Is anyone else experiencing this issue?: ADSL2 - Fast Downstream, Slow Upstream

Forums › New Zealand Broadband › Is anyone else experiencing this issue?: ADSL2 - Fast Downstream, Slow Upstream

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#284473 21-Dec-2009 21:09

I finally got around to trying a TP-Link TD-8840, these are broadcom chipset and i've seen them recommended a few times here on gz.
860kbps upstream!

cyril7

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#284482 21-Dec-2009 21:44

Good one, can you post the full stats.

Cheers
Cyril

cyril7

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#284483 21-Dec-2009 21:44

Good one, can you post the full stats.

Cheers
Cyril

boykunk

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#284711 22-Dec-2009 21:17

I have a ASUS router which uses TI chipset.

Ds Rate (Kbps)

10643

Us Rate (Kbps)

1023

DS Margin

12

US Margin

12

DS Line Attenuation

27

US Line Attenuation

13

Trained Modulation

ADSL_2plus

LOS Errors

0

Peak Cell Rate

2412 cells per sec

These are my minimum rates. and I'm approx 500m from the local cabinet.
Maybe you want to have a look.

SamF

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#284712 22-Dec-2009 21:22

Hmm, 10meg seems a little low considering your upload is so high... but I guess ADSL2 drops off pretty fast with added distance.

boykunk

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#284792 23-Dec-2009 10:58

SamF: Hmm, 10meg seems a little low considering your upload is so high... but I guess ADSL2 drops off pretty fast with added distance.

sure does

.
so make sure you buy a house next to the exchange LOL

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cyril7

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#284796 23-Dec-2009 11:11

Hi, an attenuation of 27dB implies around 2km of cable for which 10-12Mb/s is what you should expect.

ADSL1 can maintain pretty much full sync rate out to around 2-2.5km so you should see speeds of 7.6Mb/s etc out to that distance then it tails off.

ADSL2 can maintain full 1.1MHz spectrum out to the same 2-2.5km so you should see 10-12Mb/s out to that distance then it tails off.

ADSL2+ can maintian pretty much full sync speed(18-24Mb/s) out to around 1km then it begins to tail of to around 10-12Mb/s at 2-2.5km and onward down from there.

Also note that Telecom has configured their ADSL2+ DSLAMs to target 12dB Downstream noise margin, this means you should get a more stable and consistant connection but you are unlikely to ever see more than 20Mb/s (ie no 22-24Mb/s rates) even if you are pretty much on top of the cabinet.

Orcon and Vodafone by contrast configure their DSLAMs to target 6dB noise margin, this has the potential of being less stable with noise etc but will allow sync rates for short tails close to the 24Mb/s max.

ADSL1 was designed with forward error correcting technology that needed 12dB noise margin to work correctly. ADSL2/2+ on the other hand uses more powerful forward error correction that enables it to work successfully with as little as 6dB noise margin. That said Telecom have I believe sensibly kept the 12dB noise margin on their ADSL2/2+ product. I would prefer a stable but slightly slower connection that the other way around.

@boykunk, it would seem that either you have poor joints onyour lines or unfiltered phones across the line that are artificially increasing the line attenuation, hence reducing your max sync speed, or your local telecom line distribution does a run around the block before it gets to you. The latter is not uncommon as the cables were originally laid out for voice(POTs) service where a 5-6km line was considered acceptable.

Cheers
Cyril

SamF

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#284898 23-Dec-2009 20:07

My downstream attenuation is around 12db and I'm ~200m from the cabinet (~600m cable length based on my ADSL1 attenuation figures), however every ADSL2 modem I've ever used gives me 15mbit max downstream sync. Sure 15mbit is nothing really to complain about, however being so close I actually expected to get a higher rate than what I seem to be able to achieve.

cyril7

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#284924 23-Dec-2009 22:29

Hi, 15dB attenuation and 15Mb/s are pretty much par for the course, so if you are not 800-900m from the cabinet and so have an artifically high attenuation then check you house wiring, 99% of DSL issues end with house wiring issues.

Cyril

SamF

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#284936 23-Dec-2009 23:46

You think my attenuation should be lower based on my distance from the cabinet?

cyril7

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#284961 24-Dec-2009 09:44

Hi, 15dB is just over 1km of cable. As I have said before this may well be the case as the cable may do a run around the block to end up 200m down the road. For 15dB of attenuation a sync rate of 15Mb/s is about right. So the only point of dispute you may have is that the cable length/attenuation "appears" higher than you anticipated.

So either its right and doing a run around the block and thats the end of story, or there are bad joints in the street distribution feeder (which involves line staff to do checks at your expense so that wont happen) or something in your house wiring is artificially increasing the loss on the line. The only way you can reliably test that is to disconnect all your house wiring at the demarc, attach your modem there and check, if its significantly better then you need to install a central filter etc.

Tell us about the house wiring, how many phone points, whats connected, are they all filtered etc etc.

Cyril

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SamF

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#284991 24-Dec-2009 13:20

Well, my attenuation is 12db, not 15 if that makes any difference.

I have naked DSL (Fusion) and the only thing plugged into my line is the ADSL modem, no filters or anything else. House alarm has been disconnected already. Telecom have done speed tests at the demarc point & inside the house before with no significant differences in speed.

cyril7

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#284992 24-Dec-2009 13:23

OK, sorry I dont know where I got 15dB from, I would have expected higher sync rates if thats the case, but hey, they are only obliged to supply 10Mb/s or more.

Cheers
Cyril

SamF

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#284995 24-Dec-2009 13:54

Hmm, interesting. My line has had history of being a bit unpredictable, however Telecom can never seem to find anything conclusively wrong with it. Oh well [shrug], I guess I'll just have to 'settle' for 15mbit.

I can actually get 1.5megaBYTES per second download so that's not too shabby!!

boykunk

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#292167 22-Jan-2010 13:10

@boykunk, it would seem that either you have poor joints onyour lines or unfiltered phones across the line that are artificially increasing the line attenuation, hence reducing your max sync speed, or your local telecom line distribution does a run around the block before it gets to you. The latter is not uncommon as the cables were originally laid out for voice(POTs) service where a 5-6km line was considered acceptable.

This reply might be late, but I just like to mention that I have rented two properties next to each other. While a new property syncs me to 9xxxkbps. Where as the property im living now is about 20+ years old and it syncs at 10xxx~11xxx kbps.
So i think its to do with the distance around where i live instead of house wiring. I think, because i'm not some electrician.

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