart. The resistance of the skin is what usually keeps this from happening. If you have bare dry hands, you're probably right - but:
The C.O. will send enough voltage to make an old-style mechanical ringer operate. It's a constant-current source (ie: it will raise the voltage until the appropriate current flows). With no phone on the line, you'll get maximum voltage as the C.O. attempts to make the electrons flow.
Again, the resistance of your skin is the deciding factor. Get your hands wet, or let the wires pierce your skin at the same time the C.O. decides to ring your phone and could could easily become dead (remember to hold one wire in each hand if this is your goal).
As a reference (current in *milliamps*):
Unsafe current values:
8 mA to 15 mA
Painful shock; individual can let go at will since muscular control is not lost.
15 mA to 20 mA
Painful shock; control of adjacent muscles lost; victim can not let go.
50 mA to 100 mA
Ventricular fibrillation - a heart condition that can result in death - is possible.
100 mA to 200 mA
Ventricular fibrillation occurs.
200 mA and over
Servere burns, severe muscular contractions - so severe that chest muscles clamp the heart and stop it for the duration of the shock. (This prevents ventricular fibrillation).
http://www.elec-toolbox.com/Safety/safety.htm
A.
Re:danger will robinson - stupid (Score:1)
Re:danger will robinson (Score:1)
This will sound insane. (Score:5, Interesting)
Have you considered putting in a fiber link? On ebay, I just saw a 9k ft spool for ~$200 buyitnow awhile back. $30 for some 10baseT transcievers at each end. Renting a trencher for a weekend would cost what? Hell, it might be alot of work, but in 2 years when you decide you want a 100baseT link, or even gigabit, you buy some more (by then) cheap transcievers. For that matter, you might even be able to find the equipment to multiplex cable tv over the damn thing, if you wanted.
Just a thought.
Re:This will sound insane. (Score:1)
Posts like this are why I keep reading Slashdot. The original dude's question was rather interesting, but this suggestion is even more so. I didn't even know you could do something like this! There may be a lot of trolls or MS-bashing or whatever, but when you boil it down, Slashdot has tons of geeks who know and have tried some pretty cool things.
Thanks, Slashdot, and my fellow geeks! Keep up the good work!
Doug
Re:This will sound insane. (Score:2)
For one thing, both parties have to own all the land in between, how likely is that?
I have no idea how much shipping would be, for a spool that big... it might double the price easily (which would still be reasonable, imo). But, if I understand things correctly, this stuff has the equivalent of conduit attached, so that's not an expense. You'd also need to hire someone to polish the ends, and put some connectors on it... but maybe someone with the tools wouldn't mind earning an extra $100 on the weekend, for what would only be 20 minutes worth of work. Alot of work, and even a fairly large chunk of cash, but it would last decades. Re-usable in ways that we probably can't even imagine at this point.
I'd certainly be considering it, if I were him.
(Offtopic) (Score:1)
--That is pretty well accurate. I just added you to my friends list, bro.
--I ended up taking the "corrosion" link off my website 'cuz I didn't want them getting any more hits off me. Elitist punks... They'd rather delete my article contributions than discuss why the idea presented might be wrong!
Re:This will sound insane. (Score:1)
Re:ummmm...... (Score:3, Informative)
Also, you're wrong about 100 feet being the max length of ethernet. It does 100 meters using UTP (Unshielded Twisted Pair), which is 300 feet.
Re:ummmm...... (Score:1)
1948 units, 71 prefixes, 28 functions
You have: 100 meters
You want: feet
* 328.08399
/ 0.003048
only one pair? (Score:2, Interesting)
i dont suppose you have any sort of cable (ie co-axial) connection running down those poles do you? might be able to get a dry line there and convince an old BNC'd ethernet card to shove data down it.
also remeasure your distance. is he two miles straight down the road or two miles across a field and thru the woods?
looks around im sure ive seen some people using microwave, wi-fi, laser, and radio over those distances jsut in case your DSL doesnt go.
yea im sure this post helped you a lot.
link to older Slashdot discussion (Score:5, Informative)
BTW, if your phone company won't take your order for a "dry pair," ask for an "alarm circuit."
You should be able to just plug both of them in, configure your TCP/IP stacks to use the DSL "modem" as a gateway, and you're off to the races.
