Kitz Forum
Announcements => News Articles => Topic started by: skyeci on September 30, 2017, 06:34:09 AM
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Mum's service is Bt with 55/10. Woke up the other morning to find resync alert. Ds now at 72 and us at 20. It would appear she has been given a free upgrade for what ever reason. Being within spitting distance from the cab it seems very generous from BT ?? Unless this is a genuine error. Down time during change was around 6 mins.. g.fast pod fitted months ago in case it has anything to do with it..
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Saw this in the BT Broadband area of Thinkbroadband forum from Lee111s
http://bt.custhelp.com/app/answers/detail/a_id/56165/c/346 (http://bt.custhelp.com/app/answers/detail/a_id/56165/c/346)
I wouldn't be too happy if I was on Infinity 2 or will they all downgrade and then get put back on 80/20 ;D. Seems an odd thing to do if it benefits customers who are paying less ???.
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Thanks for the link.. Seems very fortunate for once.
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ISPReview also now have an article https://www.ispreview.co.uk/index.php/2017/09/uk-isp-bt-start-free-fttc-infinity-1-broadband-speed-boost-76mbps.html (https://www.ispreview.co.uk/index.php/2017/09/uk-isp-bt-start-free-fttc-infinity-1-broadband-speed-boost-76mbps.html)
Ian
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I can see some being for happy with this, my brother included. But there will be a lot of annoyed Infinity 2 uses who are paying more, and what about people on FTTP, will they be upgraded to 80/20?
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I wonder why BT decided to do this.
I wonder if its an attempt to narrow the speed gap between those who will get G.fast and those not.
I'm one of the infinity 2 people and I'm not happy. They should reduce the price of Infinity 2 to Infinity 1 prices.
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It may well lower the average speed on infinity 1, but could make the average speed on infinity 2 higher so it could all be down to advertising.
If people see that Infinity 2 has a higher average speed then more people may well choose to go with that package.
Of course BT could just be choosing to be nice to those on infinity 1.
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Hi ronski
I hope you don't mind, but you've lost me on lowering infinity 1 speed average and increasing infinity 2 average speed
As bt are upgrading infinity 1 speed to same as infinity 2 speed 80/20, they must have capacity to maintain those speeds. If not, then it's wrong
I'm on infinity 2, bemused as I've just entered a 24 month contract at a lot more cost then infinity 1.
To be honest, even if they upgrade the infinity 2 speed, it does not matter as it would not speed things up viewing websites.
I guess we will have to wait and see
Many thanks
John
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My neighbour was on 55/10 too. Just looked at his smart hub. Now 62/20..
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These are the regular GEA FTTC annual (ex VAT) prices
Up to 40Mbit/s downstream and up to 2Mbit/s upstream (including Simultaneous Provide) 01/07/2009 82.80
Up to 40Mbit/s downstream and up to 10Mbit/s upstream (including Simultaneous Provide) 01/09/2011 88.80
Up to 55Mbit/s downstream and up to 10Mbit/s upstream (including Simultaneous Provide) 16/01/2016 100.80
Up to 80Mbit/s downstream and up to 20Mbit/s upstream (including Simultaneous Provide) 10/04/2012 119.40
Openreach have a couple of special offers on atm
- Bandwidth modify (https://www.openreach.co.uk/orpg/home/products/pricing/loadProductPriceDetails.do?data=5uW5cDedIGJkun%2FLo2I67MvbL9LIX%2BdbrR7CHm%2F5%2FpCrmMllOOG7b%2F12AmPFLBERe6YShZ82RgLOGLsH2e9%2Bmw%3D%3D) GEA-FTTC lines upgrading to a higher speed tier.
£10 - Free until 30/11/2017
- Then there's this (https://www.openreach.co.uk/orpg/home/products/pricing/loadProductPriceDetails.do?data=4VdwBlqxgc%2B%2BjgL5wNoS7j%2FsrnjJlv3x6mwsUd7QNGyrmMllOOG7b%2F12AmPFLBERe6YShZ82RgLOGLsH2e9%2Bmw%3D%3D) - Volume commitment to 80/20
GEA-FTTC 80/20Mbit/s with eligible SIM provide
Tier 1 - £95.40
Tier 2 - £109.44
Slow Lines regraded to GEA FTTC (ADSL lines <10Mbps)
Tier 1 - £95.40
Tier 2 - £109.44
This makes me think that 'an ISP' could do a marketing push saying something similar to 'All lines provisioned at 80/20 which no other ISP does therefore making us the fastest ISP with better upload speeds blah blah' Could be used to encourage adsl users to upgrade to vdsl.
