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Annex M Issue

craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Annex M Issue

Good afternoon,
I've discussed this on the phone, but wish to open a longer term line of communication as things get sorted out.
My business broadband line went live today, and I selected Annex M as I was signing up (this was the only reason I went with PlusNet). I am syncing at ~1170kbps, which is what I would expect from ADSL2+ Annex A (this is what I got with my previous supplier). If I force Annex A from the router, I get the same. If I force Annex M, it never syncs, leading me to believe that Annex M was not enabled.
The helpful rep on the phone told me that it is enabled. When I told him that I couldn't sync when forcing Annex M, he offered to remove then re-add Annex M from the line, which should sort it within a couple of working days - I will report back as this progresses.
What has concerned me is something the rep said on the phone - he said "I've never seen an Annex M line above 1.5mbps". This is not what I expected from the marketing of business broadband, which stated a max of 2.5mbps. I have a short line, with attenuation of 22.5 down, 12.6 up, so I would expect to get more than 1.5 - hopefully a little more than 2.0. If 1.5 really is the most I can expect, then it feels like a bit of a con. Hopefully this is not the case, and when this issue is sorted out I will be satisfied with my upstream sync speed, we shall see.
Does anybody have any experience with this that they wish to share?
Many thanks,
Craig Hughes.
32 REPLIES
kitz
Rising Star
Posts: 817
Thanks: 46
Registered: 08-06-2007

Re: Annex M Issue

I would never recommend Annex_M for a line that can only sync at 1170 on adsl2+  Shocked
What youre doing is taking away from the downstream and giving to the upstream. So youre losing tones 33-59 which without seeing your line stats and based on annex-a sync will leave you very little to play with.  This could perhaps be the reason why you cant sync at all on annex-m.

>>> "I've never seen an Annex M line above 1.5mbps
Poppy cock.  I used to sync at the full 24Mbps down and 2.6Mbps up.  Annex_M works best on short lines, it doesnt work on long lines.
Seeing your line stats would give a better view of the situation, so it may be an idea to post them.
If the line is set as annex-m on the dslam, then its entirely possible to force annex-a with some routers.  I used to be able to on my Be-box.  You cant force annex-m though unless its set at the dslam/msan. 
craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Re: Annex M Issue

Apologies for the confusion, that 1179 kbps is my upstream sync. Downstream sync is about 19000 kbps with a 6.0dB margin. From what I've read, the line is a prime candidate for decent Annex M gains (not as good as yours was though!).
Full line stats as of now:
ADSL Link Downstream Upstream
Link Rate 18823 Kbps 1179 Kbps
Line Attenuation 22.5 dB 12.6 dB
Noise Margin 6.0 dB 6.8 dB
Good to know that it's possible to sync so fast. From what you said about not being able to force Annex M, it sounds like it's not set at the dslam/msan yet. Hopefully this will resolve in a few days.
Thanks for the input,
Craig.
kitz
Rising Star
Posts: 817
Thanks: 46
Registered: 08-06-2007

Re: Annex M Issue

Apologies.  I did indeed think it was your downstream. Embarrassed
Looking at your stats, yes it should work well for you Smiley 
You will lose appx from your downstream what you will gain in your upstream.  Power cut back and PSD masks are applied to avoid cross talk so a lot of the tones arent fully bit loaded on annex-m, but you should be fine and easily getting far more than you are now.  Definitely sounds like its not set on the dslam yet.
I was at 3dB SNRm which is what allowed me to just about eke full sync both up and down. iirc 6dB gave me circa 2.4 Mbps.  Interleaving also knocks a bit more off.
Community Veteran
Posts: 38,460
Thanks: 1,027
Fixes: 62
Registered: 15-06-2007

Re: Annex M Issue

This is about what happens to the tones in use http://community.plus.net/forum/index.php/topic,120275
craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Re: Annex M Issue

Quote from: kitz
Apologies.  I did indeed think it was your downstream. Embarrassed
Looking at your stats, yes it should work well for you Smiley   
You will lose appx from your downstream what you will gain in your upstream.   Power cut back and PSD masks are applied to avoid cross talk so a lot of the tones arent fully bit loaded on annex-m, but you should be fine and easily getting far more than you are now.   Definitely sounds like its not set on the dslam yet.
I was at 3dB SNRm which is what allowed me to just about eke full sync both up and down. iirc 6dB gave me circa 2.4 Mbps.  Interleaving also knocks a bit more off.

