Talk:Digital subscriber line

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MBps vs Mbps[edit]

I noticed that the article uses MB and KB instead of the more common (in networking) Mb and Kb (Byte vs bit) please verify the numbers are correct and change or include the Mbps/Kbps values! I suggest using the layout xx Mbps (yy MB/second) or some variation thereof. —Preceding unsigned comment added by (talk) 16:35, 18 May 2010 (UTC)

2 related comments. The correct abbreviation for kilo is "k", not "K". The second paragraph mentions 384 KB; should this be 384 kb (kilobits, not kilobytes)? —Preceding unsigned comment added by Nikyzf (talkcontribs) 12:19, 31 August 2010 (UTC)

The convention is to spell out the "bit" to make it clear. For example, kbit/s or Mbit/s. W Nowicki (talk) 18:02, 14 September 2011 (UTC)

No title[edit]

Can anyone add coverage over ADSL2, or ADSL2+?

I capitalized Ethernet. Ethernet is always capitalized. --imars 09:31, 22 Nov 2004 (UTC)

This page could use an explanation of the difference between fast channel and interleaved DSL. I don't know enough to write it myself. mvc 19:48, 8 August 2006 (UTC)

I cut this:

Some of the common "DSL Killers" are:

  • Bridged taps
  • Load coils
  • "SLIC" boxes, or splitters, where copper capacity is increased by extending with multiple fibres. DSL can't travel over fibre, and most telephone companies choose not to offer fibre connections to residential customers.
  • "DACS" boxes, where two baseband analog telephone lines are multiplexed over a single copper pair using ISDN-like technology to connect to the central office. Neither of the multiplexed lines is then usable for either DSL or ISDN service, as there is no metallic high-frequency path available. Where the central office connection is demultiplexed to analog connections, there is the added disadvantage that standard analog modem speeds are also reduced significantly.

As I'm not sure what its trying to say. You obviously need a continous copper line from CP to CO and I think this muddies the waters. Alex

I see that the titles Asymmetric Digital Subscriber Line, Integrated Services Digital Network, Asynchronous Transfer Mode, Asymmetric Digital Subscriber Line, and Digital Subscriber Line are all capitalized. These articles tend to have lots of incorrectly capitalized letters in the body of the article, and that makes me suspect that someone may have written them as capitals under the incorrect impression that the Wikipedia convention is to capitalize words in article titles? What is going on? Michael Hardy 21:23, 2 Aug 2004 (UTC)

dsl inventor[edit]

I am aware DSL technology started in Bell lab at around 1988. However, i can't see to find the guy behind the technology. A used google to try and look it up, but it looks like hundreds of people are claimimg dsl as their invention. This make it all the more important to find the real inventor and give credit to the right guy. I am aware that all inventions are progressive work and that Claude Shannon did most of the theoritical work, but then humans like personalizing achievement and hence the need of the guy who put things together and called it dsl. GITLIN, Richard claim to be one of them in this article [1] Anyone know the history behind this? (Hint)His 1st name is Aaron...and lives in San Diego county..

As a Practical Matter: How Fast Does It Go?[edit]

We're all looking for value and for that reason I've always gone for the cheapest DSL I could find knowing that TPC (The Phone what 60's movie was that used as a synonym for Big Brother) will always let you upgrade/increase speed/spend more money whenever you want as opposed to the opposite.

Plus, my line has always been fast enough for me, so why pay more?

Rather than give another speed test here, I'll give you a verbal/conceptual description of what throughput looks like on my setup, along with a detailed description of my setup. Until recently (1990ish to 2007) I have use my DSL only for heavy surfing. I've done major downloads (including full Linux setups) but generally only while I was away from the screen. That is I don't do major downloads while I'm trying to surf. I have a bottom rung fast machine (32 bit, 2GigHz, 1Gig memory, 200(?) 400(?) MHz Front side buss. ~4000 RPM ATA disks.) (Mid range would be faster hardware & wider buss (64bit), High range would be fastest hardware, widest buss, multiple processors.)

In all this remember: At max, the DSL is only 2/3 as fast as a 10Mb ethernet. There should be no delays. But an ethernet is like people hollering into a long tube. As long as they are having a Push to Talk style conversation, there will be no packet collisions and things will proceed at full speed. But once just 2 people begin to have a full duplex conversation, collisions (people hollering into the tube at the same time) cause things to slow down. Naturally, multiple conversations will only make things worse.

Speed has been satisfactory with this computer and 3-6 other computers on a 10Mb Ethernet system. Only one machine is generally surfing/downloading at once. The others are used as (remote control)terminals (bedside/other desks) and storage (I have about 500Gigs of disk space on line at home. I'm a pack rat. I still have all my CP/M (pre DOS) software on line. And until recently a PC XT running DOS 5.x all on the same Ethernet.) All this was first accomplished with 10/100 Ethernet cards using co-ax. Later (Year 2000ish) I bought some $10 hubs and plugged in some RJ (twisted pair) cards. In 2007 when I moved from a 3 bedroom condo to one room, I dumped the co-ax backbone and went to all twisted pair cards on one 10/100 hub. Ultimately my pre tweak net looked like this: Phone Line -> DSL Modem -> 3Com Router -> 3 Hubs (Kitchen, Office, Bedroom). The hub in the kitchen was where the phone line comes into my Condo and distributes to the rest of the house. The kitchen hub connects to a PC inserted into the phone line as a voice info system (voice mail, database querry) and begins the coax backbone to the rest of the condo. The coax runs to the office and bedroom hubs. There are 4-6 PCx wired to the office hub via RJ twisted pair. (fast workstation, medium speed file server, slow doc scanner and any other PCs for upgrade/repair.) The bedroom hub was twisted paired to a slow notebook for remote control of all the others. All the machines had remote control installed so I only needed 2-3 keyboards/screens to control them all.

Recently I moved in with some people who are still in the stone age. I've begun providing internet service for the household. Currently there are 3 of us. One does light surfing and music downloads. I and the 3rd gent have both recently begun online securities trading. The actual trading (entering orders) is not bandwidth intensive, but it does need to be EXTREMELY ROBUST AND RELIABLE. It is not unusual for a very modest Futures Contract position to move $100 per second so you really have to be sure that when you enter an order, it gets xmitted to the exchange floor and executed ASAP. You want to get in or out of the market NOW!!

The thing that takes bandwidth is the streaming quotes. During the day, the two of us will each, on separate machines, be watching a screen that shows the number of orders and the size of the orders (number of shares/contracts) at the market price and at the next 5 price increments above and below the market. In other words there are two machines looking at 33 numbers on the screen and those numbers are changing constantly. At the busiest times, these numbers might all change constantly every 1/4 of a second. That's just a description. Don't try to calculate anything from that.

When I first reconfigured the system for the other 2 users, on my system, the streaming quotes would stop for periods of time. The numbers would stop changing for periods from seconds to minutes to large fractions of an hour. If you can't get the futures prices, you can't trade, but fortunately I was using a simulated system and still trying to work out the kinks in my computer system and my trading abilities.

The second man's system would occasionally pause and give him some kind of message about net congestion. (Naturally, the guy never told me about this until I finished upgrading the system. He was probably afraid it was his fault and I would charge him for repairs. He's kind of a newbie. Sometimes he complains that his computer is not working properly and I have to go to his room and turn his keyboard right side up.) Fortunately he was trading options so he really only needs quotes hourly.

Anyway, just from long experience, I decided that my problems might very likely be due to network congestion and I needed to try and find out where the congestion might occur and what I might do about it. If the congestion was occuring within my system, I could fix that easily. It the congestion was external to my system, somewhere out on the net....well, I'd face that when I had to. Probably with tears.

My first idea was a line speed test. They are all over. Just Google. The problem is, line speed tests are meant to be run on an idle system. I did a few tests just to establish a bit of a baseline. Results were 600-630 Download, 130-138 upload.

