Changes to DLM Incoming

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Lizard Networks

#1794174 3-Jun-2017 11:49

Gordy7:

No notification received...

Only indication was that my VDSL was not working for several minutes....

IP remained the same so I guess there was some sort of re-sync...

Oh i get what your saying now.

you mean the normal DLM modifications, this realistically won't be happening daily and the time of day is chosen for good reasons.

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Gordy7

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#1794190 3-Jun-2017 12:53

Maybe it is not a VDSL DLM timing issue...

Strange that my Skinny HG659 appears to have lost internet connection 2 days in a row at around 0530.

System logs do not show enough info. Trying to set up a remote logging server to get lengthier records.

I do see that my system has been up for 6 days, but that the VDSL up time shows about 45 minutes.

For my line I am generally getting good and consistent speed (25/4.5). I have had the modem for 3 months now.

Internal wiring is 3 metres to demarcation, no filter, no alarm and no other devices or extra wiring on the line.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

Jase2985

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#1794221 3-Jun-2017 14:27

Djmixerdomo:

Jase2985:

Djmixerdomo:

My line did a re-sync earlier in the week. SNR hasn't changed but the attainable speeds went up by ~10Mbps on both Up/Down

Real world speeds haven't changed of course because of the cap, it would be nice if those were lifted :)

its not a cap. i believe its a physical limitation on the line card.

According to this comment by @hio77 they're artificially limited:

https://www.geekzone.co.nz/forums.asp?forumid=49&topicid=210455&page_no=9#1774664

I wonder what the actual limit is?

i imagine and im only guessing here is its between 70 and 80mbps, they have used 70 as its a nice round number.

Smix

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#1794391 4-Jun-2017 01:15

Hey team,

I managed to get a small increase in performance from 17/1 to 19/1.2, however, the last few days have seen me rubber banding in online gaming (Rocket League in particular). I've tried restarting everything a couple times very early in the morning, but I can't seem to get any improvements. I haven't had an issue in the past (I've had VDSL for just under a year now) so I'm assuming that these changes are the reason for the latency? increase.

Is there anything else I can try? My setup is:

Master filter
HG640B in bridge mode
DLINK Viper

My PC is plugged in via ethernet; my house has Cat6 cabling throughout.

Linux

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#1794400 4-Jun-2017 02:07

@smix You need to look at some trace routes to the games server and compare when things are good and when they are bad I doubt it's relates to DLM

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darylblake

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#1794406 4-Jun-2017 07:29

Linux: @smix You need to look at some trace routes to the games server and compare when things are good and when they are bad I doubt it's relates to DLM

Linux

If Latency is funny you need to be measuring from the BRAS to your modem. E.g. First HOP. When you think latency is causing problems.

Smix

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#1794421 4-Jun-2017 09:06

Thanks @Linux and @darylblake for your responses!

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smalltrader

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#1794427 4-Jun-2017 09:31

Smix:

Hey team,

I managed to get a small increase in performance from 17/1 to 19/1.2, however, the last few days have seen me rubber banding in online gaming (Rocket League in particular). I've tried restarting everything a couple times very early in the morning, but I can't seem to get any improvements. I haven't had an issue in the past (I've had VDSL for just under a year now) so I'm assuming that these changes are the reason for the latency? increase.

Is there anything else I can try? My setup is:

Master filter
HG640B in bridge mode
DLINK Viper

My PC is plugged in via ethernet; my house has Cat6 cabling throughout.

Hi Smix,

I do believe your issue is ddDLM related. ddDLM has the best intention and increase your sync speed as it thought your line can sustain a higher throughout. Unfortunately that causes a number of issues for you.

1) You have quite a lot of CRC errors within a span of 24 hours

2) Your FEC errors rate is massive within 24 hours. Normally, you wouldn't worry too much about FEC errors. However, high FEC errors together with high CRC errors are not a good sign

I believe if you do a SpeedTest you will see high latency which will affect interactive apps and gaming.

I have observed how ddDLM work on my line since it went live about 6 weeks ago. Some changes are defnitely good like signifciant increase in up stream bandwith. However, the default position of ddDLM pushing everything to a higher sync as a starting point may cause issues for some people (eg. people who game online). In my case, ddDLM pushes my down stream sync from about 50 Mbps to about 62 Mpbs. This causes significant CRC errors and the latest adjustment has seen the the Down Stream sync paired back to 48 MBps with significantly lower CRC rate and lower latency.

