Large drop in VDSL sync speed, any suggestions?

Forums › Spark New Zealand (including Skinny and BigPipe) › Large drop in VDSL sync speed, any suggestions?

timbosan

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#144191 10-May-2014 12:09

I recently moved to BigPipe VDSL and as part of that had coffeebaron in to change my splitter from the ADSL one he installed a few years back, to a new VDSL one. As part of the move I also signed up for a VOIP service so I only have the VDSL modem on the line, and its a direct CAT5 run from the demarcation point.

When I moved to VDSL I was getting 10 up and 43 down, even before the new filter, and this persisted after the change in filters. This speed stayed constant for several weeks, however a few weeks ago I noticed the down sync speed had dropped to 31. I think this was after the modem went off (it was plugged into a socket and the PSU came loose). Since then I have restarted and powered down the unit, but no change.

Does anyone have any ideas as to what could cause this? Should I raise it as a fault to BigPipe, or is it more likely to be someone else on the cabinet with VDSL and no splitter? If so, is this the magnitude of change that can occur from no splitter on a line?

I am approx 200m from the cabinet, modem stats are:

Uptime:   5 days, 18:36:55
DSL Type:   ITU-T G.993.2
Bandwidth (Up/Down) [kbps/kbps]:   10,342 / 31,282
Data Transferred (Sent/Received) [B/B]:   0 / 0
Output Power (Up/Down) [dBm]:   429496723.1 / 13.5
Line Attenuation (Up/Down) [dB]:   20.4 / 9.2
SN Margin (Up/Down) [dB]:   14.3 / 12.3
System Vendor ID (Local/Remote):   TMMB / ----
Chipset Vendor ID (Local/Remote):   BDCM / IKNS
Loss of Framing (Local/Remote):   0 / 0
Loss of Signal (Local/Remote):   0 / 0
Loss of Power (Local/Remote):   0 / 0
Loss of Link (Remote):   -
Error Seconds (Local/Remote):   275 / 0
FEC Errors (Up/Down):   983 / 0
CRC Errors (Up/Down):   110 / 813
HEC Errors (Up/Down):   0 / 1,046

(Edited to fix my poor typing)

Jase2985

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#1041314 10-May-2014 12:54

you do realise that VDSL is a best effort service? i doubt your isp would waste there time with with a fault as its not faulty in their eyes.

what is your INP and delay? DLM may be a factor

timbosan

2159 posts

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#1041361 10-May-2014 15:46

Jase2985: you do realise that VDSL is a best effort service? i doubt your isp would waste there time with with a fault as its not faulty in their eyes.

what is your INP and delay? DLM may be a factor

Yes I do realise it is "best effort" and I not complaining at all, simply asking if this is indicative of a fault or if its just the way VDSL works when others join the cabinet. If you read the thread I started that asked if a master splitter if needed when you have naked DSL, there are references in that to lines without a splitter affecting others on the same circuit.

I don't know what INP and delay are, how do I find these? And I have never seen the line stats change whilst the modem is on (which is what I understand would happen with DLM), only when it powered off.

Lorenceo

904 posts

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#1041369 10-May-2014 16:01

You mentioned the modem being powered off. How often do you turn it off?
DLM expects the modem to be on 24/7. It's possible that if you're causing the modem to lose sync often that DLM may have put you on a more conservative profile.

It looks like you're using a Technicolor modem from the stats formatting.
To get the INP and delay stats you need to telnet into it.
Open command prompt and type telnet 192.168.1.254 (assuming that is your modem's IP address).
The username should be Administrator and the password should be blank. The username is case sensitive.
Once in type xdsl info expand 1, and it should show you your line stats, including delay and INP values.

Since you have already had a filter + CAT5 cable for the modem installed the best way to ensure the best VDSL sync stats is to leave the modem alone. Avoid disconnecting or power cycling it, and hope that DLM increases your speed.

timbosan

2159 posts

Uber Geek

#1041378 10-May-2014 16:16

Hi,

I don't power of my modem, however it did power off when the plug became loose (it was in a 4 way powerboard hanging vertically during some kitchen renovations). Since then I have only restarted it once and powered off once in an effort to try and fix it.

And yes Technicolor modem, I will do the TELNET soon. I always assumed DLM worked on improving speed, but I guess it could also drop the speed if it detects the modem dropping off?

Jase2985

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#1041585 11-May-2014 07:44

DLM works on improving ping/speed while maintaining a stable connection (minimal errors), the result is someone a small drop in speed though. 10mbps is a little extreme from what i have seen though

BigPipeNZ

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BigPipe

#1041977 12-May-2014 09:23

Hi,
sorry I didn't see this before.

What the others have said about DLM is correct. DLM can cause sync speed to go up or down depending on how the line is performing. A 10Mbps drop is larger than normal, but definitely not unheard of. I was syncing at around 60Mbps at one point, but now at 45Mbps.

Have you raised a support ticket yet? Might be worth doing that and one of our guys can take a look.
Probably worth just having a look at your filter too - make sure a mouse hasn't taken up home next to it and started nibbling the wires or something :D

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coffeebaron

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#1042020 12-May-2014 10:26

I have seen a number of VDSL connections drop back from the early days. Becoming more uncommon now to see connections over the 40's. Still worth getting it checked out, but if there was anything really wrong with it, you would see more disconnects and much poorer sync speeds.

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timbosan

2159 posts

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#1042065 12-May-2014 10:53

Thanks for all the info - I will raise a support ticket and see if anything shows up. If it was only 2-3Mb I wouldn't be concerned.

coffeebaron

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#1042106 12-May-2014 11:31

To get an idea of impact of other connections;
- get a UPS
- wait for a power cut
- reboot your router during a power cut
- enjoy the extra speed (for a while)

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Nebbie

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#1043849 14-May-2014 14:09

DLM (Dynamic Line Management) looks at a number of factors on the line to determine the best profile for the conditions of the line.

By sounds DLM was seeing errors on the line and the fact that the modem accidentally powered off would have tricked DLM into thinking there was another line "glitch" due to this it sounds like it changes your profile to best suit the line conditions.

If you were bordering changing profiles you may endup staying on this profile, as the more VDSL connections that go live on your copper bundle the slower the maximum speed your router can sync at.

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