Tiddling around with speed test got me to looking at any numbers or settings that might affect the operation of my LAN. There was one question which has always stood out in my mind which I've to this day never been able to answer. The question is: If, on a 1/100 LAN, one card alone is capable of only running at 10, do all the other 100 cards have to drop down and operate at the lower speed? I've never answered this question, but I have implemented a solution in case this is a problem. That later.

First of my solutions was to use my router status screens and the Windows Properties (My Computer/System Props/Hardware/NICs and Network Connections/Local Area Connections Props) screens to find out what speed my NIC cards are running at and make sure they are at the highest speed and Full Duplex wherever possible. Full Duplex vs Half Duplex is the difference between a regular telephone conversation and a 'Push to Talk' conversation.

My next solution, and the solution to the 'One card on my LAN is a 10speed and the rest are 100' problem was first, to analize the traffic flow for collisions and second, see that, as much as possible, all packets flowed into same speed or higher speed equipment.

Basically, while there are multiple computers on my net, there are really 3 users. The third user is basically a surfing nerd who does most of his work late in the evening. His other use is impossible to predict. The second user just streams quotes all day. Imagine someone watching video all day. I, user one, do heavy research surfing all day as I write and sometimes stream quotes. Nights and weekends I might watch a feature movie on line. Yes. The slowest, cheapest DSL and I can watch NetFlix movies.

My interim LAN looked like this: Phone Line -> DSL Modem -> 3Com Router -connection 1> My Hub and My machines.......... -connection 2> Wireless Router to 2 roommates machines.

I had already bought another router/wireless access point to allow service to my other roommates without stringing wires as I had at my Condo. However, I had some concerns about the visibility of my computers to my roommates. As they were on the same node with one computer each, they had to turn off file sharing so they could not see each other. Initially they could not see me as I was upstream, on the phone line side, of their router but I had to turn on file sharing so all my machines could see each other. The router act as a firewall as I am on the internet side, so I could not see my roommates machines, but if they learned the tricks of local TCP/IP addressing, they would be able to see my machines also. The router does not hide the internet side from the view of machines inside the node if you know how to use local ( addressing. It is dificult and certainly beyond their talents, but that's not what you rely on to keep your net secure. Who know if they might have a geek friend over?

Plus the configuration above is still a modified One Node net. That means that everyone is still more or less hollering into one pipe as far as collisions are concerned. Worse yet, the way it was set up, their traffic would collide with my traffic, but by traffic would not collide with theirs, at least not on their segment of the node. Hubs pass all traffic in a node but routers only pass traffic destined for or passing through a node. My segment would share their traffic but their segment would not share my traffic.

My final configuration was: Phone Line -> DSL Modem -> 3Com Router -connection 1> wireless router #1 and My machines.......... -connection 2> Wireless Router #2 to 2 roommates machines. In addition, my fast workstation is RJ twisted paired to Router #1. My other 2-4 machines are connected to router #1 through a hub connected to #1. First, connecting my workstation to the router #1 should isolate it. #1 should only tx and rx packets destined for my workstation. All the rest of the traffic should be routed to the hub where my other machines reside, which are slower to begin with and have no critical traffic. Second, as I still don't use wireless on my side of the node, I needed more than the 4 wired ports available on router #1, hence the need for the hub.

It worked!! There was a noticeable increase in the speed of high traffic tasks and the problem with my streaming quotes freezing has totally disappeared. Before, if my roommate was streaming quotes, I was aware of a visible delay in loading web pages. That has gone away also. And in addition to speed, I am now sure that the machines on the node served by Router #1 cannot see any of my files on my node served by Router #2. All that is left is to try a speed test during the day when my roommate is streaming quotes.

Finished half a dozen speed tests just now with the roommate's machine streaming quotes: avg download 585-609kbps, avg upload 295-316kbps. As you will recall, when I started, the results were 600-630 Download, 330-338 upload but those results reflect a totally quiet line.

These results, plus the obvious speed increases of web page display seem to indicate to me that my LAN was being clogged by packet collisions before and now, even at maximum use, I still have about 75-80% of my bandwidth available. How much real use I get out of what's left depends on my ability to avoid packet collisions.

Tgdf (talk) 16:47, 17 January 2008 (UTC) When I lived in Seoul Korea back in 2006, we had 1Gbit synchronous residential DSL, and I imagine it is probably faster now. In Seoul Korean speed tests ask if your DSL connection is 50MBs or slower to determine which kind of tests to run. After I got back to the states I often wondered why we even have Gigabit LAN cards in computers here with our internet being so slow.Bigblair (talk) 22:57, 18 January 2011 (UTC)


There should be more on the DSL History. Like how it was at one point intended to carry Video-On-Demand. linky

DSL history - sources?[edit]

The first paragraph on the DSL page makes some claims that I haven't heard elsewhere. Some sources are needed for it(news reports, historical studies, etc.). It's good writing, and interesting, but it needs to be sourced.

The paragraph: "Its origin dates back to 1988, when an engineer at Bell research lab deviced a way to carry digital signal over the unused frequency spectrum. This allows ordinary phone line to provide digital communication without blocking access to voice services. Bells management however were not enthusiastic about it as it was not as profitable as renting out a second line for those consumers who prefered to still have acess to the phone when dialing out. This however changed in the late 90s when cable companies started marketing broadband internet access. Realising that most consumers would prefer broadband over a second dial out line, Bell companies rushed out the DSL technology that they had been sitting on for the past decade as an attempt to slow broadband internet access uptake." - diff (Also posted on User talk:Wk muriithi) JesseW 19:48, 6 Apr 2005 (UTC)

wk muriithi replied on my talk page saying he got it from "Crafting and Executing strategy 14th edition by Arthur A. Thompson Jr.". If someone who has a copy could verify this, and add it as a footnote(use Wikipedia:Footnote3 style) that would be great. Thanks for replying, Wk! JesseW 05:34, 15 Apr 2005 (UTC)

DSL "modems"[edit]

I heard some claim that DSL modems aren't really modems. Is this just BS? - Omegatron 01:18, Apr 15, 2005 (UTC)

I'd say that's BS. The definition of a modem is something that takes data and modulates it onto an analog signal on one end and then demodulates it back to digital at the other end. What's called a DSL modem can be thought of as a whole bunch of dial-up modems working in parallel at different frequencies to get you a large pipe. I've just rewritten the "How it Works" section of the main article that explains it in some technical detail. --Blrfl Apr 17, 2005

I'd say it depends what you heard...these days most CP xDSL equipment is actuall a ROUTER, typically supporting NAT, and generally also a DHCP SERVER Xaosflux 05:42, 11 November 2005 (UTC)

From 'Most residential customers call their DSL transceiver a DSL modem. The engineers at the telephone company or ISP call it an ATU-R, which stands for ADSL Transceiver Unit - Remote.' Even 'To the end-user, it is functionally very similar to an analogue modem, however the underlying technology is substantially different.' Isn't DSL, by definition, digital and not analogue? The article itself doesn't make clear what part modulation plays, so maybe that is a place for improvement. 2006-05-19 03:25 UTC

Whether you call it analog or digital is a question of which half of the hair you just split gets picked up off the table. Ultimately, what ends up on your copper is an analog signal (several of them, actually) modulated to represent digital information. --Blrfl May 21, 2006

CarlosRibeiro 00:16, 22 October 2006 (UTC). Humm. At first I though that DSL modems were modems, end of it. But then I realized that the ADSL specifies both the line modulation method (DMT) and the layer 2 encapsulation (ATM). In this sense, an ADSL end user device would be a "modem" only if it presented a ATM interface for the customer connection, which clearly is not the case for any commercial unit commercially available since 1999. (In fact, I had in my hands an ADSL modem with a 25 Mbps ATM port in 1999 - since then, all ADSL 'modems' have Ethernet ports). In other words - even the simplest ADSL devices available today (as of 2006) are a little bit more than modems because they do layer 2 protocol conversion (encapsulating Ethernet inside ATM, as per RFC1483, etc.). So we have two options - calling them "ADSL transceivers" (as mentioned elsewhere; but that's still not entirely correct) or "ADSL bridges" (which I think is the best option).

