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FalconEvo
Beginner
8,522 Views
Message 1 of 12

High Interleave Depth on Downstream - Previously on FastPath (1)

Hi,

 

I have been having some latency issues with my VDSL line since I was required to re-locate the HG612 modem a couple of times due to some decorating that was going on.  After leaving the line in sync for over 14 days after the work was complete, DLM did not return my line to normal.  I performed a reset of the modem yesterday evening in an attempt to remove the high downstream interleave depth.  I don't believe there to be any issue on the line, just simply that I had to power on/off the modem a couple of times.

Unfortunately since then, the modem has re-sync'd with a very high interleave depth (856) on the downstream.  The upstream remains on fastpath interleave depth 1.

Can the Mod team perform a line profile reset on my VDSL line please as I used to have a latency that was sub 8ms, now its up near 30ms.   I host some NS2 dedicated servers which are heavily dependant on low MS to the target client so a reset would be appreciated.

 

I can perform the bt speedtest if required, however as I run a dual-wan setup combined with VirginMedia 120Mb you will get an errornous result as the downstream & upstream testing as my line is 180Mbit/22Mbit in dual-wan lb mode.

 

I would appreciate it if the Mod team can perform this for me, just to return the line back to fastpath 1 on the downstream. I believe any FTTC/FTTH provider should be able to manage the DLM functionality of the VDSL with the provided details from OpenReach, as letting DLM use its automated functionality is fine but it is far from a polished and finished system.  DLM has its own problems in both ADSL and VDSL technology, as such it would be wise for BT to request the DLM disable functionality from OpenReach as a large portion of users (people who do gaming or use VOIP) would prefer a full fastpath line regardless of the minor amount of errors.

Cheers,
FalconEvo

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11 REPLIES 11
Guru
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Message 2 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

You need to ask the mods explicitly at: http://bt.custhelp.com/app/contact_email/c/4951.  But be aware they take 3 working days to reply: sometimes more if busy.

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Distinguished Expert
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Message 3 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

i read somewhere that an error rate of more than 1 fault per every minute will cause dlm to increase snr and-or interleaving and an error rate of less than 1 fault per every 10 minutes will cause dlm to decrease snr and-or interleaving
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FalconEvo
Beginner
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Message 4 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

Many Thanks for the Link. I have filled in the details and hope to get a response.
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FalconEvo
Beginner
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Message 5 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

Sounds a little like hear-say to be honest, I doubt BT OR will release the details of the DLM platform as when I worked for Opal Telecom we never released any details of the TT DLM (which was unreliable at the best of times)

I would imagine only a select set of BT OR network/software engineers actually know the exact functions of the DLM system.
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Distinguished Expert
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Message 6 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

results such as those are easily obtainable by testing and observation
why do you think your ip profile has been changed?
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FalconEvo
Beginner
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Message 7 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

The interleave delay has gone from 1 (which is fastpath) which was also giving 6-8ms to the bt gateway, since the modem restart and relocation (due to decorating the modem was simply put on a shelf, no cabling changes aside from a longer power extension)

 

Now the interleave delay is 856 on the xdslcmd statistics, which means I now have a 25-30ms round trip to the bt gateway.  The gateway IP has stayed the same, simply the interleaving has been enabled on the downstream of the line.  The interleave delay and the routing that BT use increases the delay on the ping time by approximately 25ms, quite a considerable amount when its un-neccesary.

I worked for 8 years from dsl 3rd line to NOC, from pipex > tiscali > talktalk > opal telecom.  I know what im talking about, Im simply asking for a line reset to clear the current DLM settings.  This should allow the line to resync with no interleave delay on the downstream.

 

As I have already been patient enough to await DLM to clear the problem itself (waiting over 14 days with a rock solid sync, snr, up&down db) it has not made the slightest bit of difference.  So either DLM not responding as it should be or it is claiming there is a line fault, considering the errors on the line are near none-existant after retrain its unlikely.

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Distinguished Expert
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Message 8 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

dlm responds to the error counts on the line over a 24 hour period and also the number of retrains
if you counted these you may be able to look back and see why your profile has been lowered
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Guru
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Message 9 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)

I would imagine only a select set of BT OR network/software engineers actually know the exact functions of the DLM system.  Probably a select set of zero?

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FalconEvo
Beginner
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Message 10 of 12

Re: High Interleave Depth on Downstream - Previously on FastPath (1)


@Bullitt wrote:
dlm responds to the error counts on the line over a 24 hour period and also the number of retrains
if you counted these you may be able to look back and see why your profile has been lowered

As I have mentioned, the line has very little errors and had no retrain in over 14days.   Stil, the interleave on the downstream is present as DLM is either frozen or not reading the line correctly. 

 

Prior to this the modem was disconnected twice, once to place it on a longer extension to be relocated up on the shelf, the other to return it back to its original home without the power extention.

 

Im aware of exactly what DLM does, however in this instance it is not functioning correctly.  If it requires manual intervention to nudge it back in to fastpath, thats all I require.

Not allowing the manual setting of FastPath with DLM auto functionality disabled is a serious oversight from the engineers involved in the provisioning of the product.  DLM should always be present for the 'average' user to see lolcats online with a stable connection, plus most users are only interested in throughput over latency.  However in certain circumstanes DLM should be manually specified to the needs of the end user/customer.

 

If there was enough demand from the customer base, it would get done.  However most people just assume the latency they have on Infinity is 'how it is'.   There are quite a number of threads asking for FastPath to be introduced on the product but without the community/customers forcing the issue, nothing will be done.

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