Does a re-synch always result in a lower IP Profile?

I still have not had any real answer on this.

DLM always seems to lower a IP profile. Can anyone explain how a higher synch is achieved ? (Without any user intervention, after recent experience I want to leave the modem & router on)

The IP profile reflects the synch speed, DLM influences the synch speed. Speeds can increase if the error rate reduces etc but this will take longer to recover than it took to drop in the first place as the systems are biased towards stability.

Your modem can only get to a higher speed by resynching under an external influence, whereas it will fall to a lower speed automatically if it can't hang onto the speed it is connected at.

In reply to a post by shalom2005:

DLM always seems to lower a IP profile. Can anyone explain how a higher synch is achieved ? (Without any user intervention, after recent experience I want to leave the modem & router on)

You've answered your own question- without user intervention, you have to wait for the DLM to do its own thing.

IME experience, if something causes a drop in sync and then goes away the DLM will eventually force a re-sync to a higher speed, but it takes its time about it- it's not impulsive, even if the noise is .

Still unclear!

"Your modem can only get to a higher speed by resynching under an external influence"

Can you please explain what 'an external influence' is?

(I'm happy to leave my modem & router connected now as I recently had a drop from 66-59Mbps. I'm unclear how a re-synch can occur if my connection is 'always on'. My line is very stable & can stay that way for 28 days or more.)

Thanks for your patience with my questions!

an external influence would be either you turning it off and on or asking it to resync via a user interface, or the cabinet DSLAM dropping the connection to force a resynch perhaps in repsonse to DLM changing parameters.

In other words your modem will not automatically seek a higher speed on its own account.

Ah thanks Billford. You typed at the same time as me

That's clearer. So, if DLM sees a really stable line, it will eventually resynch to the maximum the stable line can take. I just have to wait for it to do so.


Thanks guys.

Thanks Yarwell. So, the modem may not force a resynch, but the cab DSLAM will hopefully force a resynch in the future. Good that's what I was hoping.

Many thanks

In reply to a post by shalom2005:

I just have to wait for it to do so.

Yup, and be prepared for (potentially) quite a long wait, it can take weeks.

I'm not sure if anyone really knows how the DLM comes to its decisions (and I'd include OpenReach in that!), but it seems to depend on how large it thinks the improvement would be. If it's substantial then it can be fairly quick (days) but if it's only slight then it will take a lot longer.

Summary. While waiting for a DLM speed increase, reconnect the router each morning.

The IP profile reflects the synch speed, DLM influences the synch speed.

The sync speed is effectively controlled by DLM as part of the low level cabinet->modem connection. The IP/BRAS profile is established from the sync speed as others have said above.
However, this does not happen completely automatically, it only happens when the router establishes a new pppoe connection.

A change of sync speed always involves a new connection from cabinet->modem. Sometimes, as the connection is broken at the lower cabinet->modem level, the pppoe connection is lost at the higher (router->exchange) level. Once the lower level connection is reestablished at the new sync speed, the router makes a new pppoe connection and a new IP/BRAS profile is correctly established.

However, quite often the reconnection at the lower level happens so quickly that the higher level connection does not notice the drop. The pppoe connection is not broken and does not need to be reestablished, and the IP/BRAS profile remains at its previous level, matching the old sync speed. This can be resolved by manually disconnecting and reconnecting the router (not modem); preferably using the web interface, or alternatively by resetting or power cycling the router.

When hoping for a rise in speed, it is worth reconnecting the router each morning; DLM usually schedules sync speed increases overnight. The speed you see is effectively the lower of the sync speed and IP/BRAS profile. Where the new sync speed is faster than the old, you will be left with a lower IP profile which will artificially keep your speed down. Where the new sync speed is slower than the old, it will be the sync speed that limits you. Reconnection will lower the IP profile, but won't lower the speed you actually see.

There is never any harm disconnecting/reconnecting the router. The router reconnection is not seen by DLM; unlike power cycling the modem which can be seen as an error by DLM. As FTTC connections are often very stable for months at a time, you could suffer unnecessarily low IP profile and speeds for such periods after a DLM increase if you do not reconnect at the router level.

As also mentioned above, the DLM rise in speed can take two to three weeks; DLM is very keen on making sure of stability.

Edited by StephenTodd (Tue 12-Feb-13 09:48:17)

In reply to a post by StephenTodd:

The speed you see is effectively the lower of the sync speed and IP/BRAS profile. Where the new sync speed is faster than the old, you will be left with a lower IP profile which will artificially keep your speed down.