Bold text== Most widely used variety? ==

I wonder what variety of DSL is most commonly used? The only variety offered in my country is ADSL so I have no clue what is used in other countries. As I see it, ADSL is the most reliable variety, and hence the most common used. Can anyone comment on this? --Opiax 19:19, 25 Apr 2005 (UTC)

ADSL is by far the most common, but it's less an issue of reliability than one of giving the customers, most of whom receive far more than they send, high download speeds. With the exception of IDSL (which isn't really DSL; it's just a bonded pair of ISDN B channels), all of the flavors of DSL are pretty much the same from a technical standpoint. Two things differentiate them. First is the amount of spectrum above the baseband POTS signal. This is, effectively, a measure of the size of the pipe that carries all of your data in both directions. It's determined to a large extent by the basic technology in use (DSL, HDSL, VDSL) and the length and condition of the copper between you and the DSLAM. The second is whether the fractions devoted to the upstream and downstream channels are equal (for Symetric DSL or SDSL) or different (for Asymetric DSL or ADSL). As an example, my DSL line has a total of 4424 kbps available, and my ISP (Verizon) allocates 864 for upstream and leaves the remainder for upstream, giving me ADSL service. They could just as easily have allocated 2112 each way for SDSL or, if I had some special application where I needed it, 864 down and 3360 up for ADSL. --Blrfl 07:50, 16 May 2005 (UTC)

Actually, there IS a good technical reason for ADSL: at the customer end, the UPlink signal being transmitted by the modem is strong and the DOWNling signal being transmitted by the DSLAM is weak, whereas it's the other way around at the CO end. Crosstalk is much more likely to be an issue at the CO end, where local loops from a number of customers are physically close together. So the S/N is often better for DOWNLlink than for UPlink. It was good fortune that the average customer wants more speed downloading, hence ADSL made lemonade from this particular lemon.

External link[edit]

First external link is dead.

Internet Speed Calculator[edit]

There should be a calculator where you input a filesize and it outputs the time required to download/view that file on different internet speeds.

There are plenty online. -Omegatron 02:50, August 22, 2005 (UTC)

DSL Repeater[edit]

Can someone explain why there are no DSL repeaters to extend the range of DSL usage? Seems like it would be simple to have a line-powered repeater to regenerate the signal and extend the range.

See: Xaosflux 05:45, 11 November 2005 (UTC)

DSL repeaters do exist, such as those made by Charles Industries (HVDL products) and Versa Technology, and the now-defunct GoLong system by Symmetricom. These are digital systems requiring a relatively high voltage sourced either from the installation location, or from a separate copper wire pair dedicated to carrying power. GoLong failed because of several technical reasons. Charles Industries' HVDL product is moderately successful and suited for deployment on single lines. Ultimately there has to be a well-understood cost/reward relationship for any phone company to deploy equipment on single lines.

An approach better suited for mass deployment are Phylogy, Inc.'s TripleStream Line Conditioner products. TripleStream takes a different approach from the ones above, allowing for deployment of multiple lines with one truck roll. Phylogy uses an analog approach, power consumption is extremely low per line, providing the ability to power the unit directly from -48V POTS power without affecting normal POTS operation.

Phylogy also has ADSL2+ products and claim to provide a VDSL2 product in 2007. 23:28, 15 January 2006 (UTC)SSD

PPPoE, PPPoA[edit]

The articles states:

Many DSL technologies implement an ATM layer over the low-level bitstream layer to enable the adaptation of a number of different technologies over the same link.

If I understand correctly, this is the ATM layer referred to in PPPoA, in which case it should read "ATM or Ethernet layer," seeing as PPPoE is more common in the US. Can someone verify this?

Scorpiuss 18:55, 14 December 2005 (UTC)

I believe that ATM is the transport over DSL whether PPPoA or PPPoE is used. These protocols are ways to establish point to point serial connections and refer to the interface that PPP talks to. In PPPoA, the PPP part happens in the modem which is ATM and is before encapsulation of Ethernet has occurred, hence the name I suppose. Snafflekid 22:11, 14 December 2005 (UTC)

Inventors of DSL[edit]

DSL was originally invented in 1988 by two Bellcore research managers: Charlie Judice and Ray Laane and by one marketing manager, Emanuel Klein, from NYNEX which is now part of Verizon. HDSL had already been developed as a technology replacement for T-1 carrier which was used by the telcos for provisioning DS1 service --- a full duplex service. It was our observation that the primary applications for a residential service (video-on-demand and internet access) did not require a high bit rate upstream signal. Furthermore, we understood that in order for a residential DSL service to make sense it had to work on one pair of wires. Within a day with the help of a Bellcore engineer, Joe Lechleider, we demonstrated that an asymetric service called ADSL was possible.

I translated the German HDSL article and linked it here, to DSL. Please revise and edit to fit American nomenclature. Justin 05:33, 22 June 2006 (UTC)

question from a dialup user : Distance Limitations[edit]

from the way this is worded, it seems that anyone with a phone line can use DSL.. i've been on 56k dialup since 1998, and i know virtually nothing about any form of high-speed internet. ? - Srrrrrrr 08:14, 5 January 2006 (UTC)

There's more to it than just having a phone line. Your telephone company has to (a) offer the service in the first place and (b) install special equipment in the central office nearest you that puts the service on your line. I'll take a look at the article to see if it needs tweaking to clarify that. --Blrfl Jan 13, 2006

A major reason many customers can not receive DSL is the distance from the customer to the phone company's central switching office (CO). All DSL signals lose strength and thus speed as the signal travels over thousands of feet of copper telephone wire. Many phone networks provide the facility for DSL to travel only 12,000 feet or so before the signal dies out completely. Customers within one mile of the CO could receive the maximum 8Mbps speed if the phone company allowed it but are usually capped at 1.5-3Mbps. The achievable speed decreases for customers further out from the CO.

For years now phone companies have installed equipment to provide DSL services to more customers, in the form of remote cabinets with environmentally-hardened DSLAMs and other products. As an example, SBC's Project Pronto cost billions of dollars but now provides a higher revenue stream due to new DSL customers who could not receive DSL prior to Pronto. 23:29, 15 January 2006 (UTC)SSD

The above user gives a good explanation of why exactly there is a distance limitation to DSL. Perhaps something to that effect should be included in the "Operation" section, as the explanation currently there is rather technical, which there is nothing wrong with, but it is also somewhat unclear. ("More usable channels equates to more available bandwidth, which is why distance and line quality are a factor.") 19:58, 16 February 2006 (UTC)SSD

Half duplex[edit]

I got the word from my ISPs tech support that all DSL was half duplex, so added this to the article. Usually I wouldn't trust such a source, but they've always been good. Anyhow, I could see this varying from country to country or over time, so if anybody has better information please revise.

ADSL is by definition full duplex, meaning data can be transmitted both ways at the same time. What your phone company may have tried to explain is ADSL is asymmetrical, meaning download speeds are much greater than upload speeds.

