In reply to a post by MrSaffron:

so the change to 80/20 shouldn't affect much?

It will increase crosstalk, because the sync is capped, and so at sync time the bit loading is lower. Cue 17MHz pushing more bits into each bin and using more power, so more cross talk.
Ahh, yes, hadn't thought the sync would change - cross talk is a pain.

Not saying it is the total story, but may be a contributor.
On the locking I know, and it is becoming a pain to help understand issues and see through bluster and bluff from those who probably have no idea of the difference between 6dB and 12dB.

The locking is a nightmare both for ISPs and for end users - its a shame Openreach didn't get Huawei to produce a very simple status page that the ISP could have talked a user through accessing.

May OR assumed the ISP would have the information on their management system and wouldn't need to ask the user - which is short sighted given the cost pressures ISPs are under. Reminds me of the old "USB frog" idiocity where the USB plug was the official NTE.

Edited by jchamier (Fri 28-Sep-12 18:36:41)

In reply to a post by BatBoy:

http://forums.thinkbroadband.com/plusnet/t/4161526-f...

Plusnet does not have a "creepy throttling system."

In reply to a post by jchamier:

In reply to a post by MrSaffron:

so the change to 80/20 shouldn't affect much?

It will increase crosstalk, because the sync is capped, and so at sync time the bit loading is lower. Cue 17MHz pushing more bits into each bin and using more power, so more cross talk.

Ahh, yes, hadn't thought the sync would change - cross talk is a pain.

I've noticed the same thing - that turning on 80/20 makes things worse for some people.

I should be specific here that the observations are that SYNC speeds are worse. While contention & traffic management issues may appear later, for now the issue is strictly about the 17a profile over the copper.

I haven't seen an obvious cause - but that statements above *must* have some impact. Bit loading is altering in some frequencies, and that is having some level of effect.

But crosstalk? Surely that would be a problem YOU experience when someone ELSE upgrades their own line. Why would your own line degrade when you are switched to 80/20 yourself?

For myself, I wonder if it is interplay between upstream & downstream. The biggest impact to most of the affected lines (*) is probably in expanding the upstream, and yet it is the downstream that suffers.

(*) - The kind of line I believe is affected most is the ones with service around the 40Mbps level, who can expand into the 50's, but actually drop to the 30's.

Whatever happens, it usually seems to trigger DLM into placing profile restrictions, and activating interleaving that was never needed before.

Not saying it is the total story, but may be a contributor.
On the locking I know, and it is becoming a pain to help understand issues and see through bluster and bluff from those who probably have no idea of the difference between 6dB and 12dB.

The locking is a nightmare both for ISPs and for end users - its a shame Openreach didn't get Huawei to produce a very simple status page that the ISP could have talked a user through accessing.

May OR assumed the ISP would have the information on their management system and wouldn't need to ask the user - which is short sighted given the cost pressures ISPs are under. Reminds me of the old "USB frog" idiocity where the USB plug was the official NTE.

On the other hand, many people don't understand the stats being presented, and use them as a whip to the ISP. Without the stats, there is less to use against the ISP. Perhaps they were hoping that the customers could be kept more docile?

It is probably a case of "damned if you do, damned if you don't".

Oh - and Huawei's status page, once unlocked, is wrong anyway - so would only have confused things! The error counts seem to come from the wrong stats.

In reply to a post by WWWombat:

I should be specific here that the observations are that SYNC speeds are worse. While contention & traffic management issues may appear later, for now the issue is strictly about the 17a profile over the copper.

But 17a was rolled out last year?

I remember on my old adsl line adsl2+ synced massively lower than adsl2 and a few on here couldnt understand why.

My guess is the extra US sync is causing issues on the DS sync. Of course extra cross talk may also be an issue.

In reply to a post by BatBoy:

In reply to a post by WWWombat:

I should be specific here that the observations are that SYNC speeds are worse. While contention & traffic management issues may appear later, for now the issue is strictly about the 17a profile over the copper.

But 17a was rolled out last year?

Yes - and I saw changes on my 40/10 package at that time. The shift in some of the bands gave a slightly bigger allocation to downstream at lower frequencies, and my line squeezed an extra 3Mbps from it.

However, everyone was still constrained to 40/10, so the bit-loading that the modems determined during sync was lower than now.

The observations NOW are that it is the change of constraint from 40/10 to 80/20 that does the damage, not the introduction of the 17a profile alone.

What you need to demonstrate that, is to have the stats from someone who is on 40/10 now and compare them with stats after they move to 80/20, especially if their sync has actually fallen after the move.

Which, as BT have locked the modems, is quite tricky

FWIW, The switch from 40/2 to 40/10 also has a negative effect upon DS sync speed for those connections that are unable to max out the 40Mb cap.

Plusnet & I experimented with 40/2, 40/10 & 80/20 on my "up to 1000m" connection.

These are typical results

Text
1 23 4	Service         DS sync speed 40/2             up to 35Mb40/10            up to 30Mb 80/20            up to 30Mb

Attainable DS Rate has been around 34Mb to 36Mb for all 3 services.

US sync speeds increased from 2Mb (capped) to around 5Mb on both the 40/10 & 80/20 services on my longer length connection.

So, for my connection, a 3Mb increase in US sync speed causes a 5Mb decrease in DS syncs speed.

A few other sub-40Mb users (not only Plusnet) have also mentioned the same effect on switching to a higher US service.

But 40/10 to 80/20 had no effect?