Massive bandwidth drop after change of plan from 150GB to 500GB

Forums › Spark New Zealand (including Skinny and BigPipe) › Massive bandwidth drop after change of plan from 150GB to 500GB

darac

4 posts

Wannabe Geek

#151054 12-Aug-2014 14:07

Hi everyone,

I just wanted to ask you guy if anyone else has experienced massive bandwidth drop after changing plan from 150GB to 500GB on Telecom (Spark) UltraVDSL?

My bandwidth dropped from 50-60Mbps to 33Mbps which is just ridiculous. I have around 8 years of experience with DSL and other types of WAN technologies, so I know what I'm doing and this kind of bandwidth drop makes me think they changed profile on their DSLAM, but they won't admit it.

NM and attenuation:

Line Attenuation (Up/Down) [dB]:

12.9 / 6.1

SN Margin (Up/Down) [dB]:

14.7 / 13.3

Any thoughts or can anyone help me with this?

Cheers

D

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#1107056 12-Aug-2014 14:07

Hello... Our robot found some keywords in your post, so here is an automated reply with some important things to note regarding broadband speeds.

If you are posting regarding DSL speeds please check that

- you have reset your modem and router

- your PC (or other PCs in your LAN) is not downloading large files when you are testing

- you are not being throttled by your ISP due to going over the monthly cap

- your tests are always done on an ethernet connection to the router - do not use wireless for testing

- you read this topic and follow the instructions there.

Make sure you provide information for other users to help you. If you have not already done it, please EDIT your post and add this now:

- Your ISP and plan

- Type of connection (ADSL, ADSL2, VDSL)

- Your modem DSL stats (do not worry about posting Speedtest, we need sync rate, attenuation and noise margin)

- Your general location (or street)

- If you are rural or urban

- If you know your connection is to an exchange, cabinet or conklin

- If your connection is to a ULL or wholesale service

- If you have done an isolation test as per the link above

Most of the problems with speed are likely to be related to internal wiring issues. Read this discussion to find out more about this. Your ISP is not intentionally slowing you down today (unless you are on a managed plan). Also if this is the school holidays it's likely you will notice slower than usual speed due to more users online.

A master splitter is required for VDSL2 and in most cases will improve speeds on DSL connections. Regular disconnections can be a monitored alarm or a set top box trying to connect. If there's an alarm connected to your line even if you don't have an alarm contract it may still try to connect so it's worth checking.

I recommend you read these two blog posts:

- Is your premises phone wiring impacting your broadband performance? (very technical)

- Are you receiving a substandard ULL ADSL2+ connection from your ISP?

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Andib

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#1107071 12-Aug-2014 14:19

VDSL profiles are automatically selected via DLM which chooses which profile it thinks is best for you.

If you've restarted your modem quite a few times this could have caused the DLM to see your line as unstable and compensate by putting you on a lower profile (Such as 8B).

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hio77

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Lizard Networks

#1107075 12-Aug-2014 14:27

sounds like your line has dropped from a 17a bandplan to 8b.

likely cause is iver, a port reset or line instability.

good news is, your attenuation looks to be low enough that you can get back onto 17a. you do have a minimum 90 day wait ahead of yourself however.

i wouldnt put too much blame on the CSRs, many of them dont quite understand VDSL and DLM, or do not care to dig into it too much.

as you have 8 years of experience, ild expect you would be able to present evidence that yes this has happened however..

put simply, your now in the 90day wait period, until your line will be considered for 17a. enjoy the joys of DLM managing a line. VDSL is not an assured product, you cant be locked into a single profile.

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sidefx

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#1107078 12-Aug-2014 14:30

Andib: VDSL profiles are automatically selected via DLM which chooses which profile it thinks is best for you.

If you've restarted your modem quite a few times this could have caused the DLM to see your line as unstable and compensate by putting you on a lower profile (Such as 8B).

This.

Sounds very much like a drop from 17a to 8b by DLM. DLM is automated, so it's not like "they" did it on purpose (or even accidentally)

Have a read of this if you haven't already, it applies to all VDSL offerings in NZ:

http://www.geekzone.co.nz/forums.asp?forumid=90&topicid=105744

(some of the modem stuff is fritzbox specific, but the basics are all the same)

EDIT: Lol, beaten to it, damn you hio77 :P

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hio77

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#1107082 12-Aug-2014 14:33

sidefx:

EDIT: Lol, beaten to it, damn you hio77 :P

i can only try...

i missed the first post... damn having to do some housework! damn!

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RunningMan

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#1107087 12-Aug-2014 14:49

That downstream noise margin is higher than the 12.0dB target, which suggests there was previously more noise on the line than there is now. Fluctuating noise levels can point to intermittent external interference or physical wiring issues like joint failures or moisture ingress.

How are you measuring the bandwidth - DSL sync rate, or throughput?

If it were the ISP (or something else external) reducing bandwidth then you would see a throughput drop but DSL sync remain the same.