I've no doubt that BTretail will have done the maths and if they think a marketing campaign used in this way could bring in a lot of new customers. They won't be the first ISP to provision all lines on 80/20 - except Plusnet speed capped in-house. Perhaps I am just being cynical, but I do think there will be some underlying reason why they are doing this, and marketing seems the most obvious.
* Tier 1 prices are available if the CP delivers a 50% uplift in baseline volumes on the relevant product (to 80/20 in this case)
Tier 1 prices are available if the CP delivers a 25% uplift in baseline volumes on the relevant product (to 80/20 in this case)
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Will this potentially increase cross talk values if more lines are at a higher sync on cabs that were at lower syncs previsouly.thinking non g.inp ECI users with high es etc etc..
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Dlm is now increasing sync again after upgrading from 55/10 to 80/20. Just dropped snr to 5.4 so it's at 76/20.seems to good to be true.
55/10 >72/20>76/20 (5.4 on ds)
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Those Openreach special offer annual rental prices are only for lines switching from ADSL, or for new/stopped lines getting FTTC. I think those Openreach special offers are to encourage more people to get FTTC at any speed tier, I don't think an ISP would get them for switching a large proportion of their lower speed FTTC users to 80/20.
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Hi ronski
I hope you don't mind, but you've lost me on lowering infinity 1 speed average and increasing infinity 2 average speed
As bt are upgrading infinity 1 speed to same as infinity 2 speed 80/20, they must have capacity to maintain those speeds. If not, then it's wrong
I'm on infinity 2, bemused as I've just entered a 24 month contract at a lot more cost then infinity 1.
To be honest, even if they upgrade the infinity 2 speed, it does not matter as it would not speed things up viewing websites.
I guess we will have to wait and see
Many thanks
John
It says only if your line can support it. As we know a line will only support what it's capable of. So any line that is on Infinity 1 and syncing at 55/10 will almost certainly have the ability to sync higher, BT may well know the attainable, so it can choose which lines will be upgraded, it may well pick lines that can sync much higher than 55. Now as we know a lot of people choose Infinity 1 for price, so a lot of Infinity 1 lines might well be capable of syncing much nearer to 80/20. Potentially pushing up the average speed for Infinity 2. My brothers line with xDB may well reach the mid 70's, possibly even the max.
Meanwhile if you've removed the fastest lines from Infinity 1 it will no doubt lower the average sync speed.
Only way they could potentially upgrade Infinity 2 speeds is if Openreach released a faster VDSL product, which I doubt very much will happen.
Hope that makes sense
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Meanwhile if you've removed the fastest lines from Infinity 1 it will no doubt lower the average sync speed.
Where does it say they're removing lines from Infinity 1?
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If you upgrade some from one product to another f.o.c, those on lesser products effectively are being charged relatively more for theirs. The likes of PN with its 40/2 40/10 could become less attractive. Could there be reason to think that BT have in view the consolidation in to one single brand. Reports of Plusnet services standards seem to indicate indifference.
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Hi
@romski - many thanks, I understand now what you were you saying
@dray - bt are not removing any lines from infinity 1, but those that are been upgraded to infinity 2, will no longer been shown as infinity 1 lines
I think its a bad move on the part of bt retail - probably why it's not been widely publicised - might even look at the EE offer for 100GB data and iPhone - drop all bt lines and services and save overall (when you calculate line rental, broadband charges and mobile costs together), and could setup own personal VPN with our systems in the datacentre hmmm
Many thanks
John
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@dray - bt are not removing any lines from infinity 1, but those that are been upgraded to infinity 2, will no longer been shown as infinity 1 lines
No one is being upgraded to Infinity 2
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It says only if your line can support it. As we know a line will only support what it's capable of. So any line that is on Infinity 1 and syncing at 55/10 will almost certainly have the ability to sync higher, BT may well know the attainable, so it can choose which lines will be upgraded, it may well pick lines that can sync much higher than 55. Now as we know a lot of people choose Infinity 1 for price, so a lot of Infinity 1 lines might well be capable of syncing much nearer to 80/20. Potentially pushing up the average speed for Infinity 2. My brothers line with xDB may well reach the mid 70's, possibly even the max.
