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[plexy]

Hi folks,
Im moving toward bonding several lines from different providers to provide higher throughput and resilience (I am very well versed in the challenges here and have the correct equipment inside of each ISPs network already). I had some ISPs in mind, due to that fact. so thought id give a newbie a go as well, as its was only 24 a month including the line rental for 80/20.

As Kitizens may remember, I was with Plusnet and then later with BT infinity. As noted in my post at the time, I noticed the physical line sync speed went up some 10% (or there abouts) when we went from Plusnet to BT - with plusnet it was a solid 69 sync (since the pair swap) and then the day we migrated to BT it went to high 78+. That was about 14 months back.

We have today moved from BT to SSE. The only thing that changed is the provider, no one worked on the pairs.

max sync dropped 10%, back down to 69.

If nothing has changed on my line, but the provider which makes no difference to the copper loop, then why is the sync changing? In a way that appears to favor BT retail

[William Grimsley]

It could well be that different providers are using different DLM speed profiles, or it could be that you are seeing the line in a DLM reset state which can happen when you are changing from an ISP that has a different speed profile to the previous one. Also, it could be due to the line being activated at different times of the day as well as different line conditions. What I do know for a fact is is that no ISP has preferential treatment when it comes to line rates.

[plexy]

Thanks William that does make sense. Speed profile wise it should be the same, all three were 80/20 service so would there be a delta there at the vdsl level?

The BT HH5 was left in overnight during the cutover. BT released and Daisy took over - HH5 caught sync near as soon as provisioning was finished and the initial max speed it trained at was a significant drop from the cutover in provider. The same thing happened, but in reverse, when we started with BT 14 months ago. I thought last time it may have just been a fluke or DLM / profile related issue so kept a special eye out for just this kind of event this time round - which i was a little surprised to see.

there does not have to be a deliberate or known act for any advantage - or 'feature' - to be caused. While you can assure me there is no architected advantage from your own knowledge, can you vouch there are no bugs or configuration issues that could cause something that appears to make it look like this occurs?

[William Grimsley]

I'm not sure, maybe someone else can have a say in this?

[ejs]

By DLM profile, it's a setting, there's a choice of Speed, Standard or Stable (those are the Openreach names). It's not easy to reliably find out which one an ISP uses. Not helped by the three options sometimes being called Standard, Stable and Super Stable or something like that by BTWholesale.

[j0hn]

Williams comments are pretty accurate, and there is no preferential treatment from any ISP with regards to sync speed. Before your switched from Plusnet, was the sync at a fixed rate? do you have access to line stats to post your current stats (specifically sync rate).

The only thing I can think of would be banding, which was removed with the switch to BT, and since reapplied after changing ISP again. Was the drop in sync instant when switching to SSE, or after a few days?

[j0hn]

By DLM profile, it's a setting, there's a choice of Speed, Standard or Stable (those are the Openreach names). It's not easy to reliably find out which one an ISP uses. Not helped by the three options sometimes being called Standard, Stable and Super Stable or something like that by BTWholesale.

According to Kitz page on profiles Standard, Stable and Super Stable are the profiles used for ADSL. I've certainly never seen reference to them in relation to FTTC.

[ejs]

Please refer to https://www.ciz-openreach.co.uk/Consumer/content/118/Generic-Ethernet-Access-over-Fibre-to-the-Cabinet-fact-sheet

[j0hn]

I wasn't disagreeing with you, just stating I hadn't seen those used.
what you just linked me to says exactly what I just said though...

Dynamic Line Management (DLM) features n  Match the way a line is managed to the way your customer uses it:    Standard – best overall balance between  speed and stability for general internet users    Stable – prioritise stability over speed for IPTV videoconferencing, home workers and businesses transferring data and IPTV    Speed – prioritise speed over stability for online gamers.

I see no mention of any other profiles

[ejs]

Perhaps it would have been clearer if you quoted only the part of what I said that you were commenting on. Anyway, the BTWholesale DLM option names are in the WBC FTTC Handbook.

[tommy45]

Hi folks,
Im moving toward bonding several lines from different providers to provide higher throughput and resilience (I am very well versed in the challenges here and have the correct equipment inside of each ISPs network already). I had some ISPs in mind, due to that fact. so thought id give a newbie a go as well, as its was only 24 a month including the line rental for 80/20.

As Kitizens may remember, I was with Plusnet and then later with BT infinity. As noted in my post at the time, I noticed the physical line sync speed went up some 10% (or there abouts) when we went from Plusnet to BT - with plusnet it was a solid 69 sync (since the pair swap) and then the day we migrated to BT it went to high 78+. That was about 14 months back.

We have today moved from BT to SSE. The only thing that changed is the provider, no one worked on the pairs.

max sync dropped 10%, back down to 69.

If nothing has changed on my line, but the provider which makes no difference to the copper loop, then why is the sync changing? In a way that appears to favor BT retail

As said it already it could be due in part at least due to the  ISP's different  default choice's of the DLM stability option,And the Error rate of the line, The BT openreach Speed option has the higher threshold of the 3 options available, Plusnet are known to choose this option , bt retail may as well, There again the reduction in sync maybe a fault or cross talk

[roswellgrey]

Can you deduce the DLM stability option from the Interleve Depth ? (i.e. Depth = 1 = Speed) or is it not that simple ?

(I have been wondering about this myself as I saw a similar thing when I migrated ...)

edit ==>

I had a similar observation when I migrated; my situation is more woolly due to a product change on my part, so I am relying on the Attainable as a yardstick.

Was on Infinity 1 (40/10) and was solidy syncing @ 40 Mbps down/9999 Mbps up, with an Attainable of 66 Mbps down / 19 Mbps up.
At migration time to the 80/20 Product (same modem), the Attainable dropped to 58 Mbps down / 19 Mbps up (and syncs at this rate).
As with the OP, the line was not physically touched.
This is obviously a slightly different situation due to my product change, and relying on the modems guess of an Attainable is probably unwise, but I was surprised at this drop....
The modem will have reassessed the Attainable on the new product, but should it change that much ? Who knows ....
Aside from DLM profile change, the only culprit I could think of was INP
Before change : G.INP was enabled (47) & DS Interleve depth was 16
After change  : G.INP is disabled (0) & DS Interleve Depth is 1
So, blame INP - fair enough, but..... when it was enabled in 2015, my Attainable instantly dropped by about 12% - I know it theoretically shouldn't have, but it did .... so I am thinking it is not to blame ...
edit : the above comment wasn't clever .. as my line was syncing at the max rate for the product, Bearer 1 had nowhere to go so it would have reduced  ...

[kitz]

According to Kitz page on profiles Standard, Stable and Super Stable are the profiles used for ADSL. I've certainly never seen reference to them in relation to FTTC.

The profiles for both ADSL and FTTC are on the DLM page under Stability Levels.
Underneath is a list of which ISPs use what profiles.   When I get my PC sorted and have access to the site, I need to add EE under standard.
If memory serves me correctly it was NS that got that info from his ISP.

[kitz]

Can you deduce the DLM stability option from the Interleve Depth ? (i.e. Depth = 1 = Speed) or is it not that simple ?

Unfortunately not.  It either needs confirmation from the ISP.... or the less reliable way which is observation over time of Errored Seconds to see how soon DLM kicks in depending upon the ILQ.

[roswellgrey]

ah well - thought that would be too easy Thanks for the info ...