IP profile why?

Is there any benefit for the end user to have an artificial cap on the available speed of their broadband product. As i'm scratching my head..

My profile has dropped from 77.4 to 62.2 after I had turned off my modem.

I was told by the Openreach Engineer a solid 80/20 sync which I was very happy with as my estimate was 51.
Having said that i'm only 350mts from the Cab, all underground 10 year old copper so the line should be good.

I've been told on the BT forum that because my profile is above the estimate, it is not a fault and they can't get an engineer out.. Why does it take an engineer visit to basically come to my house test the line to say its fine and then to call somebody back at the office to reset the DLM. Its crazy..

So, for now I'm going to monitor it over the next 4 weeks to see if the DLM actually goes back up.
And i'm due to receive an Unlocked Modem to view my Max Achievable and Syncs. (If this is around 60 then i will eat humble pie ..)

In reply to a post by dazzlew:

Is there any benefit for the end user to have an artificial cap on the available speed of their broadband product. As i'm scratching my head..

Sorta. The benefit really is to avoid having more data sent toward your modem than the line can carry. That would cause data to be rejected and packets dropped. Think of it like filling your car fuel tank - you don't want fuel coming out so fast that some sloshes back out the filler and onto the forecourt. By avoiding such 'wastage' BT reduces its costs and improves the efficiency of its network. So we probably benefit because it reduces BT's running costs which in turn probably reduces the amount it charges.

I admit though that it's difficult to understand why BT need to do it. LLUOs don't normally have profiles so presumably they don't care about excessive data flow or else use handshaking to avoid it.

Edited by Andrue (Tue 19-Feb-13 20:22:59)

A few on here think the FTTC DLM is better than the ADSL system. It may well be.

But I think the FTTC DLM is more than just interleaving and banding, I think there is also power output control, possibly not even just to manage one line but is possible DLM is also monitoring multiple lines on a line card. All speculation on my part of course, but most mentioned on here is speculation anyway.

In terms of LLU, its my view the amount of complaints from people without DLM is lower than with DLM.

In regards to the IP profile remember thats not whats controlling the line speed, its just a throttle placed to limit the throughput, assuming its not stuck at a wrong level then it will be set slightly below the sync speed anyway. It was on adsl where the IP profile was a big problem. I agree I am not convinced its needed, there isnt many real world situations where a line would have out of control too much data going down it, the only situation I can think of is a denial of service attack. But here in this topic the IP profile isnt the problem, but of course since he cannot see his sync stats we can only guess why the speed is down.

Thanks for the detailed opinions.
I will post back hopefully tomorrow once I've fitted the HG612 and Telent my stats..

the only situation I can think of is a denial of service attack

Have a read at the spec for a BRAS. Managing the internet connection capacity while allowing for multicast TV over the same connection is another use case, as are other multi-service down the same line. But the real need is in managing multiple services from multiple providers over one network efficiently, upstream of the line.

Vectoring effectively does multi-line DLM, no evidence to suggest it exists otherwise.