I thought the lines will still be under Infinity 1, just operating at 80/20. The upgraded lines will still be Infinity 1.
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A rose by any other name............... :)
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Good point @Dray & @EJS, so surely that's going to confuse the average speeds on Infinity 1 when some customers are getting Infinity 2 like speeds.
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They might be still considered Infinity 1. But in reality they are getting the Infinity 2 service, yet paying a lesser price.
I'm hoping that we're only seeing half the update. Because if they leave it like this there is going to be a lot of annoyed people, especially those under contract paying Infinity 2 prices for 12 months or more.
BTW, I'm happy for you guys on Infinity 1 getting the speeds your line deserves. I just hope they talk about dropping the price for Infinity 2.
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They might be still considered Infinity 1. But in reality they are getting the Infinity 2 service, yet paying a lesser price.
I'm hoping that we're only seeing half the update. Because if they leave it like this there is going to be a lot of annoyed people, especially those under contract paying Infinity 2 prices for 12 months or more.
BTW, I'm happy for you guys on Infinity 1 getting the speeds your line deserves. I just hope they talk about dropping the price for Infinity 2.
We who are on Infinity 2 will get upgraded to G.Fast... :lol:
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Seems its to push up the mean speeds by upgrading those with high attainable.
Unsurprisingly existing infinity 2 users arent happy as they paying more now for same speed.
Wonder what would happen if I rang saying, I will accept free service in return for pushing up their figures. :)
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From Thinkbroadband news comments -
(https://s25.postimg.org/yt3q4t6v3/100mbit_BT.jpg)
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hmmm I doubt that. It would be Openreach that needs to decide that not BTr. I hardly think Openreach would increase the max sync to 100Mbps - especially not whilst we still have the g.inp and vectoring mess. :-\
Off the top of my head I think countries that offer 100Mbps on VDSL2 tend to use vectoring, because I don't see too many lines these days which could support 100Mbps now that cross-talk has been eating away at massive chunks of speed.
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I doubt he's referring to VDSL, sounds more like G.fast - I think 100Mb would encompass a lot of premises. The figure of 100Mb I think would also work well, psychologically, in advertising - sounds like a "barrier" being broken to the average consumer.
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I thought 100Mbps was the minimum speed you need to be able to get for them to let you have G.fast.
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I thought G.Fast was 160Mbps
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150mbps mimimum I was told by my last OR engineer who said he had just been on a g.fast training course...
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I stand corrected. :)
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One of the G.fast offerings will have maximum speeds of 160/30, so a minimum of 150 seems unlikely.
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I've not got a G.fast pod on my cabinet :(
Also a question, if more people are now sync'ing at higher speeds, does this increase crosstalk?
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Both my parents line and my brother have BT Infinity 1 atm - checking with him today, he got the 'boost' email on Friday and is close enough to the cabinet that I think he should get the full 80/20 but won't notice it
I guess I should get around to fixing (http://forum.kitz.co.uk/index.php/topic,19560.msg344875.html) my parents line as that should normally sync at 55/10 (no email received by them yet) and is about 52/10 atm.
They both also have g.fast pods attached to their cabinets.
Ironically, I'm due to move to Sheffield for the next few months - just around the corner from Plusnet's HQ actually - and can you get FTTC or cable there.. no >:( (despite it being a heavy student/professional area)
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Also a question, if more people are now sync'ing at higher speeds, does this increase crosstalk?
Where the extra speed comes from carrying bits on tones that were silent, then yes. Where it comes from carrying more bits on tones that were used before, then no.
I believe that the latter case is much more likely than the former, so the overall answer is: no, not much.
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Line now at 79088 on the ds..
Wish I had mum's line...so jeaulos right now lol
55/10 76/20 79/20 whilst paying bt infinity 1. Dlm has dropped snr to 4.5 (huawei)
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Also a question, if more people are now sync'ing at higher speeds, does this increase crosstalk?
That would depend on if the transmitted power is reduced when the speed is capped, I don't think this is being done.
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That would depend on if the transmitted power is reduced when the speed is capped, I don't think this is being done.
If some lines were being held to a reduced power (on an individual tone), wouldn't that make them into a crosstalk victim?
If the whole point of the DPBO process is to minimise crosstalk into/from ADSL lines, and to balance the power between the two systems, then it follows that every VDSL2 line has to transmit at the same power level too. At least logically.