Not on a fibre connection- the IP profile is a fixed percentage of the sync speed (I forget the value- 96 point odd?) and takes effect immediately.

FTTC uses OpenReach's DLM, not BT Wholesale's, and it's a lot more end-user friendly.

FTTC uses OpenReach's DLM, not BT Wholesale's, and it's a lot more end-user friendly.

I agree that the FTTC DLM is less bad than the old ADSL DLM was.

and takes effect immediately.

Not true. As I said above, it takes effect immediately on pppoe connection. However, the pppoe reconnection does not necessarily happen immediately. Where it does not happen immediately, it could easily be deferred for weeks or even months.

In reply to a post by StephenTodd:

Not true. As I said above, it takes effect immediately on pppoe connection. However, the pppoe reconnection does not necessarily happen immediately. Where it does not happen immediately, it could easily be deferred for weeks or even months.

You may be right, but as I've never had a re-sync without a corresponding loss of PPPoE I can't comment.

I've never had a re-sync without a corresponding loss of PPPoE

I have had a few.

When there is a significant issue causing immediate loss of sync (and often an immediate degradation of DLM profile), the pppeo connection may well be in active use, and also the overall incident usually takes long enough that pppoe connection drops. However, where DLM permits a scheduled sync speed increase (2:00 am for me) after a period of stability, my experience (maybe only 4 or 5 times, so not very extensive) is that pppoe connection is not usually dropped.

As I said above, reconnecting the router can never do any harm. If you do not have an unlocked modem, there is no way to tell whether you are in the situation of an IP profile that does not match the sync speed (subject to the 96% or whatever it is ratio). That is why I suggest regular router reconnection if expecting a sync increase.

he is correct. the ip profile is set on the pppoe connection success.

I must admit I didn't realise that an IP profile update only happened at PPPoE time and not on a re-sync.

In my defence, as I've never had the the second with the first there's no way I'd have found out

I agree, it doesn't do any harm to reboot the router now and then- if nothing else it gives the system tables etc a good clear-out

In reply to a post by billford:

I must admit I didn't realise that an IP profile update only happened at PPPoE time and not on a re-sync.

This has been the norm for me, I don't think my profile has ever updated automatically following a re-sync, I've had to force a reconnect to get it to change.

In reply to a post by billford:

FTTC uses OpenReach's DLM, not BT Wholesale's, and it's a lot more end-user friendly.

The IP Profile is actually set by the WBC DLM, Bill. The rest of it, noise margins and so on, are down to the Openreach one, though I'm not sure WBC DLM doesn't occasionally stick its oar in regarding the stability option.

The Openreach DLM sends out a notification on establishment of a PPP session, not on synchronisation. WBC picks that up and adjusts the IP Profile immediately. 96.79%.

As has been sort of described, the failure to adjust it happens when the modem re-sync's and re-establishes the connection before the CP drops the session. (This also happens occasionally on ADSLx - IPs seeing a constantly connected line where the modem/router log shows re-sync's).

I'm fairly sure this is what has been causing the OP so much confusion. He says the modem connection has been rock solid, but I have grave doubts about that. Then when he does anything with the router he gets the correct IP Profile.

Edited by RobertoS (Tue 12-Feb-13 13:24:26)

some of us have configured high ppp timeouts so if a unplanned resync occurs on a isp with dynamic ip then the ip is maintained.

The sideeffect is tho the ip profile isnt updated,

In reply to a post by RobertoS:

The IP Profile is actually set by the WBC DLM, Bill. The rest of it, noise margins and so on, are down to the Openreach one, though I'm not sure WBC DLM doesn't occasionally stick its oar in regarding the stability option.

Ah right... I can see where my misunderstanding was coming from.

Strictly¹ speaking, the IP profile isn't part of the line management, although it responds to it. It's really connection management, like the 40 or 80 Mbps options. I'd been assuming they were all lumped in together.



¹ Pedantically, if you prefer

Strictly speaking, the IP profile isn't part of the line management, although it responds to it.

Absolutely. It causes quite a lot of confusion. Almost always when people say they have a stuck profile, it is DLM doing its job (maybe slightly overzealously).

There do seem to be fairly rare cases (which I don't understand) where the IP/BRAS profile really does get stuck even when the sync speed has gone up and the pppoe is reestablished.

so many peeps on the the btcare site thinking the ip profile is DLM line capping.

