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Author Topic: ADSL Max questions  (Read 2229 times)


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ADSL Max questions
« on: December 08, 2006, 04:04:21 PM »

Hi, I was wondering if you could help me with a few questions. My main problem is with DLM, I've read so many descriptions and there seems to be a variety of interpretations. My own ISPs help pages contradict themselves many times. One ISP seems to think your line rate is held between the MSR and the fault rate, only they are alone in this.

Anyway where I am is stuck on 1500k.

My line came on Friday, I'm not sure how fast it was running, I didn't really check. It had disconnected a few times over the first 3 days, syncing mostly at 8128, a couple at 7xxx, I think one must have been 5xxx (as ISP figure I mention later).

 On Sunday I told my Netgear to disconnect, then pulled out the phone cable while I rewired the extension cable as my router was on the end of about 30m of cable. When I plugged in the phone cable it resynced at 17xx, so I rebooted it and it synced at 15xx  :'( I realised I'd left an unfiltered phone that I was testing with, so unplugged that and powered down and up my router, resynced at 8128, noise margin about 6+db higher than prewiring. This was about 23:30, after 24 hours I disconnected, powered off for 10 mins and then reconnected (Monday night) Then I started logging at 6am as you can see from this graph of noise margin and errors. Every sync is at 8128, which can be seen as the resetting of error count, and no losses of connection.

In my ISP panel I have this:
Current Line Rate     1,728 kb/s (updated 05/12/2006)
Estimated Stable Line Rate    2,272 kb/s

Although I'm not sure what those figures are exactly. The stable line rate hasn't changed, I've seen the other start at 5xxx and then after my Sunday mission drop to 1152. On Tuesday however it jumped to it's present figure well outside of a sync event, around 6-7pm. Speed tests proved my line rate had gone up outside of a sync event. Subsequent visits to BTs tester showed my IP rate at 1500k. However this is where it has stayed, despite having one 8128 sync on 6 days running. Whats going on?

My noise margin looks fine doesn't it? It was clinging on at 1dB before re-wiring.

I was also wondering about those errors, are they within normal range? They seem to lessen off after the evening period in the night period as the noise decreases, although not so much during the day period when noise is very low.

Is there any more bang up to date detailed info on DLM? Although this site seems to be best so far, it is missing blip logic and I would like more info on the not-resyncing philosophy , maybe there is something detailed from BT?

Also while I'm here, does LLU change this, I mean do they do it the same way as BT?

Thanks for your time and any advise,



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Re: ADSL Max questions
« Reply #1 on: December 09, 2006, 10:23:41 AM »

Hi Adam, welcome to the forum. I'm afraid people are away at the moment, so the usual expertise is in short supply.

As you are still in the first ten days, I think you need to wait another few days before reaching any conclusions. It looks as though your target noise margin has been increased to improve stability, as well as interleaving being applied. If you're still consistently getting 8128 kbps sync then you should get the maximum IP profile of 7150. Your profile may be stuck at a lower figure, so if it's still at 1500 after a few more days you will need to contact your ISP to get the IP profile unstuck.

There's nothing very magic about blip logic. It simply specifies that a single low-speed resync after (I think) a week at a higher speed will be ignored, and will not cause your IP profile to be lowered.

I'm afraid I don't know anything at all about LLU.



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Re: ADSL Max questions
« Reply #2 on: December 09, 2006, 03:59:08 PM »

I was just doing a couple of speed tests, getting about 1mbs, then got 2 at 2mbs. So I went back to BT to see if my profile had gone up:
Test1 comprises of Best Effort Test:  -provides background information.
    IP profile for your line is - 7150 kbps
    DSL connection rate: 448 kbps(UP-STREAM)  8128 kbps(DOWN-STREAM)
    Actual IP throughput achieved during the test was - 2436 kbps

If you wish to discuss these results please contact your ISP.

If you are experiencing problems with specific applications, servers or websites please contact your ISP for assistance.