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That would depend on if the transmitted power is reduced when the speed is capped, I don't think this is being done.
I agree, seems unlikely based on what I have seen.
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Where the extra speed comes from carrying bits on tones that were silent, then yes. Where it comes from carrying more bits on tones that were used before, then no.
I believe that the latter case is much more likely than the former, so the overall answer is: no, not much.
DSL uses the water fill method to load bits into tones. Therefore the latter case should be true.
If more people are now sync'ing at higher speeds, does this increase crosstalk?
Missed this earlier - In theory, No it won't cause additional crosstalk because no new tones are available on the line. The only time more tones are made available is upon a change of technology ie adsl, adsl2, vdsl1, vdsl2.
One of the reasons we see more crosstalk when neighbouring lines upgrade to FTTC is previously they will have only been using the frequencies up to 2.2 MHz. When they get vdsl2 they now get up to ~4000 bins to play with. The waterfill method ensures that a line should always make use of the highest tone it can even if the SNR on that tone is only sufficient to load 1 bit.
If you give a line more speed to play with by removing the 40/55 limit then it will just fill up existing tones. For those lines which are capable of achieving higher speeds, the 40/55 is in effect an artificial cap which halts the water fill process once sufficient bits are loaded to reach 40/55Mbps. Remove the cap and it just keeps filling until it either reaches 80Mbps or its natural limit for the line.
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ETA
The limits set at the DSLAM aren't the same as any capping done by the ISP. If a line is set as 80/20 at the DSLAM, the line will still sync as high as it can. The ISP caps by restricting the maximum throughput speed.
Any banding by DLM is done at the DSLAM and affects bitload.
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I agree about the water-filling having the effect of spreading bits over every feasible tone. The one technicality that I wonder about is when power backoff is in play - whether it works in opposition to water-filling sometimes.
In the downstream case, I don't think we see this kind of opposition. The power is reduced by a fixed amount for all lines, which then has a fixed impact to the SNR values, and so a fixed impact as to whether a tone is "feasible" or not. Water-filling will still use as many tones as it can; it just doesn't get many bits in the affected tones.
In the upstream case, I'm less sure. The power reduction isn't fixed, so it is plausible that, sometimes, a power setting for a nearby subscriber causes it to use the U2 band in preference to U1 ... whereas higher power could allow U1 to be used. I'm unsure as to whether the dynamic system works in a way that accounts for the desired capacity. For example, would a 10Mbps subscriber would end up using lower power than a 20Mbps subscriber, simply because the extra power would end up merely giving superfluous excess SNRM?
(If it isn't obvious what I mean, consider a "water-filling" algorithm that starts with the lowest power on every tone, and then starts to water-fill by gradually turning up the power across all tones until enough bits have been allocated.)
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What else is there to complain about?
How about:
Will all these Infinity 1 customers with more bandwidth lead to peak-time congestion?
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He he he ..... ^^^ ;D
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What else is there to complain about?
Three little letters.................E....................C..................I :yuck:
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:lol: - classic
Three little letters.................E....................C..................I :yuck:
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Aye downstream shouldn't be an issue. I'm not 100% certain about upstream because of PBO. We certainly do see different patterns of bit load in U1.
I could be wrong, but I just assumed this was something to do with line length in a similar way that differing spectral masks are used for some of the tones in D1 shared with adsl which are based on cab location from exchange. From memory theres several (5?) different masks in use based on line length from cab.
If so then neighbouring lines of similar length should have little impact because they should have a similar [upstream] PSD mask.
I suppose there could be more room for variance if your line in the bundle is getting crosstalk from a line of different length. Not sure what the odds of that are, but I assume that this is what you are thinking of in your example? Either that or Im not quite sure what you mean about turning up the power :/
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For some reason the D3 band has become active and showing a signal attenuation and SNR margin as seen below
xdslctl info --pbParams
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 5960 Kbps, Downstream rate = 43570 Kbps
Bearer: 0, Upstream rate = 5960 Kbps, Downstream rate = 40000 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)
Medley Phase (Final) Band Plan
US: (7,32) (871,1205)
DS: (33,859) (1216,1961) (2793,3603)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 5960 kbps 43570 kbps
Actual Aggregate Tx Power: - 0.1 dBm 11.6 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 8.7 43.0 N/A N/A N/A 20.0 52.7 81.6
Signal Attenuation(dB): 8.7 42.5 N/A N/A N/A 22.3 52.4 100.3
SNR Margin(dB): 6.0 6.0 N/A N/A N/A 3.6 3.7 3.8
TX Power(dBm): -11.2 -0.4 N/A N/A N/A 8.6 7.8 0.5
>
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'Infinity 1' -> 80Mb Openreach product.
