What To Do With Old DSL Modems?

RebornData asks: "Thanks to a move and continuing instability in the DSL market, I'm now the proud owner of three DSL modems of various types gathering dust in my closet. It's a sordid tale. While I know that obselete hardware is worth next to nothing, this hardware isn't necessarily obselete, with my most recent acquisition only getting two months of use (thanks to Northpoint's untimely demise). Is there a market for used consumer DSL modems? Some of these devices (like the Telocity Gateway) are more than dumb communications electronics- are there any cool hacks out there for them?" RebornData is surely not alone in this; I am now the (proud?) owner of an Efficient Networks, Inc SpeedStream modem, orphaned along with my old DSL provider. (Read on for more.)

"Details:

My tale of DSL woe: I was an early DSL customer in Houston, and had an ADSL line from PDQ.net for a year and a half using an Alcatel DSL modem (#1) before moving to Atlanta. In Atlanta, I signed up for PhoenixDSL which used Northpoint to provision an SDSL line for me using a 3com modem (#2). Then Phoenix's business was bought by Megapath, who then sold the consumer accounts like mine to Telocity.

I was migrated by Telocity two months ago, and they sent their own "Telocity Gateway" (#3). Of course, when Northpoint kicked the bucket, my Telocity connection went down. After four weeks of stringing me along (including promises to have me back up in three weeks), they've just informed me that they can't provide me service through an alternate provider, so I'm on my own and have yet another useless (?) DSL modem. Turns out that BellSouth is the only other DSL circuit provider in my CO and their DSLAM is full so they won't be able to service me until October at the earliest. AT&T's here installing a cable modem right now. So what can I do with all this DSL stuff? From what I've experiened, most DSL providers provide their own equipment, but is there a market for used modems? The Telocity gateway looks hackworthy... I remember reading somewhere that it runs Linux internally, and there are some interesting ports and markings on it (like "for use with X10 modules"). Has anyone torn into one of these things?"

Comments

Build your own DSL links.

[Anonymous Coward]

You don't need a dslam, just rwo dsl modems. It's easy to do with netopia routers, they have a setting much like a crossover on a hub. Just order a dry pair - straight copper from point to point and plug in at both ends. With SDSL you can get some decent throughput. You can do a similar thing with T-1s, just get 2 dry pairs and wire correctly. This is a way to get a cheap ($15/month/pair connection.) Depends where you live for pricing, but still not bad. Much less than $300+ for a T1. Distances will limit you, but it's a great way to build a gorilla net. I know specifically about the netopia since I'm working for a former partner of northpoint and we had the router guy come by for a little show and tell. The netopias also do a bit of multiplexing, and you can put 2 cards in each one. so with 2 dry pairs you can get 2 lines running at 1.5mb each - 3.0Mb for $30 a month. Beat that!

Re:Build your own DSL links.

[Anonymous Coward]

I don't think you get the point. Gorilla nets are people to people, instead of isp to person. Great way to connect your house to someone elses house. I wouldn't use it for an isp because dslams are MUCH easier to manage. But if you want a use for equipment you have, there's good potential there. Make sure you really understand the limitations of dsl if you want to do this. It's perfect for connecting to your friends house for that network quake game. It's also perfect for something like GNET. http://205.159.169.11

Re:Build your own DSL links.

[tzanger]

You're right about bandwidth charges but I think you're way off with blaming "shitty dry pair DSL" with quality. I spec Pairgain Megabit Modem 300S (2.048Mbps full duplex) -- they aren't rate-adaptive but rather use a little selector-switch to set the WAN speed. I have yet to have a single problem with them and we've got over 25 pair in service. Link speeds are better than spec (our area has larger gague wire trunks than standard) and it just never goes down. Far better than Wireless if you ask me. We had a competitor to the north set up most of his links in the winter and when spring came everyone's link took a big shit. Not to mention humidity effects.

BTW: ALL DSL works over dry copper aside for the g.Lite implementations which are piggybacked on top of a regular phone line.

Re:Build your own DSL links.

[Loualbano2]

Let me clarify all that is involved with this scheme.

Yes two sdsl modems will work back to back. I am pretty sure that adsl modems will work in the same way. There is somewhat of a standard for cell based sdsl modems so there is a chance that two different brands of sdsl modems will work together. The only problem is that you have to make sure that the VCI is the same on both, which pretty much means you will have to configure them yourselves... Don't expect them to work out of the box or with the config that your provider put on them.

In order for this to work you and the other party have to be out of the same CO. You can order PADA circuits to both partys and have them cross connect them at the MDF. As far as I know there is no way to do this between COs as telcos stopped running straight pairs between COs a long time ago, and NO you cannot just get switched through the voice network. The POTS network or even the ISDN network cannot handle the frequencies that DSL works on which is why DSLAMs and DSL was ever invented.