Cbfd

307 posts

Ultimate Geek

#1107101 12-Aug-2014 15:40

Sounds like some more people in your area have vdsl causing a drop in speed :)

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darac

4 posts

Wannabe Geek

#1107130 12-Aug-2014 16:12

Hi,

Thanks for all the replies. It does sound like DLM has changed the profile, but I must say that I'm a bit surprised about that 90 day period. That sucks. They must be able to change it manually though...

However, profile change will change DSL sync which also did in this case. That so odd. I had my modem reset more times than today and the profile never changed...

Anyway, thanks again.

sidefx

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#1107131 12-Aug-2014 16:17

darac: Hi,

Thanks for all the replies. It does sound like DLM has changed the profile, but I must say that I'm a bit surprised about that 90 day period. That sucks. They must be able to change it manually though...

This is something Chorus would have to do. They used to do it when VDSL was first released (a few people on these forums managed to get themselves put onto 17a manually) but I believe they don't do it any more and haven't for a couple of years - A number of people have tried and been refused AFAIK. I don't think it's something the ISP can do. Currently you just have to let DLM run it's course (I think the most you can do is get DLM reset but that won't get you back onto 17a and you'll just have to wait anyway)

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hio77

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#1107132 12-Aug-2014 16:19

heres a quote, of what it takes to obtain 17a,

BMarquis:

We have a number of conditions that must be met for your line to be switched to a 17a Spectrum profile.
If your line is on the 17a spectrum profile, but the spectrum between 8Mhz and 17Mhz is not being used, I'd be looking at your CPE. it shouldn't report 17a unless the DSLAM is providing that, and we run 8b and 17a on independant profiles.

As for the question of 'what allows a line to be on 17a':

The current bandplan is 8b (goes without saying!)
The line is shorter than 350 meters, which is an electrical length in the 5530 Network Analyser of <7dB
DLM is in operation on that line
A Bandplan switch hasn't occured in the last 90 days (to stop bouncing between 8b+17a, while still allowing re-evaluation as/when required)

vdsl is a managed service through DLM to insure the "best mixture" of stability and performance, there is no manual element to it.

while resetting the port/dlm is likely to reduce that 90 day wait, it is working by design.

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hio77

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#1107133 12-Aug-2014 16:20

sidefx:
darac: Hi,

Thanks for all the replies. It does sound like DLM has changed the profile, but I must say that I'm a bit surprised about that 90 day period. That sucks. They must be able to change it manually though...

This is something Chorus would have to do. They used to do it when VDSL was first released (a few people on these forums managed to get themselves put onto 17a manually) but I believe they don't do it any more and haven't for a couple of years - A number of people have tried and been refused AFAIK. I don't think it's something the ISP can do. Currently you just have to let DLM run it's course (I think the most you can do is get DLM reset but that won't get you back onto 17a and you'll just have to wait anyway)

ISPs cant request DLM or bandplan profiles to be locked in place anymore, so yep.. its all up to DLM!

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coffeebaron

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#1107207 12-Aug-2014 18:23

I am appropriately adjusting PeterReader's reply:

PeterReader: Hmm, here we go again. Another post on VDSL speed drops

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hio77

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#1107228 12-Aug-2014 18:52

coffeebaron: I am appropriately adjusting PeterReader's reply:
PeterReader: Hmm, here we go again. Another post on VDSL speed drops

who would have thought!

although atlest this one isnt a generic crosstalk drop in speed!

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darac

4 posts

Wannabe Geek

#1107670 13-Aug-2014 14:19

I finally got a hold of someone useful from Spark's second level support. They were able to reset port and DLM which increased my bandwidth a bit. Now running synchronized with 41Mbps. By looking at line statistics I'm sure the line would sync with even better max DL if it wasn't limited by some preset profile. I'm sure that this "DLM" used isn't that dynamic as everyone thinks.

However it's better than it was yesterday. Thanks again everyone

hio77

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#1107778 13-Aug-2014 16:54

darac: I finally got a hold of someone useful from Spark's second level support. They were able to reset port and DLM which increased my bandwidth a bit. Now running synchronized with 41Mbps. By looking at line statistics I'm sure the line would sync with even better max DL if it wasn't limited by some preset profile. I'm sure that this "DLM" used isn't that dynamic as everyone thinks.

However it's better than it was yesterday. Thanks again everyone

the D in DLM stands for dynamic. i suppose that makes it pretty dynamic eh?

DLM is very dynamic, in the sense, if it detects a move is likely to help the end user have a better balance of performance and stability it will.

Often we simply it a tad when talking about it, who wants to understand all the technical details about it afterall...

sounds like DLM pulled right back, which is a common thing for it to do. resetting it kicked it into gear for it to jump back to 41Mbit.

41Mbit isnt a bad sync on 8b, 50Mbit is about the max you will ever see, with very very few lines breaking over 50.

17a with its extra spectrum allows it to hit the slightly higher speeds, but you need to be lucky enough to roll over onto that profile first.

to recap what i said in an earlier post, your are likely to get back that 17a profile. its how long it takes that will likely be an issue for you. there is no manual switch a CSR can flick for you.

#include <std_disclaimer>

Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

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