'Infinity 2' -> 160Mb Openreach product.
BT Retail move money to Openreach via BT Wholesale, provide an anchor tenant for G.fast and force Sky, TalkTalk and Vodafone's hand in either getting on board with NGA 2 quickly, investing in FTTP either with Openreach or A N Other, or explaining why they aren't to their subscribers.
Maybe.
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'Infinity 1' -> 80Mb Openreach product.
'Infinity 2' -> 160Mb Openreach product.
If they did that it would be interesting how many people would downgrade to Infinity 1.
I'd also be interested in seeing how many lines currently can even sync at the full 80Mb.
Also I wonder what the legal standing is if they contracted someone to a 12 month contract paying infinity 2 prices just before this Infinity 1 speed boost? I wonder if there would be a case for deceptive sales practices? I know they tried to re-contract with me when I contacted them after the power cut purely to get this SH6 (which was over priced by them.. I ended up picking up a SH6 for £50 cheaper at curry's pc world). If they had contracted me at that time, and then this price shuffle, I'd have been as mad as hell (and I'm not gonna take it anymore :rant: ) :)
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I just cannot see BT doing that, that's throwing money down the drain as a masse of people will downgrade to infinity 1.
Yes its how virgin media operate, but virgin media are strange in that respect.
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Mum's line has now achieved full speed less than a week from the free upgrade after dlm has been stepping down the snr. Now at 79999/20 with ds snr at 4.1 on huawei cab.
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I just cannot see BT doing that, that's throwing money down the drain as a masse of people will downgrade to infinity 1.
Yes its how virgin media operate, but virgin media are strange in that respect.
Not really. BT are strange in that respect in that they don't follow that example. Competition should be about more than just price and what tat you can chuck in with the connection.
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I could be wrong, but I just assumed this was something to do with line length
The basic design for UPBO seems to depend on a parameter known as a "reference length", which can be set differently per band. And I think it does include the estimate of the electrical length of the line (ie attenuation). And the outcome certainly looks like it lowers the PSD mask. All knowledge taken from my favourite white paper on UPBO: #5 on this website (http://4gbb.eu/index.php/publications/white-papers). So it looks like length is involved a lot.
For my line, it looks like they've set things to really dissuade it from using U1: SNR-per-tone is 10dB lower in U1, even though QLN noise is 10dB better. I guess power must be lower in U1 by 20dB.
All good so far, so long as that estimate of electrical length doesn't change. In these circumstances, UPBO looks like it should be static.
However, I have seen times when the transmit power (per band, visible in "pbParams" output) has changed after a resync. No idea why; perhaps the length estimate went wrong on that sync, perhaps something else was detected. I just leave a marker in my head that things aren't necessarily static, and that I don't know enough...
From memory theres several (5?) different masks in use based on line length from cab.
The ANFP has a graph that shows 6 different downstream PSDs, based on 6 different CAL values. However, it is stated in text that CAL can actually vary from 0dB to 52dB in steps of 2dB, so the graph is really only a depiction of a few examples. There are really 27 different masks.
If so then neighbouring lines of similar length should have little impact because they should have a similar [upstream] PSD mask.
I suppose there could be more room for variance if your line in the bundle is getting crosstalk from a line of different length.
A line is likely to share a little of the path in a cable bundle with lines of similar length. At least the distance from, say, the street chamber to the DP at the top of a pole. But the rest of the route back to the cab is going to be shared with a variety of lengths ... I guess the likelihood of crosstalk here from disparate lengths depends on how organised BT are about how they subdivide larger bundles at each pole/DP.
However, I suspect a fair proportion of crosstalk is sourced from the tie pairs, where your immediate neighbouring pairs could be any length.
Either that or Im not quite sure what you mean about turning up the power :/
The "turning up the power" part is an alternative way of thinking about water-filling.
In the traditional way, you start with fixed power, and fixed SNR per tone. You then iteratively ask: has this tone got an extra 3dB of available SNR? If so, give it an extra bit. Until you reach package speed, or run out of SNR.
