Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: TheVoid on April 14, 2018, 09:50:15 AM
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Last year, I was with BT on Infinity 1 and I had the free speed boost. This meant I was getting around 75mbps pretty much all the time.
I then made the mistake of going to Sky in December... I came back to BT in Feb this year on Infinity 1, which I solidly get 52mbps downloads.
Yesterday, I decided to upgrade to Infinity 2. Today the order is complete, but only my upload speed has really changed - it's doubled. My download speed is a little faster at about 54mbps.
Why is it only 2mbps faster when last year I could get 75mbps? I contacted BT and they said I should wait for the line to settle, which I don't believe to be true. The upload speed doubled straight away, but not the download speed.
Any ideas? Here's my line stats, and I have already tried a restart of the hub with no change -
Downstream sync speed:
58.75 Mbps
Upstream sync speed:
20.00 Mbps
Data rate:
20.00 Mbps / 58.75 Mbps
Maximum data rate:
24110 / 60493
Noise margin:
15.3 dB / 6.2 dB
Line attenuation:
14.7 dB
Thanks
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Hi,
Welcome to the forum!
While BT consumer may be known for giving quite typical and canned responses (like many ISPs), in this case they are actually right.
The default SNR (or "noise margin") is 6 dB when on a new provision. In this case it also applies when changing your package as it will reset your Dynamic Line Management (DLM). In order to have achieved 75 Mbps, you were probably on a 3 dB SNR.
There is no set period of time before the DLM sets your line downstream to anything lower than 6 (either 5, 4 or 3 dB). If memory serves me right, anything lower than 6 dB will not be applied unless G.INP is active (I could be wrong, so someone please correct if necessary).
Refrain from rebooting the router too often or making any changes which will make the DLM think you have an unstable line (as this may prevent the DLM from adjusting your parameters). You can learn more about the DLM thresholds here: http://www.kitz.co.uk/adsl/DLM.htm (http://www.kitz.co.uk/adsl/DLM.htm).
I think the best thing you can do is leave it alone and, as long as the DLM sees your line stable, it should eventually get there like it did before.
Just out of interest, what router has BT provided you with when you went back to them? And which router were you using before you switched to Sky?
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I was using a BT Smart Hub the both times.
So is it common for no increase on day 1, but for it to gradually shoot up? The Upload was immediate.
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Your line will go as fast as it can at the default SNR margin of 6 dB after an upgrade, which in this circumstance is about an increase 3 Mbps on the downstream. The only reason why the upstream has doubled immediately is because it has a lot of spare margin to work with (it targets 6 dB, but it can achieve maximum speed at 15 dB in your case).
With some lines when upgrading package, whether that is going from 40 to 55 or 55 to 80 Mbps downstream, there can sometimes be little or no immediate improvement, or even in some cases you can receive less speed at the default SNR margin. This is because when package is changed at wholesale level it triggers a DLM reset. If the person had a lower target SNR (of 5, 4 or 3 dB) prior which meant they were at the top speed for their previous (slower) package then at 6 dB they may receive less unless the DLM intervenes to make positive changes.
So is it common? It's more down to a variety of factors including line length, quality and background noise on the frequencies that VDSL (FTTC) uses. As your line is unable to achieve max speed at 6 dB, there will always be room for improvement until the target SNR is set to 3 dB by the DLM if it determines your line is stable. Based on what you said in your initial post, this will likely happen but there is no time frame for it to happen.
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It might increase when DLM finishes testing it.
I've seen someone on the forums changing between packages and their download speed was stuck on the previous package. It needed a phone call to fix.
I guess for now just watch and wait until DLM does its thing.
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I've seen someone on the forums changing between packages and their download speed was stuck on the previous package. It needed a phone call to fix.
In this case, the sync speed exceeds that of the lower tier package on both the downstream and upstream. So at least in this situation the wholesale product provision has been changed.
Did this other person on the forum have a stuck IP profile or were they still syncing at the lower tier speed? Or was there another factor that I missed?
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I'm not so sure it's as clear cut as that, re0 is assuming your on a Huawei cabinet, if so then given time the speed may increase as it drops the SNR to 3dB presuming the line can support it. If however you're on an ECI cabinet then your stuck at 6dB, although they are supposed to be trialling the lower SNR on ECI cabs.