Your test has completed please close this window to exit the performance tester.
Sweet it's finally gone up after 5 1/2 days. Not the best throughput, but I'll test at a better time, I'm fine with it being somewhere over my old 2mb at heavy times and giving me more when there is some, at least for a while until my ISP or BT start upping capacity.
Well at least I don't have to carry on with this stupid power cycling routine which doesn't seem to do anything anyway and can just leave it on 24/7, I've just ordered a HD, so can finally get started on my media server.

From what I gather about blip logic, it comes into effect after a month, then it will stop BRAS profile from going down due to one low sync if it hadn't lowered in the previous 14 days. What I can't find is how long it can be synced at this lower speed (maybe doesn't matter) Perhaps even the server initiates a resync with the router. Also if there is a second counter, ie you are at 8128 for 3 weeks, one sync at 5xxx, then at 8128 for 3 days, your still at 7150, then another 5xxx, does the blip logic still look at the time at current profile or does it remember 3 days ago? BT need to release full details.


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Re: ADSL Max questions
« Reply #3 on: December 09, 2006, 06:26:05 PM »

Also while I'm here, does LLU change this, I mean do they do it the same way as BT?

LLU allows other communications operators into BT exchanges. The main idea is that the ISP can have their own equipment onto their own backhaul network located in the exchange rather than using BT wholesale's network.

Obviously installing their own equipment and fibre is an expensive business, so why they bother is beyond me.
Under some circumstances LLU even provides third party access to the lines themselves which is very troubling.

So whilst not actually answering the quoted question, i would expect that LLU operators probably have duplicate equipment the same as BT would use or otherwise make use of BT equipment linked up to their backhaul network. I doubt they would employ any of their own technology when they can take full advantage of BT's.

BT need to release full details.

If BT did release an official reference, they would be unindated with problems which didn't concern them from people who didn't understand any of it or would otherwise have been quite content.

BT is fairly transparent, but at the end of the day it is up to the end users ISP to mother their customers, not BT.
(No doubt the ISP's do have a proper understanding of the technology.)

Remember how broadband matters work these days and apply the same logic to information exchange - The ISP is BT's customer and you are customer to the ISP. ISPs have access to lots of systems and information made available by BT, so why not try and get it out of them  ;)

I would also expect only a very small percentage of ADSL users know what makes it tick and understand it. Most people don't even run a speedtest and the minute they have problems with drop outs they call the ISP because its all they know to do. So on that basis the effort of BT making information available publically probably isbt a high priority.
« Last Edit: December 11, 2006, 09:35:09 PM by soms »


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Re: ADSL Max questions
« Reply #4 on: December 12, 2006, 01:52:04 AM »

Your "line rate" can be called several different things but it is not the MSR or Fault threshold rate.

Once your MSR and FTR has been set after the 10 day period, then they will remain fixed unless reset at a BT engineers request.

Your line rate is actually the speed at which you sync at.
data rate/IP profile/bRAS can and will vary depending upon the lowest speed which you sync at.

Current Line Rate     1,728 kb/s (updated 05/12/2006)
Estimated Stable Line Rate    2,272 kb/s

Line rate on that will be the last info your ISP has from BT, this can sometimes be a bit behind as afaik reports are only generated daily* - therefore it can be a short while before your ISP gets to update their records. [*am willing to be corrected if any one knows otherwise]

You estimated stable line rate being set at 2272 is indicative that you are still within the 10 day training period, I would simply interpret that as being that you previously had a stable 2Mb connection.

Your stable rate wont change until after the full 10 day period..  and then your ISP will have to update their info.. so were talking 11 days minimum.

Blip logic - theres not too much info about it...  Ive got a half updated max page thats still on my todo list :/
Just about all there is to know about it though has already been covered in this thread.

LLU does work slightly differently in that LLU doesnt have IP rates/Data Rates and therefore theres no silly bRAS profiles.

Its basically their own DSLAM --> own backhaul
Please do not PM me with queries for broadband help as I may not be able to respond.
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