You also gotta make sure that the telco doesn't put load coils or ringers on the circuit. I have seen this happen even though our order specifically said not to put these things on there. How do you check? Use a TDR box. Also you have to make sure you never tell them you are using them for data. These circuits are suppoesed to be for alarms and there may be laws that are being broken here.

Your max throughput would be 2.3Mbit, depending how you set up the modem, the model and the distances involved. Oh, and don't try to use any type of map to guage the distance, the telcos rarely take the shortest path to the CO. How do you know length you ask? Bust that TDR machine again.

The circuit is not full duplex and not even really aggregate, which is weird. I would guess with two transfers in each direction you would see about 1.3-1.5Mbit both ways.

Oh, and if you are served off of a DLC you can just forget this whole idea, unless you want to drop a hardened DSLAM into your DLC.

Does all this sound like a lot of trouble? Imagine all these problems and variables times 10000 and you can imagine why (insert this week's defunct DSL provider name here) went out of business.

Re:Build your own DSL links.

[tburkhol]

This is true, but then you have to pay for bandwidth, the $15 is just the line charge. I don't know of any ISP that will give bandwidth away, especially a t1's worth of it.

No ISP is involved in the scheme AC suggests, so there would be no bandwidth costs. The theory is that you pay the phone co. for a dedicated line between, say your house and your next-door-neighbor. They don't care what you do with it. Presumably, you and your neighbor can then make your 2 DSL 'modems' talk to each other since they're the only things on the wire. (btw, it's not necessarily a physical wire running directly from you to your neighbor, but routed through the phone co. system

I don't know that DSL modems work that way...it's not like hooking up your 56k. I'm just trying to clarify the proposal.

Fun with DHCP!

[Anonymous Coward]

If one of your DLS boxes has a DHCP server, find someone you don't like and attatch it to their network. Then hide it.

Sell them to the UK

[Tony Hoyle]

They're like gold dust over here. The encumbent
telco (BT) try to force everyone to use crappy
USB modems which hardly work (they draw something
like 500ma off the USB bus, which means they have
to be the *only* device on the bus... if they work
at all).

As long as it's smart enough to do PPPoA (no PPPoE over here) there's someone will pay for it.

Someone mentioned this..

[RAruler]

Theres a Do-It-Yourself DSL website for DSL. Here.

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Re:Telocity dsl router....

[Gill Bates]

I've had Telocity for a little over a year now. When I first got it, I attempted to figure out what it was running for an OS (BTW, all of the above can be determined without cracking open the case). Telnet to the modem on port 80 yields the following:

Trying 10.5.1.2...
Connected to 10.5.1.2.
Escape character is '^]'.
HTTP/1.0 504 N/A
Connection: close
Server: Expressway WindWeb/1.1
Date: SUN APR 29 09:13:53 2001
Content-Type: text/html

Telocity Expressway Web Server Error Report: V1.1<HR>
<H1>Server Error: 504 N/A</H1>
Operating System Error Nr:3997700: errno = 0x3d0004 <P><HR><H2>URL parsing error
</H2><P><HR>please mail problems to support@telocity.net <A HREF="mailto:support
@telocity.net"><ADDRESS> Telocity Communications Inc. 10355 N. De Anza Blvd. San
Jose, CA, 95014-2027</ADDRESS></A>
Connection closed by foreign host.

A google search leads to Wind River Systems (http://www.wrs.com) and implies that the modem is running VxWorks, not Linux (as the article submitter implied).

Telocity dsl router....

[dr4ma]

I would think that the telocity brouter(it does both bridging & routing) seams to be largest of interest to me at least. I cracked mine open the first day I got it wanting to know what was inside! its a 50mhz PowerPC processor(no heat sync), 4MB FLASH ROM, and 16MB of ram. now remember, this thing also has a USB port and 2 rj45's(WAN/Local). I'd imagine(thinking creativingly) that you could make your own router/bridge running netBSD or possibly linux. right now netBSD has more platform support out there, and bsd would handle that little amount of ram much better then linux would. but yeah, see what you can do, there are also a couple of jumpers in there, probably for upgrading the firmware on it.
any people with info on this interesting piece of hardware with alcatel power please, do post it!

ebay, ebay, ebay

[eltardo]

I actually work for the DSL side of Verizon and I've run across a lot of our former customers selling the modems on Ebay. Believe it or not there seems to be a market for them there.
Word to the big bird.

Standards in RADSL

[CBOS]

There are three basic types of RADSL Line encapsulations.

CAP (Carrier Aplitude Phased)
DMT (Digital Multitone)
G.Lite

For RADSL service to work the DSLAM that you are connecting to and the modem that you have need to be using the same line encoding. If you check with your local provider and find out what line encoding they are using, you should be able to use any modem that uses the same line encoding. CAP is going away but DMT and G.Lite are going to be here for a while.