In this alternative way, you start with minimum power, and no SNR. You then iteratively ask: can we turn the power of this tone up by 3dB? If so, increase the power and then ask if it has 3dB of available SNR? If so, give it an extra bit. Until you reach package speed, or run out of power increments.
In the latter way, you end up transmitting at lower power - in fact, just enough power to achieve the desired 6dB margin. And you wouldn't transmit on any tones where this lower power level wasn't enough to raise SNR above the margin.
This is just a thought game though - a potential way to make UPBO dynamic, and account for some of the times I have seen a change. I've seen no evidence that such a mechanism exists.
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I'd also be interested in seeing how many lines currently can even sync at the full 80Mb.
Here's one I made earlier ;)
This is Ofcom's graph of VDSL2 speed distribution in 2014, before the 55/10 package became available. I overlaid it with an estimate of what it might look if every line was on an 80Mbps package, using fairly straightforward extrapolation (ie guesswork).
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Not really. BT are strange in that respect in that they don't follow that example. Competition should be about more than just price and what tat you can chuck in with the connection.
Consider that g.fast isnt the same coverage as vdsl2, so what does this achieve in areas with no g.fast but do have vdsl2?
Maybe you right, but makes little sense to me. :)
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Consider that g.fast isnt the same coverage as vdsl2, so what does this achieve in areas with no g.fast but do have vdsl2?
Maybe you right, but makes little sense to me. :)
How about:
VDSL gets BT Infinity 1
g.Fast gets BT Infinity 2, BT Infinity 3 and BT Infinity 4
FTTP gets BT Infinity 3 and BT Infinity 4
Customers who downgrade from Infinity 2 to Infinity 1 sign a new 2-year contract.
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All knowledge taken from my favourite white paper on UPBO: #5 on this website (http://4gbb.eu/index.php/publications/white-papers).
Aha!
I was just re-reading that UPBO document a little further, into the section on "Specifying UPBO Via Access Rules".
That section suggests that the best way to set access rules (ie in the ANFP) is by specifying spectral limits rather than explicit modem settings. ie by PSD masks. It further says that the UK & Dutch rules are set using PSD masks, and then explains that the UK rules are based on line length from the cabinet.
I guess we have our answer: UPBO works by setting spectral limits, based on line length.
So I went back to the ANFP, to find there is a "Part C" that describes the PSD mask for CPE placed at the NTE. Within a single graph, it seems to include PSD restrictions that apply simultaneously for exchange-based ADSL (with 5 named configurations, dependent on line length: "ushort", "eshort", "short", "medium", "long") and for cabinet-based VDSL2 (with variations based on "kl0").
The named configurations, for exchange-based ADSL, are specified by the ANFP as based on insertion loss measured at 100kHz. However, the ANFP doesn't state how kl0 is measured.
According to NICC test document ND1436 (for VDSL2 modems), kl0 is the attenuation/insert-loss measured at 1 MHz. kl0=2 is equivalent to 100m of TP100 cable, kl0=10 is equivalent to 500m of TP100 cable.
According to SIN 498, TP-100 cable is twisted pair cable with 100 ohm impedance, and is 0.5mm copper.
The ANFP Part C suggests that the upstream PSD mask varies for kl0 values between 0 and 24, suggesting that UPBO has an effect for cables up to 1.2km.
I've attached the graph from the ANFP. From the example kl0 values used, it looks like U1 varies for kl0 between 0 and 24 (ie 0 and 1200m), whereas U2 only varies for kl0 between 0 and 8 (ie 0 and 400m).
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How about:
VDSL gets BT Infinity 1
g.Fast gets BT Infinity 2, BT Infinity 3 and BT Infinity 4
FTTP gets BT Infinity 3 and BT Infinity 4
Customers who downgrade from Infinity 2 to Infinity 1 sign a new 2-year contract.
Given VDSL will remain the mainstream product its odd that has 3 products and vdsl2 just one. I await to see what happens. :)
I suppose this theory works on the basis that there is already a bt infinity 3 which is above g.fast spec, so they need to slot in g.fast somewhere.
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Of course,
VDSL gets BT Infinity 1
g.Fast gets BT Infinity 2, BT Infinity 3 and BT Infinity 4
FTTP gets BT Infinity 1, BT Infinity 2, BT Infinity 3 and BT Infinity 4
looks more elegant
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Maybe.
