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ADSL Bandwidth Limiting? 21

Posted by Cliff from the how-does-it-work? dept.
axerzak asks: "Does anyone know how the bandwidth on Southwestern Bells ADSL service is limited (from the telco central switch or customer premise)? Running Linux with GTE service allows maximum throughput of 1.5 mbps even though only 384 kbps is subscribed. This leads me to believe that the service from GTE is limited from the customer premise not the central switch. Thanx for any insight."
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ADSL Bandwidth Limiting? More

ADSL Bandwidth Limiting?

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  • PacBell offers 384k/128k ADSL, however your upstream is capped at 128k(pretty standard.) If your line qualifies, your base is 384k but you can get up to, according to PacBell's page 3Mbps if you are close to the CO. I know people about a mile out that get around 1.5Mbps down. DSL speed degrades with distance so if you get more, good for you, if you don't oh well. The real limiting factor is the 128k capped uplink, I know a couple guys sharing a 384k/128k DSL line, while one is playing Tribes and the other is FTPing, the uplink becomes saturated and lag sets in pretty bad. Get SDSL where possible to avoid that. The synchronous data transfer will make your connection a lot more efficient.
  • While there may be techniques where bandwidth is limited artificially, there may be other circumstances. With my Pacific Bell ADSL line the download speed they were willing to guarantee was 384K BPS. But, if you are close enough to the switching station, and the line ran nice and clean, and the moon was in the seventh house..., you could get more; in my case i was close enough, etc., and i get about 1.5 Meg BPS. So, it's possible that the 384K quoted is a minimum; if you get more, they don't care, but they can't tell if you'll get more until it's running.

    This leads me to believe that proximity to phone switching stations will become a factor in house prices, creating areas of slightly higher prices, the same way that mass transit stations do. I know i wouldn't want to go back to anything less when i move...

    mahlen

    Why do kamikaze pilots wear helmets?
  • It's worth pointing out that many ADSL deployments seem to run ATM PVCs from the DSLAM (DSL box at the CO) to the ISP - the PCR is the Peak Cell Rate (i.e. max burst rate) that you'll get, and the SCR is the Sustained Cell Rate that defines the guaranteed minimum rate (like frame relay Committed Information Rate).

    For more information, see the ATM Forum or ADSL Forum websites.
  • this [swbell.com]

    The guaranteed speed is 384 Kb/s...

    The maximum speed is 1.5 Mb/s

    I think that it's limited on their side... probably through hardware, because everyone seems to have the same speed ratings for their services...

  • I haven't seen any of the artificial bandwidth limiting, yet... Most of the people I've heard from (mostly here on /.) seem to be getting well above the guaranteed speeds...
  • I'll be moving to Houston in about a month; it seems that SWBell and GTE are the only two telcos around that will do DSL around there. (?)



    GTE doesn't cover my new neighborhood so I'm thinking about going with SWBell and nol.net dsl service.



    I'm just posting to say anyone's opinions on GTE vs. SWBell, adsl, nol.net, or whatever would be greatly appreciated.
  • Absolutely. I'm still in the process of looking for a new apartment or house. My company is providing a sort of relocation service, and one of the items I listed was proximity to the telco's central office.
  • I have GTE and My friends in pac bell area (like one or two suburbs over) get it for half price at (guaranteed 340/128, uncapped) while i get only 128/64 :(

    bastard monopolists

    everyone goto www.handsofftheinterent.com!!!
    lets bring in some real competion!
  • I'm just posting to say anyone's opinions on GTE vs. SWBell, adsl, nol.net, or whatever would be greatly appreciated.

    A friend of mine has ADSL service through SWBell (the loop) and SWBell.net (data/ISP) and raves about it.

    I tried to get it and after a 2month wait for the install date (my date was 1 day ahead of my friend's) found out that, in fact, my neighborhood couldn't get it. Something about too many T1 and ISDN customers on that segment. I was very disappointed.

    The whole ADSL thing is under some debate. You can dig up some tidbits about it, and houston service, in houston.internet.providers.

  • I've had a few lengthy chats with folks at SWBell concerning my own, eventually failed, ADSL installation. One tidbit to come out of all this concerned how they were rationing service.

    For example, the least expensive service involves getting one single dynamic IP address. There is currently nothing in place to stop you from checking out multiple IP adresses. In fact, people are doing that right now. And SWBell is completely aware of it and are tracking it. The guy I talked to said they're not doing anything about it right now (beyond monitoring), but likely will in the future.

    A friend of mine who just got ADSL from SWBell is also getting very speedy transfers - in excess of the advertised top speed for the service he bought. I can't help to think that these two situations are linked and after the intial roll-out time is done (SWBell is still frantically running around and trying to get all this to work) they'll begin to limit service closer to what they've in fact sold to their customers.