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@Ronski: That is true. While it is an assumption, it is a faily GOOD assumption since @TheVoid switched from BT to Sky last December (which was only 4 months ago) and was receiving 75 Mbps as they stated. In theory, nothing should have changed significantly since then in regards to crosstalk, especially if it is a cabinet which has been enabled for a long time.
Of course, the assumption can only be good and accurate if the information provided is also accurate. But there is a good chance that with G.INP + 3 dB profile the line should be able to support quite near those speeds.
@TheVoid: Perhaps you could confirm which type of cabinet you are on (Huawei or ECI)? If you don't have an unlocked router to hand, you may need to go out and take a look at your cabinet and check this (http://www.kitz.co.uk/adsl/fttc-cabinets.htm (http://www.kitz.co.uk/adsl/fttc-cabinets.htm)) to confirm.
EDIT:
Sorry that I missed this before. You can find some information here (http://www.kitz.co.uk/adsl/cabinet-lookup.htm (http://www.kitz.co.uk/adsl/cabinet-lookup.htm)) on how to look up your cabinet information. More specifically without an unlocked router, you can use CodeLook (https://www.telecom-tariffs.co.uk/codelook.htm (https://www.telecom-tariffs.co.uk/codelook.htm)) and look up the information in your locality to find the vendor used in your cabinet. If you are not sure which cabinet you are on, you can use your number on the DSL Checker (https://www.btwholesale.com/includes/adsl/main.html (https://www.btwholesale.com/includes/adsl/main.html)) to confirm.
Edit 1: Added another way to lookup the cabinet online.
Edit 2: Corrected sentence.
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You can find your cabinet Vendor without leaving the house by following the guide here...
http://www.kitz.co.uk/adsl/cabinet-lookup.htm
It will will give you exchange and cabinet number. At the bottom of that page it shows you how to find your cabinet on codelook. Codelook will tell you if it's an ECI or Huawei.
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It appears I am on a Huawei cabinet.
Not sure what else to do really apart from wait?
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It appears I am on a Huawei cabinet.
That's good. So it is possible to get 3 dB profile, providing your line is stable enough. It is very possible you had this profile before
Not sure what else to do really apart from wait?
Nothing, really. Just avoid doing things that could disrupt the DLM (such as turning off and rebooting the router too regularly).
I should note that in my case it took approximately a month before G.INP was enabled on my line. There's no telling how long it will take for you, but you won't see your SNR stepping until this is enabled.
Just out of interest, before I forget to ask, what the DSL Checker actually estimate for your line speed (Clean & Impacted for VDSL)?
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Last year, I was with BT on Infinity 1 and I had the free speed boost. This meant I was getting around 75mbps pretty much all the time.
I then made the mistake of going to Sky in December... I came back to BT in Feb this year on Infinity 1, which I solidly get 52mbps downloads.
Yesterday, I decided to upgrade to Infinity 2. Today the order is complete, but only my upload speed has really changed - it's doubled. My download speed is a little faster at about 54mbps.
As others have said, its probably due to the fact that your SNRM target has not yet reduced from 6dB and you have probably lost g.inp during the upgrade process as well.
However, can I ask what http://www.dslchecker.bt.com says for your line?
When I upgraded from Infinity 1 to upto 80MB due to the free speed boost, my download speed actually went down initially
Depending on what the checker says for your line, my advice is if this doesn't improve in 2/3 days, ask BT to arrange a free "boost visit" for your line on the basis that your speeds haven't improved as expected - its worth doing even if the engineer can't improve your speeds much/at all on the day - and you need to wait for DLM/INP to kick in as you're likely to benefit from it then
I did it via the BT forums as they had to manually arrange the speed boost for me as well as well, but they should do it by telephone as well - as an 'early life failure'.
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As others have said, its probably due to the fact that your SNRM target has not yet reduced from 6dB and you have probably lost g.inp during the upgrade process as well.
However, can I ask what http://www.dslchecker.bt.com says for your line?
