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45 posts

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# 105071 26-Jun-2012 20:29
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I've just moved to Chorus / Telecom as our home line provider and now have FYX as the ISP. I live in Blockhouse Bay in Auckland and according to the Chorus maps at http://www.chorus.co.nz/maps we are supposed to be in a >10Mbit zone with an UFB connection being way off into the future (probably 4 years out). Our sync rate is currently only 5.5Mbit which seems really low for the line attenuation we have.

FYX lodged a fault with Chorus to try and understand why we only sync at 5.5Mbit with a SNR margin of 12dB and line attention of 32dB. On the Vodafone Red Network we were on a profile with a 6dB SNR margin that gave us an 8Mbit connection.

Geekzone speed test with Chorus / FYX below.



Chorus's response:
"You were probably on the red network.
TCNZ completed. Investigated. There is no profile on the TCNZ network that has a Target Noise Margin of 6db. All standard profiles have Target Noise Margin 12db. Currently the customer modem has DSL sync rates 5562/945 kbps which is in line with the neighbouring connections. The port shows the connection is stable and error free. No further action required."

According to everything I've read we should probably be syncing at much more than 5.5Mbit for an ADSL2+ connection with a line attention of 32dB (maxing out at ~14Mbit). http://en.wikipedia.org/wiki/File:ADSL_Line_Rate_Attenuation.gif

Chorus came out a while ago (when we were on Vodafone) and did a line test where the phone line enters the house and synced to the Vodafone DSLAM at just over 8Mbit, which is what our modem used to also sync at once I put in a master line filter and a dedicated Cat6 line to the modem.

Does anyone have any suggestions on how to get someone to look into whether there is anything obviously poked on the wire between us and the exchange, which is apparently only 1.4km away. Or is this sort of speed actually OK for a 32dB line attenuation?

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  # 646660 26-Jun-2012 21:05
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Looks a little slow to me, here is our averages for that sort of distances (km:Mb/s)

1.39.21.47.61.58.9
That's 18 probes 4,6 and 8 respectively, making this a reasonable stat.  These are all at 5am, when traffic is at the lowest.  FS/FS ADSL, today.

Of these probes, one is showing less than 5Mb/s and 3 are <6Mb/s, but with 6 greater than 10Mb/s.   Accuracy of the distances being a critical factor here, getting an exact cable distance, let alone cable type is difficult.

A lot will depend on your setup as you suggest, but the cable type may also make a difference.

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  # 646663 26-Jun-2012 21:13
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So your current setup is a master filter? Are you sure this is wired correctly and isn't possibly faulty?


 
 
 
 




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  # 646669 26-Jun-2012 21:30
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I believe the master filter install is fine. With it installed the modem connected at just over 8Mbit, identical to what the Chorus test equipment connected at directly at the POE (when we were with Vodafone).

We only just moved over to FYX and the only difference now is a Telecom / Chorus home line and a larger SNR margin.

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  # 646672 26-Jun-2012 21:34
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What models of modems have you tried?




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  # 646677 26-Jun-2012 21:41
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Over the years we've had a 3Com Office Connect, Linksys X3000 (wouldn't recommend this to anyone) and now we have a Netgear DGN2200. I don't recall any significant difference in the connect rate for any of them. We are trying to stream more video content now though and throughput has become pretty important for that. At the moment we can't stream anything more than 720p.

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  # 646702 26-Jun-2012 22:17
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As you've probably realised already, this is just the result of a "safe" DSL profile being used by Chorus whereas Vodafone may have been using a more "aggressive" profile.

Aside from any wiring faults in your house, which are largely negated by your master filter anyway, there's not much you can do unfortunately, unless you can convince them to use a more aggressive profile.  Sometimes non-interleaving profiles have a tendency for lower SNR margin targets, if that helps.

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  # 646752 27-Jun-2012 03:12
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32dB line attenuation with 12dB noise margin should get a line rate around 10Mbit I would have thought.

If you have a master splitter/filter isolating your dsl jack from your internal wiring and the ISP via Chorus has tried port reset, re-termination of the line at the exchange/cabinet, tried moving your line to a different port/line card... then it's probably down to dodgy phone cable between you and the exchange/cabinet.

 
 
 
 


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  # 646852 27-Jun-2012 10:03
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In a previous post of mine my stats were 34dB/12dB and i was getting 8377/945 (smc7904 router).
re-ran everything today and i get the following (dynalink rta modem):

callplus adsl connection stats




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Vocus

  # 646870 27-Jun-2012 10:27
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The chosen Sync speed for a given DSL circuit is based on SNR (Signal to Noise Ratio) not purely attenuation (although it is one factor, as it reduces Signal levels).