So it is just your speculation or the result of imbibing a certain neck embrocation? ;)
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Of course,
VDSL gets BT Infinity 1
g.Fast gets BT Infinity 2, BT Infinity 3 and BT Infinity 4
FTTP gets BT Infinity 1, BT Infinity 2, BT Infinity 3 and BT Infinity 4
looks more elegant
I thought that there were only 2 g.fast speed tiers?
If so, that would be:
VDSL gets BT Infinity 1 and lets not forget about Unlimited Faster Broadband
g.Fast gets BT Infinity 2 and BT Infinity 3
FTTP gets BT Infinity 1, BT Infinity 2 and BT Infinity 3
On a more serious note, BT have been saying for several years that they want to differentiate BT Broadband on service and quality rather than cost (for which they have Plusnet) - and its not the first time that BT Retail have upgraded the speed of their customers.
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I've just spotted a comment on ISP Review dated 1 September, which seems to make a lot of sense why they'd change Infinity 2 to G.Fast
https://www.ispreview.co.uk/index.php/2017/09/330mbps-g-fast-pods-appearing-broadband-delivery-uk-areas.html#comment-181122
OK it's only someone's opinion but it does make sense from a marketing perspective.
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I guess there's a temporary limit as to how much they want to promote G.Fast too - with the pods only capable of supporting 48 subscribers instead of the ultimate 96.
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That section suggests that the best way to set access rules (ie in the ANFP) is by specifying spectral limits rather than explicit modem settings. ie by PSD masks. It further says that the UK & Dutch rules are set using PSD masks, and then explains that the UK rules are based on line length from the cabinet.
So I went back to the ANFP, to find there is a "Part C" that describes the PSD mask for CPE placed at the NTE. Within a single graph, it seems to include PSD restrictions that apply simultaneously for exchange-based ADSL (with 5 named configurations, dependent on line length: "ushort", "eshort", "short", "medium", "long") and for cabinet-based VDSL2 (with variations based on "kl0").
Ahhh thank you for that - So I was on the right track & my memory wasnt that bad then when I said.
I could be wrong, but I just assumed this was something to do with line length in a similar way that differing spectral masks are used for some of the tones in D1 shared with adsl which are based on cab location from exchange. From memory theres several (5?) different masks in use based on line length from cab.
If so then neighbouring lines of similar length should have little impact because they should have a similar [upstream] PSD mask.
Its just that there are more available U1 masks than there are for D1. Perhaps I could have worded it better, but if you re-read, you can see I was aware of the 5 D1 masks based on cab location, and was assuming that another (5?) applied for UPBO based on loop line length between the cab and NTE.
The ANFP Part C suggests that the upstream PSD mask varies for kl0 values between 0 and 24, suggesting that UPBO has an effect for cables up to 1.2km.
Nice find... and even better detective work on putting together some kl0 values. :thumbs:
I'm trying to put together all that info along with that in the white paper.
So in summary have I got this right
- D1 has 5 available PSD masks based on cab location from the exchange.
- U1 has 10 available PSD masks up to 1200m based on line length
(The white paper gives an example for 7 different lengths up to 1500m). - U2 has 4 or is that 5 available PSD masks up to 400m based on line length.
[edited in an attempt to clarify]
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PS
I also noticed this in section 3 of the white paper
UPBO is only meaningful for upstream frequencies that are strictly separated from downstream frequencies, in
combination with topologies where nearby and distant customers served via the same cable are very different in
distance [7].
I guess that then covers my earlier doubts about any differing lengths perhaps occurring in the same bundle. What's your take on the tie pair at the cab?
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Yes, it does come back to you being right about how it works. I'm happy to think I've got a good handle on how UPBO gets configured now.
However, I still think there are ~25 masks downstream, and an infinite number upstream. More than are shown in the graphs, at any rate.
Let me think about your questions & get back later...
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I just tried putting the ANFP upstream formulae into a spreadsheet, to come up with my own example graphs. Here are a few, which I think shows that the graphs can vary as much as kl0 can vary.
If kl0 is restricted to integers, then there are 25 masks. If kl0 can hold any real value, then the number of possible graphs goes up.
Here are some examples...
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This graph shows that the mask in U1 maxs out around kl0=23.5.
My conclusion is that the ANFP really specifies modem behaviour in the formulae in the table; the graphs are just a few examples made using those formulae.
For upstream, I don't (yet) know how many decimal places kl0 can be calculated to (the formulae in the table runs to 5 significant figures). But we do know that the table copes as it varies between 0 and (just under) 24.