When I upgraded from Infinity 1 to upto 80MB due to the free speed boost, my download speed actually went down initially
Depending on what the checker says for your line, my advice is if this doesn't improve in 2/3 days, ask BT to arrange a free "boost visit" for your line on the basis that your speeds haven't improved as expected - its worth doing even if the engineer can't improve your speeds much/at all on the day - and you need to wait for DLM/INP to kick in as you're likely to benefit from it then
I did it via the BT forums as they had to manually arrange the speed boost for me as well as well, but they should do it by telephone as well - as an 'early life failure'.
How long did it take for you to get an increase?
So is my line currently being monitored then and will keep improving, or is this just talk by BT?
My stats are:
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fi64.tinypic.com%2F2e4en2v.jpg&hash=a7dfe01833939a3d044e63dc1be5cba3533a8c61)
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So is my line currently being monitored then and will keep improving, or is this just talk by BT?
Your line is always being monitored by the DLM (unless it is disabled, which is not done on FTTC), regardless of your ISP on any xDSL connection. It collects stats from your connection and adjusts the parameters according the to the set stability profile to give you the connection deemed "best" for your line.
It looks like you should be within your estimates once the DLM starts making positive changes.
When you initially had FTTC installed, did an Openreach engineer visit the premises and make any changes to your wiring/fit a new socket? If it not, you might want to check your wiring to ensure you're getting the best speed out of the connection. You can find some information here (http://www.kitz.co.uk/adsl/socket.htm (http://www.kitz.co.uk/adsl/socket.htm)) regarding how to improve broadband speed (ignore it just being listed for ADSL, since this still applies to VDSL).
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How long did it take for you to get an increase?
My line was upgraded on 12/2/18. Within 2 weeks g.inp came back (though this period varies per line) and DLM started reducing in 1dB stages on 4 March. I had the boost visit after g.inp had come back but before the SNRM started reducing. I posted some of the history at the time here (http://forum.kitz.co.uk/index.php/topic,21102.0.html) and now get 69MB
So is my line currently being monitored then and will keep improving, or is this just talk by BT?
All the lines are continuously monitored by Openreach's DLM system and things will improve as you have a Huawei cabinet. If you had an ECI one, things wouldn't be so positive.
If you want to see if BT will agree to a boost visit it has to be requested within 28 days I believe.
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By way of a short story ..... I did a repair on a local VDSL circuit on Friday morning. They were running at 27Mbps with a crackly phone line.
Fix completed and I performed a full DLM reset ..... their router came back into synch at 47Mbps. I had a slight niggle that they were closer to the Cab for that speed, and so decided to check again via a remote test, yesterday. They were now in synch at 76Mbps !!!
Have you ever seen those cartoons where their eyes go like saucers and nearly pop out of their head !! :o ;D ;D
So, maybe things will improve for your circuit in time ??
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Just did another speed test and it's shot up to 60mbps! I guess it's going to take time to get to the highest level.
Looking at those stats above, it looks like my line can go up to 80mbps though right?
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Here's a photo of my master socket. It was like this when we moved in 3 years ago. Looks a bit bulky to me! Ignore the black box below it, it's my mobile phone signal booster.
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fi65.tinypic.com%2F28web69.jpg&hash=2537aa4d981c278e8a2c8e30c326d9f6283b1546)
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Yes, they're bulky-looking ... but it's exactly the kind of socket I'd want to see on a DSL installation.
We have moved to a MK4 SSFP now, but believe me, the MK3 you have is more than adequate.
Others may be able to answer your question around your stats, and further speed increases ??
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Just did another speed test and it's shot up to 60mbps!
I would say that a one-off speedtest is probably not the best way to gauge any improvement since there are so many factors that can impact the reliability of a speedtest (such as computer specifications, other users on the network and even the web browser in use). In this case, we should stick to monitoring the sync speed and statistics from the router directly.
I guess it's going to take time to get to the highest level.
There is no real time frame that can be applied to how long it will take for your connection to reach its potential. It depends on the DLM and whether your line is within the defined thresholds for improvement. Since SRA (Seamless Rate Adaption) is not used on xDSL products that are on Openreach's network, it's not exactly a smooth transition upwards towards 80 Mbps but rather the link (connection between your router and the hardware in the cabinet) will be dropped (usually early hours in the morning) and the connection speed will be renegotiated with the defined parameters from the DLM if any changes are due.
