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Standard User R0NSKI
(fountain of knowledge) Mon 21-Apr-14 18:15:21
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Is fast path possible on all three profiles/modes?


[link to this post]
 
This news article states there are three modes the DLM can be set to.

Standard best overall balance between speed and stability for general internet users.
Stable prioritise stability over speed for IPTV video conferencing, home workers and businesses transferring data and IPTV.
Speed prioritise speed over stability for online gamers.

Would I be correct in the assumption that all three modes can be on fast path if the connection was good enough, and that the DLM would use differing trigger levels of errors for applying/increasing interleaving?

So the speed profile will require the most errors before the DLM intervened and with the stable profile the DLM would intervene earlier, the other would be in between.

Standard User RobertoS
(sensei) Mon 21-Apr-14 21:06:34
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Re: Is fast path possible on all three profiles/modes?


[re: R0NSKI] [link to this post]
 
Hmmm tongue. Contrary to what I said a bit ago in another thread you are in, Andrew mentions an Openreach "speed" profile there. Grrr!

Note, as long as Andrew has his grammar correct, (which is never a given), the following says Fast path is available on all three.
In all three modes the system will tune the connection, setting fast or interleaved mode for error correction and once in interleave mode vary the depth of interleaving, the deeper the interleave the more tolerant the line is to errors at the expense of increasing latency and some throughput speed.


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Standard User R0NSKI
(fountain of knowledge) Mon 21-Apr-14 22:13:55
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Re: Is fast path possible on all three profiles/modes?


[re: RobertoS] [link to this post]
 
Which is what I believe to be the case, but someone else in that thread was adamant otherwise. They believe you can only have fast path on the speed profile, implying the other two will always be interleaved regardless of error rates.


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Standard User WWWombat
(fountain of knowledge) Tue 22-Apr-14 03:05:35
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Re: Is fast path possible on all three profiles/modes?


[re: R0NSKI] [link to this post]
 
In reply to a post by R0NSKI:
Would I be correct in the assumption that all three modes can be on fast path if the connection was good enough, and that the DLM would use differing trigger levels of errors for applying/increasing interleaving?

So the speed profile will require the most errors before the DLM intervened and with the stable profile the DLM would intervene earlier, the other would be in between.


Exactly right. The different profiles offer different thresholds before DLM intervenes, though it monitors for resyncs as well as for errors. If your line is so perfect that it never resyncs, and never has any errors, then it can be considered stable.

My old ADSL1 line used to get less than 10 CRC errors per hour. Why would you need to take fastpath off that just to give it a label of "stable"?

I wonder what G.INP will bring, when BT get a different tool to use instead of FEC/interleaving (or to use before they revert to FEC/interleaving). My little reading on that subject suggests that FEC and re-transmission are used instead.
Standard User R0NSKI
(fountain of knowledge) Tue 22-Apr-14 06:13:01
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Re: Is fast path possible on all three profiles/modes?


[re: WWWombat] [link to this post]
 
Thanks WWWombat.

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