I work in the DSL business. DSL is half duplex, meaning it is either transmitting or receiving at any given time but not both. This being said the article covers HDSL as well which is symmetrical.. —Cliffb (talk) 05:04, 2 July 2009 (UTC)

Active Phone Line Required?[edit]

Is an active telephone line required? I've heard varying views. It seems to me that you could use the phone line strictly as a data transmission line without having to have phone service. Do you have to have an active phone line? The only thing I could think of that might require one would be the routing of the signal, it might not be routed unless the line was active. Anyone know? --Littleman TAMU 20:58, 29 June 2006 (UTC)

The main thing I can think of that might require an active telephone line is a phone company that demands that you buy voice service from them if you're going to get an ADSL circuit from them. This is, I think, the most common reason why an active phone line would be required in the USA; phone companies don't want you getting Internet access from some other company, getting VoIP from your ISP or some third party, and only getting the low-level ADSL ATM transport from them. I know of no technical reason why an active phone line would be required. Guy Harris 20:22, 20 August 2006 (UTC) (talk) 05:11, 13 August 2008 (UTC) For DSL to Work

No active phone line is required for its working, DSL required the copper pair to be laid    between service provider's DSLAM and subscriber end. (talk) 05:11, 13 August 2008 (UTC)
Someone added info on naked DSL to the Operation section. That's what I was looking for. Littleman TAMU 20:22, 5 September 2006 (UTC)

Move stuff to the ADSL page?[edit]

Most of the stuff on this page appears to refer specifically to ADSL; should it be moved to the ADSL page, with this page just summarizing all Digital Subscriber Line technologies and pointing users to the ADSL page fairly quickly for the benefit of those users who are curious about their "DSL" connection? Guy Harris 20:20, 20 August 2006 (UTC)

DSL vs ADSL in common language usage[edit]

I need to know if the term DSL is commonly used in the USA to refer to ADSL (I know that ADSL is technically a type of DSL; this is a linguistic question). In Europe ADSL is called ADSL. A US technical friend of a colleague of mine swears that in the US, the term DSL is commonly used to mean (by default, I imagine) ADSL. Can anyone clear this up for me? If I say DSL in the states, will they assume I mean ADSL? Thanx. Ryancolm 07:39, 21 August 2006 (UTC)

Yes. In the US, DSL is normally understood to mean ADSL. The term xDSL is normally used when inclusively referring to all forms of DSL. ClairSamoht 08:28, 21 August 2006 (UTC)
That's cause of endless discussion... I believe that, as a encyclopaedia, Wikipedia should stand by the definition of DSL as the whole family of technologies, while keeping ADSL focused on the specific technology. I see no problem on the article about DSL telling people about the popular use of DSL, I don't mind, but for the sake of clarity, people should be redirected to the ADSL entry as soon as possible. Bear in mind that there's no "xDSL" entry on Wikipedia; adding one would do no good (except, perhaps, as a redirection to the DSL article). CarlosRibeiro 18:55, 5 November 2006 (UTC)

Also on the point of naming and common use. Do you think it's worth putting in a note about the confusion between DSL and cable. So many people I talk to think that DSL is cable and nothing to do with ADSL (they get that ADSL is over the phone line). They don't realise ADSL is a type of DSL and cable is just cable. I don't know if this confusion happens as much in the US but it happens here (UK) so much

They sound dumb.  ;-) Maybe I should take a picture of my DSL connection, which is just a plain-jane telephone line (not cable). - Theaveng (talk) 18:26, 20 November 2007 (UTC)
I think it would be extremely helpful to compare DSL and cable. DSL salespeople say that due to technology that DSL can guarantee a minimum speed whereas due to technology that cable cannot guarantte a minimum. It would help to state that explicitly, whatever the truth is. Another thing is that the DSL salespeople in the past have told me that I am too far from the office to get the slowest most economical speed and that I need to pay for faster speed to get DSL. That (seems to?) contradict what this article says so if that can be clarified that will help. Finally, some practical (less technical) explanation of extending DSL service would help. If DSL is now being offered at greater distances than a few years ago then it would help for there to be something explaining that, and hopefully it can be said in less technical terms than the article currently uses. —Preceding unsigned comment added by (talk) 17:06, 11 December 2007 (UTC)
I've seen routers advertised as "DSL Router" which don't include any DSL modem and sometimes when this is pointed out to the advertiser even they think DSL means cable!! (This is in England). BrianDGregory (talk) 18:38, 22 March 2010 (UTC)

Current US Regulatory Situation?[edit]

The article states:

"When the FCC required ILECs to lease lines to DSL providers such as Earthlink, however, a move to shared-line DSL (also known as DSL over UNE) was made to avoid the need for custom installations."

My understanding is the FCC has recently removed this access requirement -- and the DSL market may be turning into local phone company monopolies?

An update on this subject is needed == and a dedicated section on the historical development of the DSL service business model (including the confusing issue of whether there is a distinction between the customer's DSL service provider and the ISP) would be very helpful.

The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the debate was move. Andrewa 05:51, 6 October 2006 (UTC)

Requested move (2006)[edit]

Digital Subscriber LineDigital subscriber line – One of Wikipedia's naming conventions is that second and subsequent words should be lowercase unless the term is a proper noun or is always or almost always capitalized. Digital subscriber line is not a proper noun, but it is frequently capitalized. However, I do not think that it is capitalized frequently enough to have the article's name be capitalized. I suspect that it is only capitalized at all because the acronym DSL is used so often. The letters in the acronym are capitalized, so people may think that the expanded version should be capitalized (see acronym and initialism), and people may also capitalize it to show where the letters in the acronym come from, as the first instance of the term is usually "Digital Subscriber Line (DSL)" and then it is referred to as DSL from then on. I have found many instances of digital subscriber line not being capitalized, including: Cisco Press, Webopedia, McGraw-Hill, Stanford Report (Stanford University), CNET, How Stuff Works and International Engineering Consortium. News organizations, which follow the rules of English to a greater extent than other organizations, frequently do not capitalize digital subscriber line. 9 out of 18 sites on the first two pages of the Google News search, at the time I am writing this, have DSL uncapitalized. 2 out of the 20 sites listed are not counted because the term is only given in a headline that capitalizes every important word and some non-important ones. I think that the capitalization of digital subscriber line is an error, as per acronym and initialism, and that Wikipedia should not repeat the mistake. Finally, it is confusing when Wikipedia chooses slightly/somewhat more popular usage over correct usage.

For consistency, I think that if the article is moved, articles which contain Digital Subscriber Line in their title should be renamed as well. — Kjkolb 11:37, 29 September 2006 (UTC)


Add "* Support" or "* Oppose" followed by a brief explanation, then sign your opinion with ~~~~


Add any additional comments

The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Modem x Router x Gateway; Narrowband x Broadband; DSL x ADSL[edit]

CarlosRibeiro 17:46, 21 October 2006 (UTC). Three discussions into one revision:

  • Modem x Router x Gateway - On the "equipment" section, I added some comments on the difference between modems, routers, and gateways. I though it was important given the previous discussion over the terms, and also given the way DSL is usually implemented.
  • DSL x ADSL - Also on the "equipment" section, there were comments that applied only to ADSL, regarding splitters, etc. I thought it was better to move part of the comments there (explaining specifics of ADSL); but I retained some of the explanation there because it's important to understand in a generic sense.
  • Narrowband x Broadband - The explanation wasn't technically correct; it confused narrowband x broadband with Shannon's limit. The best narrowband technology uses some of the same techniques that allowed DSL to get this far, specifially, multiple symbols per transition.


Removed automatic redirect from DSL --Wavemaster447 00:37, 26 November 2006 (UTC)

No, you just removed the note that says "DSL redirects here" and points to the disambiguation page. If you really want to remove the redirect, redirect instead to the "DSL (disambiguation)" page, or request that "DSL (disambiguation)" be renamed to "DSL", if you think people looking for "DSL" should be sent to the disambiguation page rather than sent to the "Digital subscriber line" page. Guy Harris 01:07, 26 November 2006 (UTC)


"However, in the 1930s techniques were developed for broadband communications that allowed the limit to be greatly pushed" <- is that date right? —Preceding unsigned comment added by (talkcontribs)

I believe the blurb is referring to DMT, which was invented by John Cioffi in 1993. [2][3] So I'm betting it should say 1990s. - Keith D. Tyler (AMA) 20:17, 20 February 2007 (UTC)
It seems reasonable to suppose that was the intention, but it's all rather vague, given the ambiguity of the term "transmission line" and the failure to detail the relevance of the Shannon Limit. I mean, obviously a relation between bandwidth, noise and bit rate is most relevant when there's a bandwidth limit, and telephone wires are seldom pushed to any hard bandwidth limit, and Gaussian noise was not prominent among the problems that had to be overcome to achieve DSL. Hmm, the Shannon Limit would be highly relevant to the bandwidth article. I must look to see if it's there.
Arguing that the date is correct, we could point out that this was the time Groupband connections became available; see L-carrier which is where I ought to mention this development. Jim.henderson 21:26, 20 February 2007 (UTC)


