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Author Topic: FTTC - DLM 10 day training period  (Read 4673 times)


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FTTC - DLM 10 day training period
« on: January 11, 2012, 08:39:10 AM »

There appears to be a general school of thought that the traditional DLM 10 day training period that applies to ADSL services is still applicable to FTTC "up to 40Mb" services.

Indeed, some ISP Customer Service agents still refer to the 10 day training period.

However, an extract from BT's SIN 498 document (  ) states the following:-

2.2.5 Dynamic Line Management

Dynamic Line Management (DLM) is employed in GEA-FTTC. DLM constantly
manages lines to maintain a target stability. It does this for as long as the product

At provision, the line is put on wide open profiles, allowing downstream line speeds
of up to 40Mbit/s, and upstream line speeds of up to 2Mbit/s or 10Mbit/s depending
on the upstream product option selected.

On the first day of operation, DLM will intervene if severe instability is detected.
Otherwise, DLM will wait until the day after provision before intervening, provided
that the line has been trained up for at least 15 minutes during the preceding day.

If 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. The
purpose of the minimum rate is to ensure that the line does not train at a rate which is
significantly below the level the line should be able to achieve. If this happened, then
the line is likely to remain at a very low rate till a re-train is forced by the user
powering off the Active NTE.

Note that the upstream throughput is also constrained on the DSLAM to the upstream
rate requested in the order, ie 2Mbit/s or 10Mbit/s, so even if the upstream line speed
is higher, the upstream throughput is constrained to the level ordered for the product.

I have not seen anything contrary to this statement, so I presume the same will apply when the "up to 80Mb" service is fully implemented.



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Re: FTTC - DLM 10 day training period
« Reply #1 on: January 11, 2012, 09:35:57 AM »

so I presume the same will apply when the "up to 80Mb" service is fully implemented.

I too, not having seen anything to the contrary, will agree with your presumption.
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

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