On old modems...

[dfenstrate]

Keep the one you like the best, because there's no reason you shouldn't be able to use it if you get another DSL connection- I work at the U of New Hampshire interoperability Lab for ADSL, and we've tested equipment for all three of those vendors you've listed, and 60 other companies too, against 15 different DSLAMS. They all adhere to the same standards- g.dmt and the older ansi t1.413 (you only have to keep an eye out if you sign up for g.lite, splitterless adsl), they're supposed to interoperate.
While I can't say much because of confidentiality matters, I can say that those three companies- Alcatel, 3com, and Telocity- shouldn't give you any trouble on other systems. Only three settings really matter- VC, VP, and protocol, and if you can figure out how to set those, you're golden. There are companies that don't interoperate worth shit (one company sent us 5 different modems, one for each DSLAM they wanted to test against. I guess they missed the 'interop' part in our lab name), but in general, if a company tells you that you need to buy their modem, they're either lying or using crap for equipment.
Incidentally, while there are about 80 vendors for modems, there are only about 5 different chipset makers. You do the math

G.lite doesn't extend the distance at all...

[dfenstrate]

The benefit of G.lite is two fold:
1. You don't have to install a bandwidth splitter, so the company doesn't need to send a truck out- they can just send you the modem. This saves big bucks for the phone company.
2. They have fast retrain, which means that when you pick up your phone to make a call, the DSL service is re-established in less than 2 seconds. Picking up (and then hanging up) your phone drastically changes the characteristics of the line for a moment, and DSL connections can't stay established through a transition like that.
Other than that, there's no advantage to G.lite- it suffers from the same distance limitations. You could say you get full rate G.lite for a greater distance than normal ADSL (G.dmt), but that would be misleading, because full speed for G.dmt is around 8 Mbs (theoretically 14 Mbs), while G.lite is 1.5 Mbs. With respect to distance, when the max rate for G.dmt drops to the max rate for G.lite, they both start to lose bandwidth at about the same rate.
Another slight difference is that G.lite can only be used in the interleaved channel, while G.dmt can be fast or interleaved. Interleaved uses a more involved trellis coding and error correction than fast channel, and therefor gets higher data rates at greater line lengths. At lower line lengths, it gets lower speeds than the fast channel. Also, Fast channel has lower latency (but they're both so low, you shouldn't notice the difference)
If you want to check out the site for the lab I work at, go here: http://www.iol.unh.edu/consortiums/

Re:Check your facts first......

[Rager-vs-Machine]

Don't know about you, but a device that modulates multiple analog frequencies for upstream and downstream communications is called a MODEM [modulator/demodulator] in my neck of the woods! ADLS does this as does Cable. It's a modem that has a different frequency range, and tries not to step on either your existing voice range or cable TV range.

Hint -- That's why you only need one line for DSL and phone. Between you and the CO you can utilize far more frequencies on the UTP wire than the PSTN will allow thru the switches. Once your signal gets to the CO, the DSLAM creates a real digital stream [de-modulates the analog signals]

See these links for a good overview of ADSL technologies that Communications Systems Design published a couple issues ago:

Part I - ADSL Physical Layer
Part II - ADSL Handshake/Upper Layers


Your nitpick is correct with ISDN, but incorrect with ADSL. ISDN is a truly digital signal, and the CPE devices are called Terminal Adapters. Perhaps HDSL and IDSL are different, but ADSL and Cable technologies are not true digital signals to/from CPE......so the devices are called modems. ISDN is pretty much dead, but I seldom hear folks call the CPE device for ISDN a modem.

Don't get rid of them just yet!

[MwtrV]

Speedstream efficient networks DSL modem, the one I got, is USB based. That means no Linux, FreeBSD, any sort of UNIX support. One i bought off Ebay was an older Infospeed modem that interfaces to an ethernet card. I *HAD* to buy it because Pacific Bell (god, what a horrid experience I did have with them on DSL...it just wouldn't work for anything) wouldn't supply me with one that interfaced with ethernet.

True, they don't go much for ebay anymore. What I paid $70 for goes for about $30-$45 now. Everyone sees the new models with the higher speed ratings, and some people question compatibility. I'd be willing to bet the older ones work fine. Besides, how much speed do you really expect to get with the basic level of service?

Anyway, the point I'm making is with so many DSL providers providing Windows centric modems (thus, I choose cable, seeing the rotten state Pacific Bell was in) they are of atleast SOME value to users of UNIX workstations/servers.

Some of them are just routers

[sporkinator]

And there are hacks out there to enable them as full routers, depending on the make/model of your DSL modem. Have you checked out DSL Reports?