Individually, and slightly more accurately, it looks like U1 changes as kl0 varies over a range of 0-23.6, whereas u2 changes as kl0 varies over a range of 0-8.5.
For downstream, we know that CAL can vary from 0 to 52, but only in integer steps of 2, so we know there are exactly 27 graphs there.
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PS
I also noticed this in section 3 of the white paper
UPBO is only meaningful for upstream frequencies that are strictly separated from downstream frequencies, in
combination with topologies where nearby and distant customers served via the same cable are very different in
distance [7].
I guess that then covers my earlier doubts about any differing lengths perhaps occurring in the same bundle. What's your take on the tie pair at the cab?
The first restriction seems strange. Surely VDSL2 only works where upstream and downstream bands are separated anyway, never mind the UPBO tweaks? However, if you did allow overlap, then the ensuing NEXT would be made even worse if you tried to reduce upstream power via UPBO.
The second part is a condition that we obviously meet through the tie pair, if no other part.
I tend to think that most crosstalk happens where power is the highest, and so the electrical field is at its greatest. That would mean FEXT is induced most at the DSLAM (and thus in the tie pairs), and least in the drop wires.
It also means that you'd expect less crosstalk where the tie pairs are shortest.
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For downstream, we know that CAL can vary from 0 to 52, but only in integer steps of 2, so we know there are exactly 27 graphs there.
I don't think what it says in the ANFP document means that those are the only values of CAL.
The range and precision of kl0 is defined in ITU-T G.997.1, "The value ranges from 0 to 128 dB in steps of 0.1 dB".
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I don't think what it says in the ANFP document means that those are the only values of CAL.
So there could be more than that? By being outside the range 0-52, or by taking values that aren't in 2dB steps?
For a normative section, part B of the ANFP is pretty vague about the range. It clearly mentions the 0-52dB in 2dB steps, but it only actually specifies that range as important for the "critical intersection points" on the graphs, not as a definitive statement of the complete range.
The range and precision of kl0 is defined in ITU-T G.997.1, "The value ranges from 0 to 128 dB in steps of 0.1 dB".
Thanks. I guess, then:
- That limits the worthwhile upstream PSD graphs (max 24dB) to be approx 240 in number.
- A maximum of 128dB will be roughly equivalent to 6.4km of 0.5mm copper.
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I guess that then covers my earlier doubts about any differing lengths perhaps occurring in the same bundle. What's your take on the tie pair at the cab?
The first restriction seems strange. Surely VDSL2 only works where upstream and downstream bands are separated anyway, never mind the UPBO tweaks? However, if you did allow overlap, then the ensuing NEXT would be made even worse if you tried to reduce upstream power via UPBO.
The second part is a condition that we obviously meet through the tie pair, if no other part.
I tend to think that most crosstalk happens where power is the highest, and so the electrical field is at its greatest. That would mean FEXT is induced most at the DSLAM (and thus in the tie pairs), and least in the drop wires.
It also means that you'd expect less crosstalk where the tie pairs are shortest.
yep and remember what happened to my line when they reordered my tie pairs. Massive change in crosstalk levels.
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I sync at 54997, will I get this? I won't get much more than that.
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I'm happy to think I've got a good handle on how UPBO gets configured now.
Famous last words, eh?
It seems that UPBO can take two forms, and the one we've been discussing here (and, it appears, that BT uses) is a static model.
There is also a dynamic mode, where the DSLAM can make adjustments to subscribers on the fly. I haven't assimilated the details as yet - there doesn't seem to be much point if BT aren't using it!
Source? There is an interesting document, "Guidelines on the Use of DSL Transmission Systems in the BT Access Network" (http://www.niccstandards.org.uk/publications/guidelines.cfm), ND1405 rev 4.1.1.
As a whole, the document covers how different DSL systems meet (or don't meet) the ANFP. Section 6.11 is for VDSL2, and includes information about DPBO, static UPBO and dynamic UPBO.
yep and remember what happened to my line when they reordered my tie pairs. Massive change in crosstalk levels.
I don't recall that, but it doesn't surprise me.
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Check my saga here.
http://forum.kitz.co.uk/index.php/topic,20191.0.html
Sorry for the delay got distracted after starting the reply.
The short story if you dont want to read the thread is that a car flattened my cab, openreach had to redo all the tie pairs and feed new power, after work was done my stats were much more favourable. 10-30mbit increase on attainable for DS.