I've seen reference to 'U-R2' in the documentation for my ZyXEL ADSL Router, and wondered what it was. I did a quick google and the only page that came up was on the German Wikipedia. My German is practically non-existant but using Google Translation [4] I was able to judge that it is some variant of DSL. Presumably there must be some technical differences from 'vanilla' ADSL as used in the UK/USA or ZyXEL wouldn't bother to make seperate units for U-R2! Anyone know what this is, and care to add a section on it? Slothie 23:33, 8 February 2007 (UTC)

Yes, UR-2 is a specification defined by "Deutsche Telekom". Its more official name is "1TR112", where TR stands for "Technische Richtlinie" (~technical guideline). It is important that there are a lot of ADSL systems in wordwide use that differ in details and so are incompatible. When Deutsche Telekom started ADSL, they used technology from Motorola in some areas in other areas they used equipment from Siemens, both were incompatible. So DT always had to supply the right modem to the customer and replace it when a customer moved to an area with the other system. Later the market opened, resellers and other providers startet and everyone could offer DSL modems to customers, so there was a need for a standard at least notional wide. Today DT and nearly all other German providers use UR2, so you can usually use any DSL modem on any DSL line. The standard itself defines the low level protocol used (DMT), the connection jack between DSL splitter and modem (looks like Ethernet, but lower category). UR2 devices must be compatible with ISDN on the same line (Annex-B), so the lowest 32 DMT frequencies are not used to preserve spectrum for ISDN, even if the customer just has an analog line. User:Christian —Preceding unsigned comment added by (talk) 16:39, 19 February 2008 (UTC)

U-R2 itself is the name of the port at the splitter. R stands for remote for it is the distant endpoint of the line from the operators point of view. The linecard's port is named U-C2 in which C stands for central office. The technical guideline specifies what data has to be exchanged to synchronize the connection and the fixed rates that should be delivered over a specific distance to the central office (including the dampening the modem has to deal with). Furthermore it specifies how downstream power back off is to be implemented (shutting down some carriers to avoid crosstalk between lines with strong signals from an FTTC-DSLAM and weaker signals from central office), the ATM-cell for the connection between DSLAM and modem and the working parameter for the low-pass filter in the splitter (which is designed in a way that it is always possible to use ISDN on the same line). (talk) 14:19, 8 March 2011 (UTC)

Title Name[edit]

I think the first letters in the title "Digital subscriber line" should be all capitalized, i.e. "Digital Subscriber Line". Is there any special reason for the small letters "s" and "l"? HkQwerty 20:19, 17 March 2007 (UTC)

See [5] for the standard Wiki style in this matter. As it happens, the term "Digital Subscriber Line" redirects to this article, so it shouldn't be a problem for anyone. Jim.henderson 22:36, 17 March 2007 (UTC)
I know it's case insensitive to search this article. I just don't understand why Asymmetric Digital Subscriber Line and Symmetric Digital Subscriber Line are all initial caps but this article is not. -- HkQwerty 17:06, 19 March 2007 (UTC)
Ah. There we go. We have an inconsistency. What you meant to ask is, is this article capitalised right, and the other two wrong, or vice versa? Reading the applicable section of Manual of Style, I think this one is correct and the other two are incorrect, but I'd like to hear arguments the other way before renaming anything. Jim.henderson 20:25, 19 March 2007 (UTC)
In this article DSL should be a name of a unique technology, not just a bunch of lines, right? I think it's a proper noun. -- HkQwerty 17:26, 21 March 2007 (UTC)

But it is not. It started out as a unique technology, but nobody uses that one anymore. Now it is a family of related technologies, so should probably be lower case. See below. W Nowicki (talk) 19:05, 15 September 2011 (UTC)

Proposed Change for Basic 'How it Works' Summary Section[edit]

I propose the following rewrite for the summary paragraph for clarity:

DSL connections work by splitting up the frequencies used in a single phone line into two 'bands'. The ISP data is carried over the high frequency band (25Khz and above) whereas the voice is carried over the lower frequency band (4Khz and below). The user typically installs a DSL filter on each of the phones connected to the same phone line as the DSL modem. The DSL filter filters out the high frequencies from the phone, so that the phone only sends or receives the lower frequencies (the human voice). This creates two completely independent 'bands', allowing the DSL modem and the phone to simultaneously use the same phone line without any interference from one to the other.

Loriculus 19:09, 2 July 2007 (UTC)

Yes, it looks like an improvement. Fairly minor suggestions:
  • Rename the paragraph, too. It doesn't describe any part of how DSL works, except the use of different frequencies. This is not a criticism of the paragraph or of the intent; only of the title.
  • Drop the DSL self link, and the repetitive linking of DSL filter and any others. Terms should be linked at first appearance, and perhaps at some repetitions in distant paragraphs.
  • See ADSL for the fact that the spectrum is divided into three bands, not two. This is not to suggest that this article also should say so. There are reasons why articles that overlap should not go equally into detail.
  • Oh, come to think of it, the third sentence perhaps overstates the obvious, and would be equally clear to newbies without the entire phrase "connected to the same phone line as the DSL modem. Jim.henderson 23:14, 2 July 2007 (UTC)

Thanks Jim. Here is a re-write based on your suggestions:

Title: Basics

DSL connections work by splitting up the frequencies used in a single phone line into two primary 'bands'. The ISP data is carried over the high frequency band (25Khz and above) whereas the voice is carried over the lower frequency band (4Khz and below). (See the ADSL article on how the high frequency band is sub-divided). The user typically installs a DSL filter on each of the phones. This filters out the high frequencies from the phone, so that the phone only sends or receives the lower frequencies (the human voice). This creates two completely independent 'bands', allowing the DSL modem and the phone to simultaneously use the same phone line without any interference from one to the other.

Loriculus 23:43, 2 July 2007 (UTC)

There's a lot of this discussion that is specific to ADSL lineshare and not DSL technology in general. For example, splitters aren't needed unless there happens to also be voice on the line.

Recently, Phaniraj01 added this into the same section:

DSL uses PPPoA protocol between the CPE DSL modem/ router and the ISP.

However, PPPoA is just one of the protocols that are used by a DSL modem. So, it is not a correct statement. RFC1483 (or RFC2516) bridging/routing, RBE (Routed Bridge Encapsulation), PPPoA, PPPoE are common ones. I propose replacing it with this:

DSL uses a link layer protocol such as PPPoA, PPPoE, RFC1483 (or RFC2516) bridging/routing or RBE (Routed Bridge Encapsulation) between the CPE DSL modem/router and the ISP DSLAM.

Loriculus 18:36, 3 July 2007 (UTC)

I should have looked at the talk page before reverting that sentence on stylistic grounds. Anyway, now I inserted your text, but shortened it a bit and put in a title of my own of intermediate length. Feel free to re impose your own ideas, or to improve mine further. Jim.henderson 21:51, 4 July 2007 (UTC)
That looks good. Thanks Jim. Loriculus 16:40, 5 July 2007 (UTC)

How Much Faster is DSL compared to Dialup?[edit]

I came here hoping to find a definitive answer, because Verizon's claims make no sense ("21 times faster than 56.6K dialup"). My line is only 768 kbit/second. 768/56 == 13 which is nowhere near Verizon's claim. (It's even less when you consider 56K modems use compression to increase effective thoughput to ~150 kbps).) I'd like to find an actual study that's not biased by salesmanship. - Theaveng 17:37, 14 September 2007 (UTC)