That's probably because when DLM intervenes it will set a capped profile with a maximum rate and a minimum rate, where the minimum rate is set at approximately half of the maximum rate.

In reply to a post by billford:

In reply to a post by StephenTodd:

Not true. As I said above, it takes effect immediately on pppoe connection. However, the pppoe reconnection does not necessarily happen immediately. Where it does not happen immediately, it could easily be deferred for weeks or even months.

You may be right, but as I've never had a re-sync without a corresponding loss of PPPoE I can't comment.

It's possible that's what happens to my connection then. I can eventually fix my connection just by rebooting the router. The only problem with that theory is that it's hard to understand what event happened on the 19th of June, August, October and November that could cause REIN. Also the connection speed and profile don't seem to have changed.

But with the 19th of February coming up I've now got intensive monitoring in place. It only monitors the modem once a minute so it might miss a short resync event but I assume such an event would at least leave its mark in the form of a speed change.

Edited by Andrue (Tue 12-Feb-13 15:22:44)

If you are using BaldEagle's monitoring it shows time connected as one of the monitored fields. See C:\HG612_Modem_stats\Ongoing_Stats\Ongoing_Stats_<time>\DSL_UP_TIME.png
I agree the speed change would be almost certain to show up as well.

Sounds very curious. Do you mean December when you say November (so it's every 2 months?)

In reply to a post by StephenTodd:

Sounds very curious. Do you mean December when you say November (so it's every 2 months?)

Oops, yes. Was running at half speed over Christmas. It's typically a 50% speed drop (from a steady 70Mb/s to a variable 30 to 40). Starts on the 19th and is finally cured by a router power cycle on the 24th or later.

Well I certainly generated a discussion, but am I the wiser?!

My profile changed after I disconnected the router via the web interface (I did not wait a minute because I did not realise and reconnected straight away).

So, could one of the above please say in one sentence what I should do. (Use disconnect & reboot the router once a day, or wait for the PPPoE?)

Just wait a month or two.

In reply to a post by BatBoy:

Just wait a month or two.

Not a helpful reply.

I'd recommend that you try harder...

I beg your pardon? The poster requested a single sentence in reply.

Actually I think it is, the op's speed is still pretty good, it's far too easy to get hung up on why we are losing a few meg, when in reality for most of us it doesn't make any real difference.

So as long as it doesn't keep dropping I wouldn't worry about it, I've taken my own advice and stopped worrying about mine.

So, could one of the above please say in one sentence what I should do. (Use disconnect & reboot the router once a day, or wait for the PPPoE?)

Use disconnect & reconnect the router once a day.

Second sentence, sorry: There is no need to wait between disconnect and reconnect; there is evidence that where the MODEM is disconnected/reconnected it is best to wait between the two.

"Use disconnect & reconnect the router once a day."

So using the above will not affect DLM?

Which DLM, and affect what setting within it?

I'm beginning to wonder if you will accept any answer that isn't the one already in your head

DLM is only concerned with the Line and the VDSL connection over it, it has no knowledge of the PPP or whatever else may be happening at a higher level. It works on low level errors, stability and sync speeds.

So if you disconnect the router, which is only concerned with higher level stuff, and leave the modem alone, there is nothing for DLM to see or react to.

The upstream signalling of the sync speed to the BRAS and ISP is a good practice thing for traffic management and pipe dimension, it's not to do with the line. See the standards for BRAS functionality if interested.

Umm Phil - I think part of his confusion may be that he hasn't understood that there are two DLMs in play here. You only describe what the Openreach one does. So that could add to his confusion.

Edited by RobertoS (Wed 13-Feb-13 12:13:45)

Okay. Well part of my confusion is 34 replies to my original question, which I thought was straight forward! (Plus another 27 replies on my cross thread at http://forums.thinkbroadband.com/plusnet/f/4209010-p...

I won't comment any further - thanks for the explanations.

In reply to a post by shalom2005:

Okay. Well part of my confusion is 34 replies to my original question, which I thought was straight forward!

LOL

Does a re-synch always result in a lower IP Profile?

No.

is the ip profile system a DLM?

It has no intelligence, algorithms etc. It just is a throughput limit that is set when ppp is established based on the sync speed of the line.

there's only one line, so how are there two DLMs ?

The IP Profile is actually set by the WBC DLM, Bill.