Etherloop (Score:4, Informative)
We are currently using them to phase out some ISDN lines. At $175 a pop (need 1 on each end) it's pretty economical. Currently "modem to modem", but we have some actual DSLAMS were going to be installing shortly.
They will work on just a dry pair, or a pair with tone on it. The builtin POTS splitters work fine, even modem to modem. The only issues are getting access to the cabel plant... not that big a deal for "us" as we are on a military base and own the plant, but probaly dificult for normal telco lines.
Their documentaion is kind of poor, but the products are great. You have to call them and track down a re-seller which is a pain, but worth it.
possible for some DSL flavors, but not others (Score:5, Informative)
there are many types of DSL... ADSL, SDSL, HDSL, VDSL, SHDSL, etc. they are divided into 2 main groups: Symmetric and Asymmetric.
the "symmetry" of a DSL modem refers to the way the frequency spectrum is divided up. above the voice spectrum, there is an upstream data spectrum followed by a downstream data spectrum. in Asymmetric DSL types, the upstream spectrum is much smaller than the downstream spectrum. in Symmetric, they are the same size.
since ADSL modems have different size spectrums for upstream and downstream, they do not connect to each other.
Symmetric modems, on the other hand, are more readily connectible to each other. but, most need to be configured so that one will act as the "central office" device, and the other will act as the "consumer premise" device.
the other thing that needs to happen in order to connect symmetric devices is configuring the ATM settings properly. DSL devices use Asynchronous Transfer Mode to transfer data across the line (this has nothing to do with your local network). most devices use a PVC of 8/35; it doesnt matter which one you use, as long as they're both the same.
so, your best bet would be to use two Symmetric modems with consoles that you have access to.
Depends on your equipment (Score:3, Interesting)
If you want to spend a few bucks ($1000 per end), Adtran makes some good HDSL gear - such as the Express-L768, and Express-L1.5, that will do what you want. The L-768 is probably what you want, as it uses a single pair, and runs 768K bidirectional. (The 1.5 runs at 1.5M, but uses 2 pairs.. it can also run 768K on a single pair.)
We use these at a number of sites, and they work pretty well.
There are caveats.. the maximum distance you can drive them is 18000 feet.. and if you're leasing copper from the telco, you have to watch the distance.. the telco here bills length as crow-flies distance, so unless you know their distribution network, you may not know the exact footage.. for example, we have two schools that are about 3 feet away from each other (next door), but the actual cable distance was over 20000 Feet. (The copper for each site runs back to the telco's distribution point.)
If you own the land between the sites, I'd do as another poster suggested, and run fiber)
We have 4 of these... (Score:2, Informative)
Until about a year ago, Sprint would allow us to order these point-to-point dry pairs. Since we didn't have any other type of broadband (except Sprint's "reasonably priced" frame-relay circuits ~$700 for a fracT1) we used these circuits with PairGain 300S sDSL modems. These are manually adjustable from 128kbps up to 2048kbps depending on the distance and quality of the lines. They work very well. We were able to use them with circuits approximately 2-3 miles long at speeds of 384kbps and in one case the line quality was good enough to support 768kbps.
There is a huge difference between a modem and 384kbps circuit. I highly recommend them.
That being said, these modems are very expensive. I haven't priced them in several years but they were about $900 for a pair a couple years ago.
Check Out Zyxel DSL Modems (Score:3, Informative)
Check out the SDSL / GSDSL Devices from Zyxel; I'm using a lot of these in back-to back configurations covering distances in the range from ~ 300ft to 4 miles.
I'm using two differnt models: the older Prestige 681 [zyxel.com] SDSL Modems/Routers and newer Prestige 782R [zyxel.com] G.SHDSL Routers.
Both have a max. linespeed of ~2Mbits; what you actually can get depends both on line quality and distance. Under identical conditions, the newer 782R will get about 20-30% higher troughput.
From my experience I'd expect to get about 1 - 1.5 Mbits over a 2 mile link if it's reasonable quality.
There's probably lots of other devices that would also work, it's just that I've successfully used these myself. Prices (new) in Europe are about $480 each; with a bit of luck you should be able to get them used for a lot less.
Why hasn't anyone posted this url yet? (Score:4, Informative)
This guy lives in rural washington, and had the same problem. This is his complete step-by-step how to on how he did it, including modem brands & models, problems he had while setting it up, how he overcame obstacles, etc. Very very good read and I would think it'd be your first stop for rolling your own.
daisy chaining? (Score:1)