Given that ADSL can run from 768Kb/s (or possibly even lower) to 6Mb/s (or possibly even higher), there isn't a single definitive answer to your question. I've gotten 1.5Mb/s; 1500/56 = 26. Guy Harris 21:33, 15 September 2007 (UTC)
When it comes to "Speed" Differences, it all depends on what DSL package you apply for, a lower costing package may seem less then the speed of dialup but you need to consider its still a broadband connection with an "Always On" connection that allows you to still use your phone to make or recieve calls The more expensive DSL packages can also give you up to and sometimes even more then 5Mb/s. I know my provider allows up to 18Mb/s downstream --MadFrenchie 19:43, 21 October 2007 (UTC)
I should have clarified I was talking about Verizon's claim about 768 Download connections. They claim 768 kbit/s is 21 times father than a ~50 kbit/s dialup, which doesn't fit the math. ' - Theaveng (talk) 18:24, 20 November 2007 (UTC)
I just came from Korea where we had XDSL (notice the big X) that ran 1Gbps upload and download on POTS. In "wired" apartments, there is 20Gbps service but it is extremely rare and not well advertised. The speed difference in DSL depends largely on your location, your provider, and if there are one or two companies who own all the phone lines and line the pockets of politicians in both parties of a bi-party system with campaign donations lest the litigation environment in that country become unfriendly to monopolies and duopolies. There is huge amounts of competition in Korea, so the Internet speeds there are much much higher and much much cheaper than what I've got in the states.Bigblair (talk) —Preceding undated comment was added at 23:46, 17 August 2008 (UTC)

Does DSL use V.42, V.44, or some other data compression?[edit]

My dialup modem uses V.44 to compress text 6-to-1 (effective throughput of 300 kbit/s) and executables like flash programs 3-to-1 (effective throughput of 150 kbit/s). Does DSL use a similar technology to squash data on the fly? - Theaveng (talk) 18:30, 20 November 2007 (UTC)

Not as far as I know, no. Perhaps in the old days when DSL was invented, logic to do such jobs at such speed was too expensive, or unimportant since files are usually small as in HTML texts, or already compressed such as pictures or self installing programs. (talk) 18:05, 26 November 2007 (UTC)
plz provide the full  information  for DSL  —Preceding unsigned comment added by (talk) 23:41, 12 September 2008 (UTC) 

Dsl user authentication[edit]

How does Dsl user authentication take place? Which device performs the per user authentication/billing? I think this point should be mentioned, it's important. —Preceding unsigned comment added by (talk) 02:59, 8 January 2008 (UTC)


this is tiffeny evans —Preceding unsigned comment added by (talk) 22:31, 18 May 2008 (UTC)

Standard Line Conditions[edit]

What are the Standard Line Conditions Required for DSL to work Properly ?
Loop attenuation
These issues required to be discussed.
output Power  —Preceding unsigned comment added by (talk) 04:56, 13 August 2008 (UTC) 

I'm new to Wikipedia and editing, but I disagree strongly with the "inventors" section[edit]

Here's what I know. The basic underlying dual AF/RF band technology of DSL was invented by a small group of engineers who founded a spin off of Vector Graphic Corp called "Telegence" to exploit it in late 1982. They had developed the first commercial unshielded twisted pair LAN at Vector Graphic (using existing office phone wiring) for PC's called "Sabernet" and went on to successfully test adding analog office phone voice pass thru to the LAN wiring. Not the other way round as AT&T later investigated.

Telegence quickly switched to adding data to the usual office "star" phone wiring and then widely announced, published, demonstrated and shipped product and finally filed defensive US patent #4,785,448 in 1987, just over a year before AT&T Labs filed their first patent on the subject. Due to the then hidden status of pre-approved patents, AT&T presumably missed seeing the publicity and prior art and filed their very similar claims in patent # 4,924,492 about 14 months later. Professor Cioffi's pioneering encoding work much later on improving longer distance ADSL transmission, onlyapparently looked as far back as referencing the AT&T patent and subsequent publicity. Hence the commonly held belief that AT&T were the inventors of DSL. Telegence only survived until 1988, due to the focus only on the much slower ISDN by the then phone companies and stiff competition in the LAN market from Synoptics, whose forerunner of 10BaseT "Lattisnet" product claims were based on the use of existing office phone wiring, although of course it did not work over actually in use voice lines.

I would like to share this input for any discussion nedeed prior to updating the wiki page with the correct information. —Preceding unsigned comment added by PE1000 (talkcontribs) 20:46, 9 November 2008 (UTC)

Well a citation to a reliable source would be good. I did find the patent online, so will add that. W Nowicki (talk) 19:15, 15 September 2011 (UTC)

Requested move (June 2009)[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was not moved. Moving all others listed to uncapitalized titles. Jafeluv (talk) 11:39, 1 July 2009 (UTC)

Digital subscriber lineDigital Subscriber Line — Otherwise the pages below should be changed
Asymmetric Digital Subscriber LineAsymmetric digital subscriber line
High bit rate Digital Subscriber LineHigh bit rate digital subscriber line
High bit rate Digital Subscriber Line 2High bit rate digital subscriber line 2
ISDN Digital Subscriber LineISDN digital subscriber line
Multi-rate Symmetric Digital Subscriber LineMulti-rate symmetric digital subscriber line
Rate-Adaptive Digital Subscriber LineRate-adaptive digital subscriber line
Symmetric Digital Subscriber LineSymmetric digital subscriber line
Single-Pair High-speed Digital Subscriber LineSingle-pair high-speed digital subscriber line
Very High Bitrate Digital Subscriber LineVery high bitrate digital subscriber line
Very High Speed Digital Subscriber Line 2Very high speed digital subscriber line 2
-Quest for Truth (talk) 16:00, 18 June 2009 (UTC)


  • I would prefer to move the others. Wikipedia generally prefers lower case, and this does not appear to be a proper name. Septentrionalis PMAnderson 19:30, 18 June 2009 (UTC)
  • I tend to agree. These don't seem to be proper nouns, therefore we shouldn't capitalize them as if they are. -GTBacchus(talk) 19:53, 18 June 2009 (UTC)
  • Move this one. DSL is an acronym. (talk) 20:10, 18 June 2009 (UTC)
    • How is that relevant? Does anything that's referred to via an acronym attain proper noun status? -GTBacchus(talk) 20:35, 18 June 2009 (UTC)
      • I have always thought it to be a proper noun, all of them. See Talk:Single-Pair High-speed Digital Subscriber Line. A good analogy is Internet vs. internet. Internet is a proper noun, internet is not a proper noun. Most people using the word internet, however are using it to refer to the Internet, a proper noun. High-speed is not a proper noun, Single-Pair is. There are many digital subscriber lines (this POTS is one), only one Digital Subscriber Line. See HkQwerty 17:26, 21 March 2007, above. Note also, that in High bit rate Digital Subscriber Line 2, DSL is a proper noun, high bit rate is not. (talk) 14:55, 19 June 2009 (UTC)
        • I think the difference with "Internet" is that it's "the Internet", i.e. there's only one of them. Oli Filth(talk|contribs) 16:06, 19 June 2009 (UTC)
          • Yeah, there's not just one "Digital subscriber line". It's a type of thing, not a particular thing. -GTBacchus(talk) 18:48, 19 June 2009 (UTC)
            • Yes, a digital subscriber line is a type of thing, but no one ever calls it that. When anyone says digital subscriber line they are talking about only one thing, DSL. Theoretically any old telephone line that has a subscriber who is using it for digital purposes is using a digital subscriber line, but it isn't called a dsl, it is called a POTS line, for Plain Old Telephone Service (which by the way is not a proper noun). DSL certainly is a particular thing and certainly is a proper noun. (talk) 19:53, 21 June 2009 (UTC)
  • Move the others; like most technical initialisms, these aren't proper nouns. Oli Filth(talk|contribs) 21:15, 18 June 2009 (UTC)
  • Not proper nouns, so no need to capitalise. Support moving the others. Knepflerle (talk) 23:24, 18 June 2009 (UTC)
  • I agree to move all the other articles to lower-case versions of themselves — `CRAZY`(lN)`SANE` 06:11, 28 June 2009 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Improper closing[edit]

As soon as the backlog is gone at WP:RM a request to reverse the move from Digital Subscriber Line to Digital subscriber line will be introduced. It is simply false to not call DSL a proper noun. This was the only article that was incorrectly named, not any of the others. (talk) 14:45, 1 July 2009 (UTC)