That's a BRAS function, shirley ? as per TR59. I'm not sure calling it "DLM" is helpful.

The Openreach DLM sends out a notification on establishment of a PPP session, not on synchronisation.

The DSLAM inserts line rate data into the PPPoE or DHCP negotiations, for the BRAS or CP to use for downstream traffic shaping, agreed.

Openreach DLM responds to errors and retrains so will be using a different mechanism to keep informed, direct comms with the DSLAM I guess.

In reply to a post by yarwell:

The IP Profile is actually set by the WBC DLM, Bill.

That's a BRAS function, shirley ? as per TR59. I'm not sure calling it "DLM" is helpful.

That's the DLM for ADSL though.

Thank you BatBoy .

Clarity is very important here, as confusion abounds. For instance, you know when the Openreach DLM sets a maximum rate for the line, is that the actual sync speed or is it 98% of the sync speed

Where does that 98% come from? I don't remember seeing it anywhere.

Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly manages lines to maintain a target link quality (speed and stability). It does this for as long as the product exists.
At provision, the line is put on �wide open� VDSL2 line profiles allowing the upstream and downstream line speeds to run at the upper limit of the product option selected.

If DLM intervenes it will set a profile with a maximum rate and a minimum rate, where the minimum rate is set at approximately half of the maximum rate.

I've no idea what the bands applied might be, but I assume the sync resulting would be the upper limit of it.

That's the DLM for ADSL though.

What is ? RAMBO or whatever did DLM, IP Profiles live in a large number of boxes in Derbyshire or somewhere.

http://www.kitz.co.uk/adsl/maxdsl2.htm has a diagram - is it wrong ?

Openreach docs all work in line rates, profiles are an upstream responsibility.

http://www.sinet.bt.com/498v4p3.pdf section 1.2.1 is helpful.

Line rates are "the rate at which Ethernet traffic can be transmitted on the link"

"As a result of these overheads, the actual achievable throughput in bits per second is
dependent on the reported VDSL2 rate and frame size of the data being transmitted."

"For example, if the reported downstream VDSL2 data rate is 40,000kbit/s and the IP
packet size is 1500 bytes(i.e. Ethernet frame size at End User LAN is 1514 bytes) the
maximum throughput achievable is actually 39,178kbit/s (when measured at the EU
LAN i.e. no VLAN header, but including Ethernet header)."

In reply to a post by yarwell:

That's the DLM for ADSL though.

What is ? RAMBO or whatever did DLM, IP Profiles live in a large number of boxes in Derbyshire or somewhere.

http://www.kitz.co.uk/adsl/maxdsl2.htm has a diagram - is it wrong ?

Thanks very much for that link Phil . I note the following within it. (My bold/underline)

For more information on how Max DSL works and how its different from traditional adsl - see How DSL Max works and What is MaxDSL? . In particular look at the DLM process to see how it is responsible for the bRAS and IP profile.

Are you trying to help the OP Phil, or just trying to show off your (sometimes incorrect or incomplete) knowledge?

I particularly object to your frequent links to and quotes of BT SINs in your replies to me. I am fully aware of these, as you must realise from the content of my posts, so please desist.

Edited by RobertoS (Wed 13-Feb-13 17:38:49)

words, and for some reason I can't find them on the page linked ?

It's clear from the diagram that the BRAS is not the DLM system, but merely a consequence of the sync speed which itself is a consequence of the DLM system. Note the one way arrow. BRAS profile is a dependency of DLM via the sync speed.

I've no idea why anyone would want to conflate the line management and IP profiling into one thing when they are a) different functionalities and b) different systems

The description under "Dynamic Line Management (DLM) - Ongoing Process" on http://www.kitz.co.uk/adsl/maxdsl2.htm looks solid to me.

well you said "Where does that 98% come from? I don't remember seeing it anywhere." and I provided some information from a SIN which would go some way towards explaining that, for the benefit of anyone reading. Even you, if you wanted to.

Do you have a problem with that ?

In reply to a post by yarwell:

Openreach docs all work in line rates, profiles are an upstream responsibility.

So you're unaware that the Openreach DLM sets a profile?

I am aware that the Openreach DLM has a sync speed profile for the line which reflects the product chosen and the DLM can adjust it by applying a band which from memory has a minimum 50% of the max to avoid syncing at silly low speeds.

That's a line speed thing. It isn't an IP Profile. The IP profile is downstream shaping set by the CP in response to the speed updates that are inserted by Openreach into the PPP / DHCP negotiations.