Looking at those stats above, it looks like my line can go up to 80mbps though right?
Please bear in mind that the quoted 80 Mbps on the DSL Checker refers to SYNCHRONISATION SPEED as opposed to ACTUAL THROUGHPUT on the network. Actual throughput while synchronised at the full 80 Mbps under good coniditions will be around 75 Mbps as there will be a small overhead.
The key words used here are "up to". It depends on so many different conditions. So you may be able to synchronise at 80 Mbps one day, and after a rescync maybe 76 or 77 Mbps. Seeing as you have stated you have received 75 Mbps in the past, if you were referring to actual throughput (through downloads and speedtests) then there was a good chance that you were synchronised at or near 80 Mbps.
Edited to clarify some information.
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Well my line stats seem to have improved which would explain the jump to 60mbps, however frequent speed tests are still saying an average of 49mbps with the occasional result at 60mbps...
Data rate:
20.00 Mbps / 65.36 Mbps
Maximum data rate:
23937 / 66324
Noise margin:
15.3 dB / 6.1 dB
Line attenuation:
14.7 dB
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I can see your data rate has improved by around 7 Mbps. It looks like your SNRM target is still 6 dB, but it is quite difficult to see whether the DLM has made any positive changes to your line thus far since you do not have access to in-depth statistics on the Smarthub. It may be the case that the DLM has adjusted some parameters outside of SNRM (which is the only one we can really obervse on your device); perhaps G.INP has been enabled since that approx. 10% jump in sync and attainable (maximum data rate) seems rather suspect to me unless it is simply caused by variations in conditions throughout the day.
I once read that there was a way to tell whether G.INP had been enabled through the IP profile, but perhaps someone here can confirm or debunk this myth?
60 Mbps throughput would be about right for the synchronisation speed. If you're seeing an average of 49 Mbps then just make sure that you are doing your testing over a wired connection (wireless can support such a speed quite reliably over short distances, but there is always risk of interference and other devices on the network using bandwitdth). Also, you should bear in mind that other factors outside of your control can play a part in the throughput you see such as congested backhaul links that your ISP uses which may - at peak times - see lower speeds.
Out of interest, which speedtest facility are you using?
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Out of interest, which speedtest facility are you using?
I used Speedtest.net
[Moderator edited to remove the unnecessary bulk of the quotation, just leaving the question to which the answer has now been given.]
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Might be worth trying https://www.thinkbroadband.com/speedtest (https://www.thinkbroadband.com/speedtest) as it shows both single- and multi-threaded test results. http://www.dslreports.com/speedtest (http://www.dslreports.com/speedtest) has become another favourite of mine since it seems to be fairly reliable and shows BufferBloat statistics along with ping times to different locations. But if you notice the same variance as with speedtest.net, then perhaps it's because one or more of the issues I have previously highlighted.
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Still only getting 49mbps - 59mbps. Not sure paying £4 a month extra warrents the very slight increase in speed?
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Still only getting 49mbps - 59mbps. Not sure paying £4 a month extra warrents the very slight increase in speed?
In a lot of cases, just the increase in upstream is worth it alone for the extra cost. So, while the increase in downstream may be very slight, if you do a lot of uploading the 20 Mbps will be a big help compared to 10 Mbps (or rather, under good circumstances, ~18 Mbps compared to ~9 Mbps in terms of actual throughput).
As @gt94sss2 said previously in relation to a "boost visit":
If you want to see if BT will agree to a boost visit it has to be requested within 28 days I believe.
As I stated previously, there is no defined period of time before your connection reaches its full potential (since we are essentially waiting for G.INP to be enabled here, which has been known to take many weeks). If you think that you should be receiving more, then perhaps you should follow the advice of @gt94sss2. Otherwise, the best advice is to just sit tight but keep an eye on the stats for improvements.
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Still only getting 49mbps - 59mbps. Not sure paying £4 a month extra warrents the very slight increase in speed?
Speed tests are notoriously unreliable, I have seen consistently low results before on my line while still hitting 76Mbit in real-world usage.
Have you tried http://www.dslreports.com/speedtest as it tends to make the most effort to push the test as hard as possible.
Plus as others have said, you haven't even give the line a chance to stabalise yet. You could yet end up at full sync.