I don't think it matters much how large the RM backlog is. If you feel the move was inaproppriate, go ahead and file the request, and hopefully we'll get more people to comment on the issue. My position in the matter is that reliable sources use both the capitalised (see Encarta) and the uncapitalised form (see Britannica). Furthermore, many writers capitalise the first letter of every word when acronyms are spelt out, even when the phrase is not a proper noun, resulting in spellings like "Three-Letter Acronym". Wikipedia doesn't do that. Our naming conventions advise only to capitalise proper nouns. The question that remains is whether or not DSL is a proper noun. In the section above the consensus majority view seemed to be that it's not, but further discussion on the issue is definitely welcome. Jafeluv (talk) 13:10, 2 July 2009 (UTC)
Even if moving all other pages to "proper" case is the consensus, it is not enough to be meaningful. All those names appear in many different articles and they are still "improper" case. If moving pages are "correct", then why not massively edit those "mistakes"? --Quest for Truth (talk) 15:44, 14 July 2009 (UTC)
Example: Pages that link to "Asymmetric Digital Subscriber Line" --Quest for Truth (talk) 15:47, 14 July 2009 (UTC)
No need. DSL is a proper noun. The articles should all be moved back. However there are some that were at questionable titles. I don't think that anyone could argue that High Speed is a proper noun. (talk) 12:50, 19 July 2009 (UTC)

Requested move (July 2009)[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was not moved. No change from previous move discussion, kept open for almost 2 weeks, which had a clear consensus, reaffirmed below.--Fuhghettaboutit (talk) 13:13, 26 July 2009 (UTC)

Digital subscriber lineDigital Subscriber Line — Proper noun - there is only one.
Very high bitrate digital subscriber lineVery high bitrate Digital Subscriber Line
Very high speed digital subscriber line 2Very high speed Digital Subscriber Line 2 - (talk) 04:49, 19 July 2009 (UTC)


Feel free to state your position on the renaming proposal by beginning a new line in this section with *'''Support''' or *'''Oppose''', then sign your comment with ~~~~. Since polling is not a substitute for discussion, please explain your reasons, taking into account Wikipedia's naming conventions.
  • Support Benklop (talk) 06:15, 19 July 2009 (UTC)
  • Oppose There are millions, every subscriber has one; consequently this is not usage. Septentrionalis PMAnderson 18:58, 19 July 2009 (UTC)
    • There are millions, well two at least that I can think of, and a dozen that we have articles for, even though I have never heard of them, and I'm using one, but the one I am using is more commonly called "dial-up" and is not the subject of this article. Oh wait, I just remembered a third - ISDN is also a digital subscriber line. It's like the difference between sun and Sun. If you use lowercase sun you are referring basically to any star, if Sun then only our star, the one in our solar system. If you think that proper nouns only apply if there is only one of them as in only one ship called the Queen Mary, it also applies if there are millions of copies of them, as in MS Word, for example. (talk) 15:19, 22 July 2009 (UTC)


Comment: this request should be removed. A similar request was just done in June 2009 and failed. — \`CRAZY`(lN)`SANE`/ (talkcontribs) 04:54, 19 July 2009 (UTC)
Not. The move in June was closed improperly, and there are valid reasons for the article being moved to Digital Subscriber Line. None of the other articles should have been moved. They all look really funny saying digital subscriber line. (talk) 12:10, 19 July 2009 (UTC)
Although I disagree with's view that I closed the move improperly (take a look at the discussion and you tell me what the consensus was there), I don't think this request should be removed. The issue could use some more opinions since it affects such a large number of articles. Jafeluv (talk) 06:05, 21 July 2009 (UTC)
The vote above was 4:1 in favor of moving, but I believe that the one vote opposed was the only correct vote, as in provided a correct reason. I do not believe that anyone who has worked on any of the articles affected has participated in the voting, and as such the votes were not very well informed. (talk) 15:27, 22 July 2009 (UTC)
There were five people explicitly supporting the move, four of which based their arguments on "they are not proper nouns". The only editor arguing for the then-current title said that it's an acronym (which would be a reason for capitalizing "DSL" but not a reason to capitalize "Digital Subscriber Line" per se), and later added that "they are proper nouns". (I'm assuming here that the .88 and .99 IPs are the same editor - correct me if I'm wrong.) The nominator could be counted to oppose the move (since their original nomination was in the other direction), but they didn't give any reasoning for their position and rather seemed to just lay down two different options. Now, as for the sole opposing opinion being the only correct one: Our definition of proper noun is "nouns representing unique entities, as distinguished from common nouns which describe a class of entities." It could definitely be argued that DSL is not a unique entity, but rather a class of entities which has subclasses (like ADSL, HDSL, etc.) and instances (like the service you or I are using). Of course, this proper noun vs. not proper noun thing is kind of a red herring, because we don't really care about "correct" usage, but rather about common usage. Evidence of common usage wasn't presented by either side of the debate, though, and the closing editor has to go with the arguments that are presented instead of the arguments that "should" have been presented. I do hope that we can find a solution in this move discussion which both sides find acceptable. Jafeluv (talk) 07:05, 23 July 2009 (UTC)

I would suggest finding out what any of the people who have worked on the articles think. (talk) 18:59, 24 July 2009 (UTC)

I requested the move in June. When I notice the inconsistency in capitalization, at first I felt confused. So I tried to be "neutral" and hoped that it could raise concern and encourage discussion. The sudden closing and massive moves of the other articles is out of my expectation. --Quest for Truth (talk) 03:56, 25 July 2009 (UTC)
You did the right thing. It was pretty clear that at least one of the pages had to be moved anyway. However, usually move requests stay at Wikipedia:Requested moves for 7 days, after which they are closed; this one was open for 13 days, so I don't see why you think the closing was a sudden one. Jafeluv (talk) 11:48, 25 July 2009 (UTC)
  • Do not move. The list of requested page moves above shows that there are that many classes of digital subscriber lines. It is not Wikipedia practise to capitalize a generic noun merely to Make It Look More Important. Anthony Appleyard (talk) 10:03, 26 July 2009 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Still a proper noun[edit]

I notice the comment that "The list of requested page moves above shows that there are that many classes of digital subscriber lines". That, however, does not keep it from being a proper noun. For example, there are many Star Wars movies, but that does not make it not a proper noun, as well. (talk) 20:03, 29 July 2009 (UTC)

Major improvements - How do we get together a complete description of the protocol stack?[edit]

How do we get together an overview plus complete description of the protocol stack? Can we recruit volunteers to help with this, and make a list of what is needed to go in it?CecilWard (talk) 18:33, 22 October 2009 (UTC)

"Obsolete" edit war[edit]

Please discuss and reach consensus instead of wasting time on an edit war. If you read the blog posting, the comment really just was that much of the installed base of DSL as implemented by AT&T is going to need to be replaced with other related technologies. For example, it mentions U-verse, which actually uses a variant of DSL in many cases for the last hop (Fiber to the Node). So putting it in the lead without explanation seems very misleading. Perhaps a compromise putting the quote in context further down in the body would be a good idea anyway. I am back online but have a backlog so might take a few days, or someone else can give it a try. W Nowicki (talk) 23:19, 11 September 2011 (UTC)

Requested move[edit]

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the move request was: page moved per discussion. - GTBacchus(talk) 06:42, 20 September 2011 (UTC)

Digital Subscriber LineDigital subscriber line

Per WP:CAPS and WP:TITLE: this is a generic, common noun, not a propriety or commerical term, the article title should be downcased. Matches the formatting of most related article titles. In particular, WP's house style says not to capitalise just because an abbreviation is in caps (DSL). Tony (talk) 11:56, 12 September 2011 (UTC)