In reply to a post by yarwell:

words, and for some reason I can't find them on the page linked ?.

Sorry . I scrolled down that page to here:-

Data Rate (bRAS profile)

The Data Rate is the fastest speed (throughput) that you will be able to download at and is profiled by BT at the bRAS.
A maximum throughput level is needed to stop more data than your line can physically achieve being sent down the backhaul and being dropped at the DSLAM.

For more information see bRAS / IP profile page.

I followed that link and my quote is from way down that page.

In reply to a post by yarwell:

I am aware that the Openreach DLM has a sync speed profile for the line which reflects the product chosen and the DLM can adjust it by applying a band which from memory has a minimum 50% of the max to avoid syncing at silly low speeds.

That's a line speed thing. It isn't an IP Profile.

So the Openreach profile is a line speed profile not an IP profile? is this line speed profile the sync speed or 98% of the sync speed?

In reply to a post by yarwell:

... in response to the speed updates that are inserted by Openreach into the PPP / DHCP negotiations.

seems slightly at variance with

In reply to a post by yarwell:

DLM is only concerned with the Line and the VDSL connection over it, it has no knowledge of the PPP

I know what you meant to say, but will the OP? Your cleverness can be very confusing.

In reply to a post by yarwell:

It's clear from the diagram that the BRAS is not the DLM system, but merely a consequence of the sync speed which itself is a consequence of the DLM system. Note the one way arrow. BRAS profile is a dependency of DLM via the sync speed.

1) The IP Profile is merely one parameter within the BRAS profile.

2) This thread is about FTTC connections. It is clear that diagram is discussing ADSL Max, with possible adaptations for WBC in the accompanying text. The DLM described there has nothing(directly) to do with the determination of sync speed on FTTC.

3) Given that the Kitz articles are describing BT Wholesale line control systems, they seem to be quite clear that the setting of the IP Profile at the BRAS is controlled by the BTW DLM.

I've no idea why anyone would want to conflate the line management and IP profiling into one thing when they are a) different functionalities and b) different systems

I have no idea why you should try to show that only one DLM is active when the evidence you yourself provide points to there being two, as originally stated.

So the Openreach profile is a line speed profile not an IP profile?

Absolutely. That's the only reference to profile in Openreach's domain that I can see. It's Generic Ethernet Access after all.

is this line speed profile the sync speed or 98% of the sync speed?

Openreach generally work in data rates, as per the SIN excerpt I posted earlier. So I expect it is set as a data rate but I don't know if the DSLAM is given a sync speed to work to or a data rate - do you ? The outcome would be the same.

In reply to a post by RobertoS:

Where does that 98% come from? I don't remember seeing it anywhere.

I meant 96.79% I think. Did I mention I was confused?

I wonder where the calculation of "IP profile = Sync speed * 96.79%" is done?

In reply to a post by yarwell:

Openreach generally work in data rates, as per the SIN excerpt I posted earlier. So I expect it is set as a data rate but I don't know if the DSLAM is given a sync speed to work to or a data rate - do you ? The outcome would be the same.

No I don't, but I suspect it's sync speed.

Maybe one way to find out would be to determine if the "IP profile" or equivalent for Sky matches the sync speed of an unlocked modem or is 96.79% of the sync?

Edited by deleted (Wed 13-Feb-13 18:48:58)

I wonder where the calculation of "IP profile = Sync speed * 96.79%" is done?

by the CP / BT Wholesale I think, so that it reflects the amount of user data that can pass downstream at the frame size they use. BRAS units have that task.

"For example, if the reported downstream VDSL2 data rate is 40,000kbit/s and the IP
packet size is 1500 bytes(i.e. Ethernet frame size at End User LAN is 1514 bytes) the
maximum throughput achievable is actually 39,178kbit/s (when measured at the EU
LAN i.e. no VLAN header, but including Ethernet header). Alternatively, if the IP
packet size is 64 bytes the maximum throughput achievable is further reduced to
35,721kbit/s. This overhead is particularly important to consider in respect to the
downstream shaper setting on the CP�s BRAS. CPs are advised to understand and
account for the method that theirBRAS uses to implement traffic shaping."

So, it looks to me like the Openreach DLM sets the sync speed, and the BTW Bras sets the IP profile.

In reply to a post by BatBoy:

So, it looks to me like the Openreach DLM sets the sync speed, and the BTW Bras sets the IP profile.

