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What Is DLM? Everything you need to know

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What Is DLM? Everything you need to know about DLM and how it affects you.

DLM - Dynamic Line Management.

Dynamic Line Management (or DLM) is the collective term for the automated system that logs information about your line's performance, and processes that are used to stabilise the line. DLM uses the information it gathers about disconnections and reconnections as well as error statistics to establish what speeds are likely to be most stable for your particular line. It may also determine that interleaving should be activated on your line if not already present. It should be noted that frequently restarting your router or modem may be interpreted by the DLM as a problem and may subsequently reduce the controlled line rate.

If DLM can see that a connection can support an increase in speed it may increase your speed upwards. If a connection becomes unstable then DLM will reduce the speed and attempt to re-stabalise the connection by adjusting the line's parameters, of which there are several, speed will be one of them.


Why is this DLM happening?

DLM is being used to stabilise the line quality between the router and the DSLAM in the BT exchange. The reasons for this can be many, but it is often to condition lines to be able to support data that is not tolerant of line errors and router re-syncs. Examples would include VOIP and Streaming Video, there are others too. Generally, web browsing, email, file transfer and general downloads are not noticeably affected by line errors (that are corrected by the line protocols) and so may have existed unnoticed previously.


But I don't want those other services, I am happy with what I have now.

An ISP will generally perform this kind of work on it's entire network. There is no current means of pre-registration to be excluded from DLM. It may, however, be possible for you to have your previous settings restored after DLM (see below).


How Do I know If DLM Is Running On My Line?

The tell tell signs of DLM is the 412/794* upload stream rates, your speed may vary throughout the day.


How Long Does the DLM process last?

The DLM process can take up to 20 days or even longer in extreme circumstances. But its usually 10 days min.


Great I'm On DLM , Should I Leave My Router On?

This is probably one of the most important things you as a customer can do. To ensure the DLM process is uninterrupted you must leave your Sky Wireless Router on at all times during the DLM process!

If you disconnect, power cycle or reboot your router the DLM process may class these actions as a disconnection and could the reduce the line speed even more.


What Type Of Speed Can I Expect?

You should expect anything within 1MEG of what your line was achieving before the DLM.


Is there anything else I can do?

Yes, you should (as soon as you can now you've read this) check that you do not have any internal extension wiring problems. There are guides on this forum to help check and resolve wiring problems which may be interpreted by DLM as a poor quality line and subject you to a lower speed than your line should be capable of supporting. Visit our Cabling and Faceplate forum here.


What shouldn't I do?

Apart from not messing around with your router during DLM you really should not bother calling into Sky CST and asking to have your speed reset to its former value. Even if you persuade the CST to do this, while DLM is running it will automatically be set to whatever DLM decides it should be.


DLM has finished on my line, but the speed it very slow. Can I do anything about it?

Yes. Once DLM is complete on your line you should make a call in to Sky and ask for your line to be manually set to a higher speed. Sky's current policy is to set the line to within 1Mbps of what it was prior to DLM (NB: This may change). Or you can use this online form.


Will I be put under DLM again?

It is quite possible that DLM will be run on your line again in the future. It is a permanent feature of the network and will identify and work on any lines that drift out of tolerance. This can, in some cases, work in your favour if your physical line quality improves - for example, after you repair any internal wiring faults.


Discuss this in our forums.


With thanks to Monday for the original suggestion, and those that have submitted info to myself via PM.

Comments (1 posted):

AspieMum on 10 May, 2012 23:03:57
avatar
You may have no choice but turn off the router even in DLM. If you lose your broadband connection you can have to unplug it for a short period then plug it back in & restart the router just to get any internet access.

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