  • Support I can see arguments either way, but it looks like the previous discussions in September 2006, June and July of 2009 all had good arguments for lower case, with only unsupported assertions for upper case. This is the overall article on the family of technologies, with the other more specific articles with upper case letters for the specific standards (or family of closely-related ones). It perhaps started out as a proper noun when there was only one standard, but there are so many now that it has become generic, even if it still is used as an acronym (which is not a good reason to keep the upper case). The latest move to upper case in January 2010 was done without any discussion I can see, so if anything else this could be justified as reverting that move until a true consensus is reached. The move comment was " it is a standardized technology..." but do not see that as precisely correct. The I.120 standard might have started out as the standard, but there were many that used DSL-style modulation techniques that were actually not "standard", such as, say, Long Reach Ethernet. W Nowicki (talk) 18:24, 12 September 2011 (UTC)
  • I agree. Digital subscriber line is the name of a technology, but I don’t really think it is a proper noun. Vadmium (talk) 05:41, 13 September 2011 (UTC).
  • Support – WP style is to capitalize only proper nouns. Dicklyon (talk) 03:29, 14 September 2011 (UTC)
  • Support, or more to the point, revert out of process move that unilaterally bucked the two previous discussions. Since I closed the last, I should not close this one, but since no one ever presented any evidence from reliable sources in any of those discussions: I just checked the first 100 Google News Archive results for <"Digital subscriber line technology"> (I used that form to try to isolate results from running text rather than headlines) and found that 71 used lowercase and 29 used title case.--Fuhghettaboutit (talk) 00:42, 20 September 2011 (UTC)
The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Dubious "Synchronous" -> symmetric?[edit]

There are also SDSL (Synchronous Digital Subsriber [sic] Line) and IDSL (based on ISDN).

IDSL is mentioned later, but SDSL refers to "symmetric" DSL. I do find several dubious quality books and web sites that refer to it as "synchronous" but then describe symmetric DSL. That is, they seem to be technical mistakes. W Nowicki (talk) 18:33, 15 September 2011 (UTC)

Nowicki, you could be bold and fix these, or wait for a few days to see if anyone objects here. Tony (talk) 03:42, 16 September 2011 (UTC)

Hi Bill. This book seems to suggest that it's symmetric because it's synchronous. Plausible, but I don't think it's correct. Dicklyon (talk) 05:39, 16 September 2011 (UTC)

IP-DSL—what is it?[edit]

The commercial service from AT&T branded as "U-Verse" appears to involve a DSL technology called IP-DSL. Subscribers who had DSL service (provisioned with, say, a Siemens SpeedStream 4100) may upgrade to U-Verse, but need to be provisioned with, say, a Motorola NVG-510 or Motorola 2210-02-1ATT, because the Siemens does not work with U-Verse. This report, dated 2012-05, is consistent with my own experience (albeit my switchover, in 2011-11, was “forced”).

I wish this article to contain information about the IP-DSL technology. Would such an addition be appropriate? I have not been able to find clear information about IP-DSL as yet, sorry, but would be happy to add it when I learn enough about it to make a contribution. Respectfully, ArthurOgawa (talk) 18:49, 6 September 2012 (UTC)

After consulting today with an AT&T technical support representative, it appears that U-Verse is ADSL2+, and that their ADSL2+ is “layered on top of IP-DSL”. It is still not clear whether the term IP-DSL is simply a marketing term, like U-Verse. Perhaps IP-DSL simply means the use of a IP DSLAM in the central office? ArthurOgawa (talk) 20:46, 6 September 2012 (UTC)

Why distance makes a difference in bandwidth[edit]

This article mentions in at least two places the phenomenon that DSL service over copper pair is limited by distance. E.g.:

(the higher frequencies used by DSL travel only short distances)


The line-length limitations from telephone exchange to subscriber impose more restrictions on higher data-transmission rates.

The reason is given:

The location of the DSLAM depends on the telco, but it cannot be located too far from the user because of attenuation, the loss of data due to the large amount of electrical resistance encountered as the data moves between the DSLAM and the user's DSL modem.

The latter gives something of a misimpression to the reader of what is actually occurring.

The relevant physical phenomenon is dispersion, which attenuates and phase-shifts the higher-frequency components of the signal more than those of lower frequency. This effect finds its source in the skin effect, and would exist even if the electrical conductivity of the wires were higher (but, anyway, you can't beat copper in this department).

Because the higher-frequency components in effect suffer greater attenuation than those of lower frequency, the bandwidth is lower in a longer transmission line than in a shorter. The presence of distortions in the transmission line (leading to reflections) will independently limit the effective bandwidth of the line, but a longer line is statistically more likely to have such defects than a shorter. In the end, the farther the subscriber is from the central office, the smaller the bandwidth, just as the article states, but not for the stated reason.

In my view, it is not Shannon's theorem (which relates bandwidth to the signal-to-noise ratio) that is the source of this relationship. Instead, it is the inevitable consequence of dispersion in a transmission line involving electrical currents (a copper pair is an instance of a TEM-mode transmission line). Shannon's theorem instead enters the picture by determining what amount of attenuation will, in effect, make the signal useless (i.e., data are lost).

I wish this article to better reflect the physics of the copper-pair line, but I can see that this would be difficult to do, because the phenomenon is a bit abstruse. Still, it is definitely not a simple matter of the ohmic losses in the conductors or of Gaussian noise. These latter phenomena would cause all the data to be lost once the line was too long; what happens in practice is that the useful bandwidth is gradually diminished as the line is extended. In theory, a sufficiently long copper pair would be useful only for voice transmission (4kHz bandwidth).

In my own service area, AT&T will agree to provide DSL service only to a subscriber within 14000 feet of the DSLAM, probably reflecting the distance at which the bandwidth is pushing 700kb/sec.ArthurOgawa (talk) 20:04, 6 September 2012 (UTC)

New Template of DSL Topics[edit]

I am currently developing a DSL navbox in my sandbox, User:The Quirky Kitty/sandbox. Since the current pages about DSL and its versions are a mess, I am wondering if people would support this being added to the pages related to DSL technology, instead of the {{DSL technologies}} template. I would like to know whether or not this a good idea and what should be included in it. I also would like to invite others to help me and edit it.

Its formatting is currently messy because I'm working on adding links rather than making it look good right now. The Quirky Kitty (talk) 20:12, 24 December 2012 (UTC)

I am planning to start adding this to pages on or after December 31, 7 days from the date I announced this, given that nobody objects. The Quirky Kitty (talk) 03:26, 28 December 2012 (UTC)
Also, I plan to put it at Template:DSL when I begin transcluding it into DSL articles. The Quirky Kitty (talk) 03:39, 28 December 2012 (UTC)

Your's looks nicer than {{DSL technologies}} but they both have the same links. Why do you think we need a new template as opposed to improving the existing one? -—Kvng 16:01, 31 December 2012 (UTC)
I am sorry that real life has gotten in the way, and it has taken so long for me to respond, but I think we need a new template because the one I made is degned to be put at the bottom of the page, as opposed to the top. Which is better? — Preceding unsigned comment added by The Quirky Kitty (talkcontribs) 23:03, 7 April 2013 (UTC)
Forgot to sign. Sorry. The Quirky Kitty (talk) 23:06, 7 April 2013 (UTC)
I have just changed Template:DSL technologies to a navbox, and was not aware of this draft work until now. It would probably be a good idea to merge the two. See also Template Talk:DSL technologies Conquerist (talk) 13:14, 14 February 2014 (UTC)

First sentence: DSL [uses] a local telephone network which uses the public switched telephone network?[edit]

At the risk of revealing that I don't know what I'm talking about...doesn't DSL just use the line up TO the CO's DSL modem? DSL exists only on the local loop, and simply delivers data to the PSTN.

So the first sentence, " a family of technologies that provide internet access by transmitting digital data using a local telephone network which uses the public switched telephone network" might better read " transmitting data to the public telephone network over a [subscriber line | local loop]". And does it have to be "internet" access? Or even PSTN access, for that matter.

I would also take "switched" out of PSTN; I think "switched" referred to switched circuits, as opposed to switched packets.LiveYankee (talk) 05:54, 3 November 2014 (UTC)

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