Yes indeed. Openreach set the DSLAM up to send sync speed / data rate information upstream at connection time, but it's BTw or other CPs that have to decide what if anything to do with it. Openreach advise that traffic shaping is used to limit the downstream data to what the line can handle.

where is the variance ?

The DLM is only concerned with the line speed. It has no knowledge of PPP. I'm happy with that. DLM works on errors, resyncs and the like - data from the DSLAM.

The IA in the DSLAM inserts the speed into the PPP or DHCP session negotiation. The CP can use that to define downstream data rate profiles.

Please explain.

I see, a different page I hadn't read. Thanks.

Perhaps the conflict between http://www.robertos.me.uk/html/bt_wholesale_dlm.html and the Kitz diagram should be resolved one way or the other. Your page says "The two main things it sets are the �target� noise margin and the IP Profile. Please see the links in the menu on the left for details." whereas the Kitz diagram shows the output of DLM going to one or more other systems before arriving at the BRAS where the IP Profile is actually set.

Edited by yarwell (Wed 13-Feb-13 21:04:25)

1. Please list the others.

2. Indeed, Batboy (or someone) raised the ADSL issue presumably to identify "BTw DLM". I agree it is irrelevant to FTTC sync speed, but relevant to IP profiles which is exactly what this thread is about.

3. The setting of the IP profile at the BRAS is not controlled by the BTw DLM. It uses data (the sync speed) from the DSLAM which results from the actions of the DLM.

Where exactly is this second DLM ? For clarity, by DLM I mean something that acts upon the line speed from the CPE to the DSLAM.

I think (hope) we're all clear that DLM relates to LINES and IP Profiles relates to downstream traffic shaping ?

where is the variance ?

Quite. No variance in principle. But there is variance in terminology that is causing the confusion. At least I'm sure the OP has long left the post is isn't getting more confused.

We all agree (I hope) on the basics.

1 - There is a low level DLM at the cabinet that controls the cabinet->modem connection and does almost all the interesting stuff. The immediate effect of this is most easily seen (with unlocked modem) by the sync speed.

2 - There is higher level control (IP profile) at the BRAS. This is set from the sync speed on pppoe connection. It is presumably designed to ensure that the cabinet is not given data faster than it can pass it on to the modem. It is also used to limit speeds based on the maximum the service contract is willing to provide (eg 10/40).

3 - The setting of (2) from (1) is at pppoe connection time; sometimes (but not always) forced when (1) forces a low level resync.

4 - Too much playing with the modem can affect the low level DLM.

5 - Playing with the router can force pppoe resync (which can be beneficial). It will never harm the low level DLM. It will never harm the higher level IP profile. It may lower it, but only where the sync speed is already low.