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I think calling a 25-50% increase on download and a 100% one on upload a "very slight" increase is a bit harsh.
In the OP's case, the increase on the downstream is about 13% after upgrading. Thought I can totally agree that 100% uplift on the upstream is not very slight at all.
Speed tests are notoriously unreliable, I have seen consistently low results before on my line while still hitting 76Mbit in real-world usage.
I can agree to a degree. They are only reliable and will show the max throughput if there is sufficient bandwidth from the host and in transit (through backhaul), and/or if the computer is able to reliably run the speedtesting facilities. Speedtests are only good and accurate at measuring throughput if the conditions are right.
Have you tried http://www.dslreports.com/speedtest as it tends to make the most effort to push the test as hard as possible.
I have previously suggested this as I have found it useful for measuring other metrics such as latency and BufferBloat.
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I just find that sites like speedtest.net and thinkbroadband speed test have had issues with my connection, while practically every other real-world website has obtained faster speeds. The speedtest.net app especially seems to be bottlenecked by my phone somehow, as running iperf3 on the same phone can get 300Mbit to a local computer over the WiFi, so it really shouldn't be bottlenecking to the Internet.
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Speedtest.net consistently gives me speed test results that are higher than my actual sync. Seeing as though that is impossible, I don't believe their results any more.
ThinkBroadband's speed test has good routing to most ISP's. Their test gives single thread and multi thread results.
It's never once given me a result higher than what my IP profile is.
It's by far the most accurate/reliable test for myself.
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I just find that sites like speedtest.net and thinkbroadband speed test have had issues with my connection, while practically every other real-world website has obtained faster speeds. The speedtest.net app especially seems to be bottlenecked by my phone somehow, as running iperf3 on the same phone can get 300Mbit to a local computer over the WiFi, so it really shouldn't be bottlenecking to the Internet.
so who is your isp?
speedtest.net is not running great on my phone either, that tells me I have an issue somewhere with the phone's tunable, or its wifi connection or the speedtest app, it doesnt mean the test itself is broken. Might also be an issue with my isp at the time of the test or the speedtest server or the transit link. With that said I rarely run speedtest.net on my PC now as I much prefer tests that use less threads. like speed.of.me and tbb, also dslreports.
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This slipped my mind earlier but, because the your ISP is BT, this page (http://bt.custhelp.com/app/answers/detail/a_id/35296/~/your-line-speed-explained (http://bt.custhelp.com/app/answers/detail/a_id/35296/~/your-line-speed-explained)) should shed some light. While it only counts if the "fault" is reported 90 days of your contract start date, the upgrade will have counted as a new contract.
I did scan through the topic and couldn't immediately find any information in reference to what BT actually estimated and the minimum guarantee that they set for your line (other than the DSL Checker estimates). The best place to find this would in your emails, or perhaps if they have this information on your account portal (I don't know since I am not with BT). Failing that, you could contact them and see what the figures are. Though they probably won't be different from the information on the DSL Checker (unless they the database was updated after you upgraded) since those estimates and the guarantee are based on the Clean high and low range and Downstream Handback Threshold likewise.
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so who is your isp?
speedtest.net is not running great on my phone either, that tells me I have an issue somewhere with the phone's tunable, or its wifi connection or the speedtest app, it doesnt mean the test itself is broken. Might also be an issue with my isp at the time of the test or the speedtest server or the transit link. With that said I rarely run speedtest.net on my PC now as I much prefer tests that use less threads. like speed.of.me and tbb, also dslreports.
I'm with Zen and have been on at least two different variations of their network, I was also on Origin Broadband both on BT backhaul and before that on Digital Region before it closed down. I have always had varied results from those speed tests throughout.
I know sometimes single-thread speeds can be hit by contention but its strange how their multi-thread can do too, with only dslreports being fairly consistent. Pretty sure its not the router either as I have been through various over the years and as I have been running pfSense on an Atom for some years now there is plenty of spare overhead, plus real-world performance is never a problem. We regularly have three of us watching Netflix at the same time with one of them in 4K without any issues.
Anyway the point is, an artificial speed test can only be a guideline. You have to monitor real-world performance as well to get a clear picture. The BT/Openreach speed tests in particular can also be especially pessimistic.