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Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

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Registered: 11-08-2007

Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

I understand how the Plusnet "Current Line Speed" is derived under normal circumstances, and how it is updated from the BT "IP profile".
My question is - are Plusnet's systems capable of allowing a customer's "Current Line Speed" to set to a manually chosen value AND prevent that value being changed when subsequent "IP profile" updates arrive from the customer's telephone exchange ?
I appreciate this is not how it would have been designed to work, but I think there is a good reason for having the option to do so.
There have been several forum topics recently, where customers have been complaining either about packet loss or that the Plusnet traffic prioritisation scheme is not working correctly.  These complaints are usually from gamers on congested exchanges, for whom packet loss, QoS, and latency, are all more important than available download speed.
It seems to me, that on congested exchanges during overloaded peak usage times, that the Plusnet "Current Line Speed" will be allowing data to be sent to the customer's exchange too quickly, and as a result will inevitably cause packet loss, and for the traffic prioritisation to become ineffective.
Under these abnormal circumstances, if the customer agreed to accept a slower download speed - in exchange for improved traffic quality,  then would there be any merit in having Plusnet manually override the "Current Line Speed" to a lower value (to match the reduced effective download speed at peak congestion) in order to make the traffic management work as it should - albeit at a permanently reduced download speed.
Admittedly, this reduced service would then have to be regularly reviewed, so that the download speed could be returned to normal operation after BT have removed the cause of the exchange congestion - having upgraded the Virtual Paths, etc.
If what I have suggested IS possible, then it my be the solution for many gamers on this forum reporting problems, where those problems can be shown to be due to being on a congested exchange, rather than a line fault or other equipment issue.
Huh
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Community Veteran
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

This sounds like an interesting idea.
From what I'd gleaned some time back, this can be done, but it would be a manual process, and therefore unlikely to be done, certainly on any widespread basis.
But with most congested connections I've seen, the speeds have dropped that low, I'm not sure this idea would actually yield any overall benefit.
Then of course there is the point that congested connections shouldn't be a long term thing - whilst we have seen a few that have gone on too long, that's mainly because BTw have failed to recognise the congestion and Plusnet have failed as well, or failed to press BTw on the issue.
The primary exception to the longer term problem would more likely to be with 20CN as I can't see BT wanting to upgrade capacity in a hurry on this older technology.
goldenfibre
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Yes another vote up for me as Plusnet should fix IP Profile permanently at 78Mb (for 80/40 FTTC) and 38Mb (for 40/20 FTTC) and 24Mb (for ADSL2+ 21Mb) and 8Mb (for ADSL 8Mb)
Edited: Voted NO now
Community Veteran
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Errrrm  .....  ....  ....  NOCrazy
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Definitely no
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Just wondering about this,
If a particular user on a congested exchange link has data sent a bit slower will this make any significant difference to the total load on the link?  If not then pretty much the same percentage of that user's data might still be dropped due to everyone else's traffic still clogging things up I'd have thought - still an interesting idea for discussion though.
Call me 'w23'
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goldenfibre
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Ok I going to put voted NO!
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

Quote from: purleigh
It seems to me, that on congested exchanges during overloaded peak usage times, that the Plusnet "Current Line Speed" will be allowing data to be sent to the customer's exchange too quickly, and as a result will inevitably cause packet loss, and for the traffic prioritisation to become ineffective.

The problem is those links are shared amongst other ISPs using the BTw network. For any changes to be made, everyone would have to agree and implement them.
In reality, I just don't see this as practical.
Community Veteran
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

This will make your head hurt ! -
I understand completely what you are saying, but it does depend on how the BT equipment drops packets.
If the packets were dropped in a truly random manner, then what 'w23' said would apply.
However most digital communication systems fill their data pipes in a round-robin polled manner, so that some data from each incoming feed is multiplexed along the pipe.  
This has several advantages -

  • Nobody is excluded from having some portion of their data transmitted.

  • Traffic prioritization (such as Max Premium) or other contention control methods (e.g. 20:1,  50:1,  etc) still works.

  • For a given traffic priority, every user should see a similar minimum throughput.


Under these conditions, each customer will see the same minimum level of throughput as everyone else, as it will be the packets that exceed the pipe's total capacity after round-robin pipe filling that will be randomly lost.
Therefore the effect of artificially limiting the "Current Line Speed" could work, because the lost packets will belong mostly to those feeds that are sending the data too quickly for the current conditions.
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Re: Can the Plusnet "Current Line Speed" be set permanently to a fixed rate ?

I don't think you understand the issue goldenfibre, this suggested idea would be at user request/agreement.
But that said, I think AndyH has actually made a very important point that would make the workability of this idea impractical. All users on a VP would have to be restricted for it to work and some may not wish to be, for example they may wish to schedule certain usage outside of peak time when they won't be impacted by congestion to the same extent, if at all.
I doubt whether even a modified DLM could provide a satisfactory solution, but there's an amusing thought.