Kitz Forum
Broadband Related => Broadband Hardware => Topic started by: tickmike on November 26, 2014, 12:36:17 PM
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Did I read somewhere that you should 'Power Off' your Modem/Router than just un-plugging your DSL line when you are changing the Modem/Router configs.
If so is that use the 'power switch' or un-plug the mains lead ?
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It's certainly best to power down the modem, and I can't see that it makes any difference which way you do that.
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BT's systems can't distinguish between a reboot/power down or loss of synch I was told.
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BT's systems can't distinguish between a reboot/power down or loss of synch I was told.
The linecard can. Whether BT's management systems can is another matter. Sky's can.
Edit - noticed simon's sig. The reference to Sky's management systems is for ADSL, obviously we're all in the same position on VDSL (FTTC).
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The best practice would be to power off the modem, thus allowing it to send a "dying gasp" to the DSLAM/MSAN. Then remove the WAN link cable and power the modem back up for any configuration adjustments.
Whether one rigorously follows the above will be directly related to one's experiences! ;)
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The best practice would be to power off the modem, thus allowing it to send a "dying gasp" to the DSLAM/MSAN. Then remove the WAN link cable and power the modem back up for any configuration adjustments.
Whether one rigorously follows the above will be directly related to one's experiences! ;)
Sounds good.
Re "dying gasp" ! so does this get produced when the power supply volts decay quickly either by pushing the power switch or unplugging the mains supply , it then sends this "dying gasp" signal. :hmm:
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My understanding of the "dying gasp" is that the device will generate such a signal when the operating voltage falls below a defined minimum.
I'm sure I read in some Beattie documentation (possibly in one of her SINs) about the relevant tests which a modem should pass to be certified as appropriate for use on her network.
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I have been doing the following procedure if I need to reboot modem.
cut the power to modem
give at least 30 mins
power the modem up
I have never been DLM'd from doing that.
Likewise when I Swapped to the billion.
power off old modem
configure the new modem (billion in this case) with it "disconnected"
power off the billion after configuring and connect it up
make sure at least 30mins have passed
power up the billion
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Kitz's info suggested that the DLM uses 15min blocks and does not count a friendly error code disconnect (best to power off) if it is followed by a 15 min with no connection.. i.e. off for 30min. Chrysalis is consistent with that.
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I think it does matter & i think the cabinet can detect the kind of disconnection ... but not sure what is the right way to do ...
example with the broadcom modems there is retrain reason 1,2,8,4000, 8000, 40000 etc ... i am sure is something similar to the cabinet
http://forum.kitz.co.uk/index.php?topic=12504.0
or i am wrong?
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The DLM checks the line every 15 minutes, and as we don't know the exact time the DLM last checked your line so we need to use the 30 minute powered off state to make sure it see this on the next check.
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Whilst most routers are capable of sending a dying gasp message, and the DSLAM may record the code...... BT deemed several years ago for various reasons that the dying gasp message was not a reliable method for detection of an unforced retrain.
BT's DLM system does NOT take a blind bit of notice of dying gasps - it has its own system to detect what it calls Unforced retrains.
See ~ Detection of sync events (http://www.kitz.co.uk/adsl/DLM.htm#dlm_sync_events) & Unforced retrains (http://www.kitz.co.uk/adsl/DLM.htm#unforced_retrains)
Whether BT's system of detecting unforced retrains is more reliable is up for debate, because it only assumes unforced if the EU has a full 15min bin with 0 uptime.
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But it is still good practice to ensure that a "dying gasp" is sent. Especially as Beattie is not the sole, monopoly, ISP/CP! ::)
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I totally agree.. and note my mention if I think their method is actually more reliable or not.
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BT's DLM system does NOT take a blind bit of notice of dying gasps - it has its own system to detect what it calls Unforced retrains. .....
Whether BT's system of detecting unforced retrains is more reliable is up for debate, because it only assumes unforced if the EU has a full 15min bin with 0 uptime.