Great to hear that it should work well, looking forward to it activating. I understand the downstream bandwidth trade-off and consider it more than worth it for a 100%+ upstream increase.
Regarding your 3dB SNRm - is that something that plusnet will set for me? My previous provider would not go below 6 dB, and tweaking it myself via the router only changed my downstream (which remained stable WAY below 6 dB). If plusnet allow a "maximum throughput" profile of 3 dB then that's another reason to be happy Smiley
Thanks again,
Craig
andy265
Grafter
Posts: 78
Registered: 30-08-2012

Re: Annex M Issue

I'll add another vote for getting over 1.5MB upload with annex M. Our office line is about 200m long and it currently connected at 19252 down, 2307 up.
kitz
Rising Star
Posts: 817
Thanks: 46
Registered: 08-06-2007

Re: Annex M Issue

Quote from: Oldjim
This is about what happens to the tones in use http://community.plus.net/forum/index.php/topic,120275

Interesting thats OJ..  and exactly why its not good on long lines.
Your graph also shows a perfect example of the effects of power-cut back and the psd mask for annex m that ensures less bit loading in tones 33-59 that I mentioned in my earlier post.
My attenuation was 7dB so I was ok.  Im on FTTC now, but I may still have some graphs somewhere.
kitz
Rising Star
Posts: 817
Thanks: 46
Registered: 08-06-2007

Re: Annex M Issue

Quote from: craighughes16
Regarding your 3dB SNRm - is that something that plusnet will set for me? My previous provider would not go below 6 dB, and tweaking it myself via the router only changed my downstream (which remained stable WAY below 6 dB). If plusnet allow a "maximum throughput" profile of 3 dB then that's another reason to be happy Smiley

BTw do a 3dB profile for 21CN, but your line has to be pretty stable for it to work.    My line was pretty boring and would flatline for months on end at 3dB.  It never moved nor gave any errors. 
If your SNRm fluctuates a fair bit,  then 3dB isnt such a good idea.  ADSL (2/2+) needs 3dB of SNR to load one bit, so if your line drops much below 3dB of SNRM then you start to see errors and bitswaps and the DLM will soon kick in again and take you back up to 6dB.
craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Re: Annex M Issue

It has now been three days since my Plusnet service went live, and I'm still syncing at Annex A upload speeds. I'm hesitant to force annex M via my router as it hasn't worked previously and I don't want to mess up the line training by constantly fiddling.
Could somebody please look into this? I have paid for the add on when I signed up, so I would like to be able to use it ASAP.
Many thanks,
Craig Hughes
goldenfibre
Aspiring Pro
Posts: 2,627
Thanks: 52
Fixes: 2
Registered: 01-06-2010

Re: Annex M Issue

Quote from: craighughes16
Full line stats as of now:
ADSL Link Downstream Upstream
Link Rate 18823 Kbps 1179 Kbps
Line Attenuation 22.5 dB 12.6 dB
Noise Margin 6.0 dB 6.8 dB

How come your Line Attenuation is short than mine but I getting 1279K on upstream as my line attenuation (upstream) is 17.0dB very odd to see your upstream sync below than mine?
craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Re: Annex M Issue

Do you have Annex M enabled?
If not, I'm not sure, bu that's a separate issue that I will deal with once I have Annex M properly enabled. Looking at the StreetStats on Uswitch however, my upload speed is in line with what others are getting in my area (approx 1.02mbps).
Thanks for your input,
Craig Hughes
goldenfibre
Aspiring Pro
Posts: 2,627
Thanks: 52
Fixes: 2
Registered: 01-06-2010

Re: Annex M Issue

No, mine isn't Annex M as I didn't ask for it cos no need for that because it will cost you extra charge for Annex M from BT Wholesale to Plusnet and also reduced your downstream sync rate too. I just requested uncapped upload and I get from 445K to 1279K.
craighughes16
Grafter
Posts: 30
Registered: 23-11-2013

Re: Annex M Issue

OK, well perhaps your line holds a 3dB noise margin without issue? That would probably give you the higher sync. My line is training and still on 6dB, so perhaps it will improve in a week or 2.
If you have a 6dB noise margin, higher attenuation and a higher sync speed, then I'm truly at a loss, but we're talking about a relatively small difference compared to the gains I should get from Annex M, therefore getting that successfully enabled is my priority at the moment.
Can anyone from Plusnet give me an update on the activation of Annex M on my line? Do I need to do anything on my end or should resync happen automatically and Annex M get auto-sensed by the router?
Thanks again,
Craig Hughes.
goldenfibre
Aspiring Pro
Posts: 2,627
Thanks: 52
Fixes: 2
Registered: 01-06-2010

Re: Annex M Issue

SNR of 3dB is nothing to do with upstream. It only applied to downstream only. My upstream SNR is 7.1dB and still 1279K. Before I used to be on downstream snr of 6dB and still on 1279K upstream.