So if you have a noisy line, given the same attenuation, SNR is lower. Therefore, sync speed will be lower for a given SNR margin.

It's quite possible that a different modem will give you higher sync speed.  Or there could be an iffy joint between your house and the exchange/cabinet; although usually this would increase attenuation too and show up on a line test.  Or the copper is just old and sketchy.

Try different modems.

Maybe you have some appliance in your house producing noise on the line, try turning off fridges, freezers, air conditioning, flourescent lighting to see if makes any difference (try resetting the modem in each case).  

Eliminate any extension cords between the DSL jack and your modem.

Double check all the crimps on the master filter.

Good luck!

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  # 646935 27-Jun-2012 12:30
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Just a note regarding changing ADSL2+ service profiles:

Your Internet Service Provider decides what service profile is configured on your ADSL2+ line - not Chorus.

ISPs will order the profile that matches the service proposition they want to offer.  Making changes to service profiles is not without consequences.  As has been hinted at by other posters to this thread, there is a trade-off between raw speed and stability/performance that needs to be made.

Your ISP is the right person to have this discussion with - not all ISPs support all available service profiles.





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  # 646957 27-Jun-2012 12:51
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ChorusVan: Just a note regarding changing ADSL2+ service profiles:

Your Internet Service Provider decides what service profile is configured on your ADSL2+ line - not Chorus.

ISPs will order the profile that matches the service proposition they want to offer.  Making changes to service profiles is not without consequences.  As has been hinted at by other posters to this thread, there is a trade-off between raw speed and stability/performance that needs to be made.

Your ISP is the right person to have this discussion with - not all ISPs support all available service profiles.



Very true this.  Have you tried asking the ISP if they can request a different profile?



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  # 647096 27-Jun-2012 16:31
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Just got off the phone to FYX support. Interleaving is getting turned off today so I'll see if that makes any difference. Not holding my breath.

FYX have already asked if Telecom could move me to a lower noise margin and were told no. So I guess FYX isn't an ISP that can't negotiate with Telecom / Chorus (whoever owns the hardware in the exchange and makes the decision) to move me to a more performant profile.

I wish I knew more about how all this worked before I moved to a different DSLAM hardware provider. Would have known what questions to ask before jumping off the ISP I was already with.

Telecom have already stated that our current sync rate is in line with "neighbouring connections" so it's looking like it's probably something that is related to the wire between us and the exchange rather than anything internal to the house.

Doesn't feel like I'm going to be able to stream anything more than 720p content unless I move to another ISP that owns there own DSLAM equipment who are able to go down to a 6dB noise margin to eek out a few more Mbit.

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  # 647108 27-Jun-2012 16:49
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dteirney: Just got off the phone to FYX support. Interleaving is getting turned off today so I'll see if that makes any difference.


Well, if the SNR margin remains same, so should your Sync speed. But actual performance should improve, so see how you go.  Be interesting to know how much difference it makes in the "real world" for your situation, try a speed test and a stream now and compare results after the change...

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# 647174 27-Jun-2012 18:52
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... Chorus has tried port reset, re-termination of the line at the exchange/cabinet, tried moving your line to a different port/line card... then it's probably down to dodgy phone cable between you and the exchange/cabinet.


I believe that is exactly what is being asked. How to get Chorus to do the 'port reset, re-termination, moving port/line' etc without simply closing the ticket as done previously?





Please keep this GZ community vibrant by contributing in a constructive & respectful manner.




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  # 647287 27-Jun-2012 22:42
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I've done some research and I've found that the modem has some say on what the noise margin will be used regardless of what the DSLAM profile is set to.

For my Netgear DGN2200 router the following puts the router into debug mode which allows a telnet login:

192.168.1.1?setup.cgi?todo=debug

Then you can configure how the snr margin is determined. The number in the command below is a percentage, e.g. 100 is 100%, 50 is 50%. I've tested various percentages to get down to a 6.7dB noise margin which has resulted in a 2Mbit increase in connect speed up to 7.6Mbit.

adslctl configure --snr 100

Reasonably good increase in throughput as well.



This doesn't really address why we have such average sync rates to start with but at least claws us over the threshold for making streaming of 1080 content within the realms of possibility depending on how good the international traffic throughput is with FYX / Maxnet.

Interleaving doesn't look like it will get turned off until tomorrow. Perhaps that will help as well.

I'll have to monitor for the next few days and see if the connection is still stable. We didn't have any problems with Vodafone at 6dB SNR margin so hopefully it will be fine.

More information at http://www.e-eeasy.com/netgear-router-problems.aspx if anyone is interested.


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