Thanks for a definitive statement. I'll see if my local BT follows the rules !
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Ive been preaching about dying gasp now for years. Many many years ago (8-10yrs) you'll find I was one of the first who was saying that you must not ever pull the modem cable because that stopped a dying gasp message from being sent. Most people back then didnt even know what a dying gasp was. I am well aware that its there and that these days most routers do sent it.
Going back about umm 6/7yrs? and certainly during the period about the time when maxdsl was first introduced, not all routers sent a dying gasp message. Whether that is the reason why BT developed their own system of detecting unforced retrains Ive no idea. But for whatever reason in 2009/2010 BT changed the DLM to also detect errors and the method in which they detected unforced retrains.
Ive been harping on for a couple of years that BT 21CN/FTTC DLM takes no notice of dying gasp, but I feel like Im fighting a losing battle. :(
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Since BT and patents are so much in the news atm.
Heres (http://www.google.com/patents/WO2008093045A2?cl=en) the 2008 BT patent which they 'invented' and the method they use to detect resyncs for DLM
"Instead of relying on a DSLAM detecting the occurrence of a resynch event at the DSL connection layer, a higher or lower layer protocol could be used such as detecting that the ATM connection has gone down and/or come back up again, or detecting that a RADIUS transaction has occurred in respect of the corresponding DSL connection".
The BT DLM doesnt count loss of syncs, it doesnt count the number of times that the connection drops. Its not interested in power offs.
Instead its more interested in when retrains occur which is when the line comes back up. These are detected at the RADIUS not the DSLAM. By using this method the DLM can also detect failed initialisations. It assumes that if a line has lost sync through low SNR or bit errors, that the modem will automatically attempt a resync... and thats what its on the look out for.
I can guarantee you 100% that the BT DLM is only interested in the following as far as resyncs are concerned:
Unforced retrain count
Full Initialisations
Failed initialisations
and I repeat for the zillionth time it doesnt care about the line being dropped, how its been dropped, when its been dropped or dying gasps.. it only cares about resync attempts.
But just to make it really simple and to understand the difference and why it takes no notice of dying gasp: - It counts sync UP events not sync DOWN events.
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Kitz how sure are you that the ADSL DLM is been used for FTTC?
I have never been on 21CN BTw adsl, I moved from 20CN adsl to VM cable and then back to FTTC.
On 20CN DLM did not force a resync to action its settings, instead it just waited for the modem to resync for other reasons. So my experience of DLM on adsl to FTTC is hugely different suggesting a lot of changes have been made, and of course we know FTTC DLM doesnt even use snr margin adjustments. So the question is what are the differences between 21CN adsl DLM and FTTC DLM? FTTC is also PTM not ATM.
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Ok this is it. Im done. I keep repeating the same things over and over but if no one believes that theres any truth in what Im saying then Im totally wasting my time. Ive spent 100's of hours researching DLM over the past few months. So this is my final post about it because I feel like a stuck record. :wall:
Its the same system. It has 3 separate subsystems :- FTTC, 21CN, 20CN.
The functions are the same, but they have different parameters.
ie the MTBE trigger parameters can be different or
the configuration parameters can be different ie SNRm or banding.
the FTTC ILQ timing can be different in order to remove the above parameters.
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Kitz there is some major differences to 20CN tho hence my question.
Seems you got out the wrong side of bed today.
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Maybe I am gumpy as I have a post op infection and feel like crap, but that aside, even before today I was beginning to get fed up of repeating myself in the other thread and no-one taking any notice. It had started to become evident way before today (http://forum.kitz.co.uk/index.php?topic=14598.msg274634#msg274634) that I was wasting my time posting about some of the stuff. I am not into the habit of putting up duff info on the main site. If I dont know stuff I say I dont know (http://forum.kitz.co.uk/index.php?topic=14598.msg275211#msg275211) and I wont bullsh!t people.