Unfortunately, ddDLM is fully automated. You can't tell ddDLM that you are a gamer and your perfer lower latency to higher sync speed. The only thing you could do is to wait and see if ddDLM will do the right thing and pair back your sync rate to improve on CRC errors and latency. Often high sync rate with high latency/high error rate is actually not good from an overall performance's perspective.

A last resort may be to ring your ISP and ask them to lock you into a certain profile but that is probably not deisrable either long term

Jase2985

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#1794431 4-Jun-2017 09:56

@smalltrader 1163 CRC errors over 39 hours is not much at all, that equates to .5 CRC errors per minute, that is nothing in terms of VDSL. its something like more than 10 per minute before you start to worry.

you are correct about the FEC errors though, thats super high.

smalltrader

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#1794435 4-Jun-2017 10:04

Jase2985:

@smalltrader 1163 CRC errors over 39 hours is not much at all, that equates to .5 CRC errors per minute, that is nothing in terms of VDSL. its something like more than 10 per minute before you start to worry.

you are correct about the FEC errors though, thats super high.

You are right and I did not do the math correctly. I did the math over 24 hours but I guess even that the CRC is still within acceptable parameter.

I think the problem with the original poster is that his line is already on the borderline and there is no margin to play with. Any increase in latency / CRC errors just push it over the cliff especially if you are gaming. ddDLM does not know that one a gamer or not.

Jase2985

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#1794436 4-Jun-2017 10:13

i would say the FEC's are the killer at the moment

freakngeek

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#1794511 4-Jun-2017 12:00

Jase2985:

i would say the FEC's are the killer at the moment

Agreed
FEC (Forward Error Correction) = 11,519,897 (I take it individual errors not as in Draytek seconds) in 39.5hrs
= 292,000 per hour
= 4900 per minute
= 81 per second
That's an awful lot of errors to correct even though they aren't resent

Your Downstream SNR is too low, making your line unstable, lets hope ddDLM fixes this

Smix

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#1795110 6-Jun-2017 08:02

I guess it's just a waiting game to see if things get better I'll monitor for the next week or so and then post an update as an FYI to everyone; thanks for all your help!

xpd

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#1795592 6-Jun-2017 20:22

Interesting, appears Ive been tweaked :)

VDSL Training Status: Showtime
Mode: VDSL2 Annex B
VDSL Profile: Profile 8b
Traffic Type: PTM Mode
Link Uptime: 11 days: 16 hours: 5 minutes
============================================================================
VDSL Port Details Upstream Downstream
Line Rate: 13.751 Mbps 68.283 Mbps
Actual Net Data Rate: 13.666 Mbps 68.183 Mbps
Trellis Coding: ON ON
SNR Margin: 5.0 dB 4.5 dB
Actual Delay: 8 ms 6 ms
Transmit Power: -11.3 dBm 15.1 dBm
Receive Power: 0.0 dBm 6.1 dBm
Actual INP: 0.5 symbols 0.0 symbols
Total Attenuation: 0.3 dB 9.0 dB
Attainable Net Data Rate: 13.416 Mbps 65.358 Mbps

Dunno when it happened, I gave up keeping an eye out for it....... :)

Not quite the boost I was hoping for, but better than nothing :)

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

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freakngeek

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#1795613 6-Jun-2017 21:17

I got another ddDLM change this morning
Interleave Depth now over 800, up from 100 (week earlier was over 700 then dropped)
This dropped my actual DS connection from 50Mbps to 40Mbps

I'm not far from moving Modem close to road side pillar.
Solar panel 270w, Solar controller, Battery 100ah, cables and box to put it all in sorted
Antenna by house setup, POE cable running from house to Ubiquiti Powerbeam on a 4m pole (I'll bury the cable later)
Tomorrow 2x bags of easicrete to setup pole at road, antenna all setup ready to go
Ordered the steel Box section to make up frame for solar panel, got some welding to do.
Most awkward part will be making up POE CAT6 cable from DV130 modem to Antenna, I have to along the way inject 24v from 12 to 24v converter
Cat6 cable to RJ11 plug already made
Outdoor gel filled CAT6 cable is a pain the $%#^ to get RJ45 plugs onto
Just need to finalise where the antenna goes, need to do some signal strength testing before I dig the hole.

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