  • 384K is actually the lowest `guaranteed' speed. 1.5 MB is the highest speed you can get downward from them on that specific ADSL configuration.
  • I have USWest RADSL with a local ISP. The first weeks of service my Cisco DSL Modem was "Trained" for, and getting, 1.5Mb/s. I only pay for 256Kb/s so I asked a USWest tech about it. He told me my ISP sends the speed my Modem should be set to, to USWest when the service was created. Then USWest sets the speed each time my modem comes on-line by sending this "Training" signal down the wire.

    I now get a solid 512Kb/s, (maybe I should have kept my mouth shut :)

  • Your bandwidth is limited via ATM PCR to 1.544Mbps if you bought the basic, 6.0Mbps if you bought advanced.

    However, since it's ATM and you get a PVC worth that much bandwidth, you'll probably find your DSL line is faster than your 8-port 100Base-TX hub workgroup hub...
  • Agreed...

    Using USWest's Megabit with an independent local ISP. The Cisco 675 has always showed the line trained at 768K down 256K up. (Paying for 256K down, 128K up). The first two weeks I was using it with my ISP it seemed I was getting throttled right down to 256K. After about two weeks the throttle became 512K. I'm not sure if that's a judicious decision by my ISP based on observing my bandwidth usage for a couple of weeks or just the way things have worked out. I don't upload enough to have measured my actual throughput that direction.

  • Well i tend to disagree with u on that
    This is why:
    If you look at how DSL technology works and tests showing the distance and hight bandwidth a stable signal can be sent over a DSL line by that ratio...it proves that any local loop qualified should easily be able to carry a full 1.5mbps data transfer rate...i for one live 2.5 miles out and most would say well you aren't going to have fast ADSL so dont expect it...maybe so but it has absolutely 0 to do with the distance to the local CO. I can prove this because swbell has tested my telephone lines thoroughly (cause im close to the 3 mile limit) and proved that a signal can be held for both the 384k-1.5mbps / 128kbps service +
    i could get the 1.5mbps - 6.0mbps / 384kbps service also...which means its all something they set. I even would go as far as to say swbell might be limiting users in a fashion that makes it look like this is occuring...shit thats good marketing on their part heeh they get more money that way an dhave to pay for less bandwidth as a provider. I would also like to add that its not true that swbell GARANTEE's you 384kbps downstream ... they say your LINE will get you 384kbps for sure...hehehe they will set the rate there for the line and also as a provider they can further restrict your bandwidth as your provider. I am soon to get DSL becasuse i want some 20 pings :) ... but im not dealing with what
    EVER SINGLE PERSON that uses the telco for internet access has to deal with... that is after a few months 150 ping jumps with 20% packet loss 15k downloading...shit i would keep ISDN over that...so im going with a seperate provider and i think if enough people do that the telco will have to rethink their strategies...

    kirkyg
  • The bandwidth throttle for DSL lines is configured on the router of the ISP. Uswest simply makes the connections. Same deal with ATM lines, etc. If you're lucky, the ISP can forget to throttle it back at all, and you'll get the full 1.5Mbps.
    Of course, USWest could be the ISP as well...
  • When my aDSL was installed I was not getting the full throughput. I paid for 384k but tests showed transfers at about 256k. I called my ISP and they said I was being correctly throttled on their end. I called GTE and they said I was throttled wrong on their end (they set me at Silver when I should be receiving Gold. A few hours later I was up to full speed, and pegged out at exactly 384k. No freeby extra bandwidth out here :(

    So in my setup (Portland, Oregon) I am definately throttled at the CO and most likely by the ISP as well.
    .......
    Choochus

  • I'm using SWB ADSL and I am sure I live fairly far ~17 kilo-feet from the switch. THe max distance is supposed to be 19 kilo-feet so I feel pretty lucky to be getting anything above 384 Kbs.

    If you have a home security system, MAKE SURE that your ADSL signal is NOT running through it. Normally, all phone lines go to the security system first and then back to the house lines so that it can preempt any calls in progress if needed to alert the monitoring service.

    In my case, before the security system was even turned on, it knocked over 240 Kbs off my line speed. Once the system was turned on, my ADSL modem wouldn't even sync to SWBells signal. (The security system seemed to also be adding about 50v DC to the line!)

    Today was a frustrating day rewiring things in an attic in HOUSTON of all places, but, in the end, I ended up "cleaning" my signal and now I enjoy about 1100 Kbs or about 120 KBs! Not bad for 17Kft!

    Good luck

  • Just as a note.. My company does ADSL Installs for World Web Internet Service Provider (wwisp.com). Having dealth with ADSL and all its round abouts and with Bell (ugh) I can surely tell you that in most cases the bandwith is limited at the ISP side. It is then limited by the telco to 1.5Mbps (at least in B'ham) by the DSLAM on the ATM circuit side. It may be different in other regions using other CO side equipment. BellSouth uses Alcatel. Hope this helps a little. Ed McLain Technology Unlimited, Inc. [tuial.com] Birmingham's Premiere Network Solutions Provider. Linux*Windows 9x/NT/2000*Macintosh
    Edward McLain
    Technology Unlimited, Inc.
    Birmingham's Premiere Network Solutions Provider
    Linux / Windows NT \ Macintosh

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