The reason why its taking me so long to complete the pages is because the topic is huge and there is so much info, yet it can take hours of reading just to find one bit of info that you want. Ive explained to you in PMs I cant give proof for some of the info I have because some of it is behind paywall, some of its marked confidential, some of it is whitepapers Ive paid for. I will also not disclose some sources of info because that would just close a door in future. Its not in my interest to make up garbage. Im doing this so we all have some more info.
Ive even told you guys the areas which I dont have info, but some of it is trickling though. Its one big massive jigsaw.
Of course there's differences between 20CN and FTTC - but the DLM system is separate hardware and software, its in addition to DSL. Its a system that runs alongside the existing technology. It doesnt matter if the DSL uses ATM or PTM & it doesnt care how traffic is routed thats not what its there for. Its a system that collects information from the DSLAMs, RAMBO calculates what it should do, the Element Manager configures the DSLAM, with whatever parameters you want to configure.
Its the Element Managers job is to ensure that all technologies, DSLAM manufacturers, and the DSLAM's OS can all interact with the one OSS. The Element manager takes the instruction from DLM and sets the correct parameters. Read up on Element Managers (http://www.kitz.co.uk/adsl/DLM_system.htm#element_manager) and you'll see what I mean and what their purpose is. Its specifically why I had to research the DLM system and put a page up on that before I could even begin to start on the DLM functions.
Look at it this way. Java programs will run on Linux, Windows etc, the hardware will also be different. Yet the same program will run on all systems. Think of the Event Manager as performing all the translation between the OSS, the DLM and the DSLAM's O/S
ASSIA has a DLM product that can be run on FTTC or DSL or whatever. Its the Vendor specific Element Managers do all the talking to the DSLAMS. Their system runs on all products, again not caring if its LLU or whatever.
You asked what the differences were, Ive already gone over this before several times. I am aware of (most?) the differences as you can see where Ive got up to in my research here (http://www.kitz.co.uk/adsl/DLM.htm#DLM_profile_changes). Ive mentioned the doubler and the ILQ several times, Ive mentioned that is the area Im currently researching and its not something I wont talk about until its all straight in my head enough to put in print. Its this function that is different.. when I have all that info together... then and only then will I talk about the ILQ/doubler function because thats the function that controls when the DLM makes steps backwards and downwards and does the stuff like removing interleaving etc.
I am specifically researching the FTTC algorithms, and 21CN is much easier to find info about, but its FTTC Im after.
Although I originally had profiles up on that page, they have been moved out to another new page (not yet uploaded) which will show the differences at a glance on one single page.
Yep Im peed because Ive had to struggle explaining every god-damn point of DLM, whether it be one system, the use of MTBE, the fact that FECs are ignored, dying gasp, wide area events, unforced retrains, 15 min monitoring, normalisation of the days events. I got peed because Im saying the same stuff over and over. I dont know of anyone that has attempted to go into the DLM nor spent the time researching in as much depth as I have. I appreciate that Im bringing new terms and new technology into the conversation and functions that no-one has heard of before, but if someone wants to spend several hundred hours reading through all the stuff that I have trying to pick the meat from the bones.. then be my guest, because Im not going to waste time any longer justifying what I do.
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Edit MTBE typo
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Well put Kitz.
Is this immense (and I mean immense) topic, worthy of it's own header under the main menu options ?? There seems to be lots of different convo's on different threads basically talking about the same thing.
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I thought I only ask a simple question. :blush:
Thanks for the info very interesting. :)
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I actually did read the pages in question, but I think talking down to people when they dont have the privilege of having access to the documents you have is wrong, you said a reason you created this site is to get away from the atmosphere of tbb, I hope you get back to what seems was your old self. People inevitably on a forum will ask questions, and yes it may be repeated questions.
Regarding my question I wasnt asking if there is all separate hardware kit for 20CN but more so if its a separate DLM software package. As the differences from 20CN DLM to FTTC DLM is more than just different parameters, it behaves very different and isp's have different interfaces to it.
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Locked by request of OP.