Terminology variance comes as to whether we use the term DLM for the BRAS system. It clearly is DLM: it's digital and it manages the line (or that depends what you call the line). Nevertheless, I would personally avoid the term DLM for this and reserve it for the low level cab->modem DLM. I don't know if this is common practice. The confusion is made worse as in the ADSL world the two were inextricably intertwined.

~~~

Unknown (to me) is whether the BRAS/IP profile ever gets 'stuck' for reasons that are caused neither by the sync speed nor by the contract terms. I'd still appreciate it if anyone could give more clarity on that. There clearly are cases where people have an IP profile much faster than the speeds they actually see; even after a router reset should have made the IP profile match the sync speed. In some cases these low speeds don't seem to be fully explained by congestion, local wireless setup, etc.

Edited by StephenTodd (Wed 13-Feb-13 21:06:12)

Dynamic Line Management is usually used to describe the parameters that affect the sync from the DSLAM to the CPE. Googling for "Dynamic Line Management" generates a consensus on this.

I think is confusing and unnecessary to consider anything after the DSLAM as a "line" personally. A "line fault" ought to be something involving a bit of wire and not a setting in a database 100 miles away.

I'm not sure the DLM does live at the cabinet, when I looked in one there wasn't a box that would fit the bill unless it's a feature that the DSLAM has internally (not that its location matters much).

Any large database seems prone to errors IME, so a "missing" sync value leaving a profile sat at the wrong setting in the BRAS would not be a shock. In terms of throughput measured vs sync or profile, I'm usually drawn back to the 20M / 30M provisioned capacity and CIR on the cab - exchange fibre, is that coming into play anywhere ?

You can also get horribly low throughput despite decent sync if the error rate is high.

In reply to a post by yarwell:

Dynamic Line Management is usually used to describe the parameters that affect the sync from the DSLAM to the CPE. Googling for "Dynamic Line Management" generates a consensus on this.

The Huawei SmartAX MA5616 MSAN has several dozen(?) different 'port' parameters which affect the sync from DSLAM to CPE.

Just to put the cat among the pigeons, Huawei never explicitly refers to DLM, or at least I can't find a reference.

There is however reference to Dynamic Optimisation Profile/.s It seems that the MA5616 can be configured with up to 256 different optimisation profiles, and each profile can be bound independently to one or more ports of a subscriber line card.

cheers, a

I hope we may get near to a resolution of the disagreement here.

The Kitz links initiated by you re the BTW DLM for ADSLx , (as I get the impression you believe in the gospel truth of Kitz), intimate that the DLM controls the BRAS line Profile and IP Profile settings.

My view for a long time, which I have mentioned elsewhere in these forums in the past but no idea when or where, ever since I started wondering where the IP Profile for FTTC is coming from, is that there is a simple lash-up at the MSAN as it receives the GEA link data. Whereby the line sync value supplied by the OR DLM is fed onwards into the WBC DLM and thence to the BRAS, rather than the sync negotiated by its own line card for ADSLx connections.

At no point have I disputed that the BRAS is where the value is held - though posts in the past by Plusnet staff clearly point to there being more than one place. (Quite apart from the Plusnet copy).

My statement that two DLMs are involved is therefore valid. The OR one controls the line sync. The WBC one controls the throughput using the IP Profile. Both DLMs are involved.

If you wish to argue that the WBC DLM does not control the throughput on either ADSLx or FTTC, then sorry - I'm trying to explain the system in useful terms to people who want something they can understand. You seem to want all explanations to be at the PhD thesis level.

In reply to a post by asbokid:

The Huawei SmartAX MA5616 MSAN has several dozen(?) different 'port' parameters which affect the sync from DSLAM to CPE.

Just to put the cat among the pigeons, Huawei never explicitly refers to DLM, or at least I can't find a reference.

There is however reference to Dynamic Optimisation Profile/.s It seems that the MA5616 can be configured with up to 256 different optimisation profiles, and each profile can be bound independently to one or more ports of a subscriber line card.

Ah, the words of someone who has practical knowledge of the Huawei MSAN's innards!

(And I resent being put amongst a clutch of cowardly flying 'tree rats'. )

Edited by burakkucat (Thu 14-Feb-13 04:31:53)

I have seen reports from users where they have been told their line has a min and max data rate set at the DSLAM by the DLM. In some cases in bad line faults users have been unable to get a sync because the line cannot meet the min rate set by DLM. The min rate seems to be set to half the rate of the max rate whenever its been made known but I am not sure how lines start out, eg. if the 80/20 product had a default of min 40 max 80 then lines that are not good enough to sync at 40 wouldnt work, so I was curious if default profiles are based on estimates but I am not convinced by that either as sometimes starting syncs can vary widly from estimates. So I think the default min and max may well be min 15 max 80. Which only gets changed after DLM detects problems.

If the minimum was 15, which I think is unlikely, then lines that could not reach 15 would not work.
I suspect the minimum starts out as zero.

I have seen reports from users where that has happened, line doesnt sync, openreach installer either aborts or offers to proceed but user accepts the lower speed, and then the profile gets changed to allow it to work. Plus the 15mbit reference in the openreach docs exists.

In reply to a post by Chrysalis:

I have seen reports from users where that has happened, line doesnt sync, openreach installer either aborts or offers to proceed but user accepts the lower speed, and then the profile gets changed to allow it to work.

Where?

I think was on btcare forums but cant find it now, but could have been one of many places as I found a fair few discussion sites.

That sounds more like the ordered product is changed. Infinity has a minimum speed of 15Mbps sync - but that is a BT Retail specification, nothing to do with the underlying GEA product. So nothing to do with what other ISPs do/accept.

Below 15Mbps on BT Retail the customer has to have the "Faster Broadband with Fibre" or whatever its current name is.

ok after checking docs it seems openreach have a minimum of 2mbit sync speed required.

the 15mbit is the prioritisation rate.

so I guess logically the default is set to min 2 and max 80.

Edited by Chrysalis (Thu 14-Feb-13 21:17:55)