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still getting consistently less then IP profile

plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

still getting consistently less then IP profile

Hi Plusnet,
The training period has now completed and I am still getting consistently less speed than the IP profile. During peak hours this can get as low as 45% of IP profile speed, during off peak hours its about 15mbps slower than IP profile..
Sync speed has remained at 78mbps throughout the training period according to the members portal https://portal.plus.net/my.html?action=data_transfer_speed
Quote
Current line speed:
78 Mb

BT wholesale test reports (just now)
Quote
1. Best Effort Test:  -provides background information.
Download Speed
62.17 Mbps

0 Mbps 77.44 Mbps
Max Achievable Speed
Download speedachieved during the test was - 62.17 Mbps
For your connection, the acceptable range of speedsis 16 Mbps-77.44 Mbps .
Additional Information:
IP Profile for your line is - 77.44 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
16.1 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 16.1Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

Third party tests show pretty much the same result as the BT wholesale tester.
To see if this was router related I have swapped out the plusnet provided router for a third party PPPoE router (DDWRT) which experiences the same issues. All tests have been conducted via direct ethernet connection with no other devices using the connection at the same time.
Given my distance from the FTTC cabinet (~150m wire length, < 9 years old cabling), the given sync speeds and profiles I would be expecting consistently higher throughput, both up and downstream
Please can you advise the reason for the speeds being consistently lower than IP profile by 15mbps off peak times and about 30mbps peak times, as well as why my upload throughput never exceeds 85% of profile?
9 REPLIES
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: still getting consistently less then IP profile

Hi there,
I've checked over your connection and see as you stated that your sync speed has remained at 80Mb/s. There's no current capacity issues with your exchange either.
Would you be able to run through our faults wizard so we can investigate this further?
plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

Re: still getting consistently less then IP profile

Hi Chris,
As of this morning, things seem significantly better. While still lower than profile speed by a margin which seems quite high, I am now getting close to the speeds expected
69mbps down on a profile of 77.44
17.2mbps up on a profile of 20
Is this worth me opening a fault for if it now remains this stable?
It would be nice to get the full upload speed as I work for a major CDN and could do with the extra umph - given the things I have to send to customers over email and rsync - but im not going to get any lost sleep over 2mbps missing up and 9mbps missing down. Yeah its slower than im used to but if it remains consistent then is it really worth opening a fault? FYI, I don't think this is an upstream issue - we have a direct peer into plusnet via ae2.ptw-cr01.plus.net (this may indicate who I work for) and the bandwidth graphs there look healthy. I see the same transfer speeds there as i do from the BTW speed test.
I have ruled out issues on this side of the BTW modem, all CAT5 checks out at the correct speeds, tried different hard-wired machines in different switch ports and as I said the router has been swapped out, all to no avail. Ive got a spare Vdsl2 modem that I will change to at some point to ensure its not the modem itself at fault - that will also give me access to the bitloading on the line so can start graphing the vdsl health in case of future problems.
If you do think its worth opening a fault over this please do let me know. It does seem odd that im getting a drop below the profile with the exchange having capacity, equipment here checking out and my line being healthy. The only thing I can think of is perhaps there is some line problems and interleaving is spiking the latency, which is leading to congestion window at the TCP layer. That would make sense, but will know more when I hook up the new VDSL2 modem.
Is it now safe to connect my own VDSL2 modem given the training period has completed, and will there be any detriment? It is an official BTW modem (the Huawai one).
Thanks!

Quote
1. Best Effort Test:  -provides background information.
Download Speed
68.92 Mbps

0 Mbps 77.44 Mbps
Max Achievable Speed
Download speedachieved during the test was - 68.92 Mbps
For your connection, the acceptable range of speedsis 16 Mbps-77.44 Mbps .
Additional Information:
IP Profile for your line is - 77.44 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
17.2 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 17.2Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps[/quote[
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: still getting consistently less then IP profile

You'll be fine to swap over the modem, I'd suggest keeping an eye on your connection and if it remains where it is then it looks fine.
It seems there may have been a few issues last night - see here, that may not have helped your cause.
plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

Re: still getting consistently less then IP profile

Hi Chris,
I havent swapped the modem over yet as I havent had time, however the speed issue has returned this evening. I do note that even though my sync speed in the members area is still 78mbps my IP profile has been reduced from 74.44mbps to 70mbps - can you see why this is?
Quote
Current line speed:
78 Mb

Quote

1. Best Effort Test:  -provides background information.
Download Speed
50.64 Mbps

0 Mbps 70.4 Mbps
Max Achievable Speed
Download speedachieved during the test was - 50.64 Mbps
For your connection, the acceptable range of speedsis 16 Mbps-70.4 Mbps .
Additional Information:
IP Profile for your line is - 70.4 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
17.08 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 17.08Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

speedtest.net to namesco

I have raised the issue via the faults checker link you provided. I cant help but notice the correlation between these slow downs and evening peak usage times..
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: still getting consistently less then IP profile

Lets see if our faults team can identify any issues, your ticket will get updated as soon as there's any news.
plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

Re: still getting consistently less then IP profile

Hi Chris,
I didn't hear back during the 24h period promised on the faults checker, so left it a further 48 hours on top (with a request for an update in the ticket)  to see if anyone would get intouch. Ticket ID is 74575795. So I figured this afternoon I would swap out the modem and try to get some stats
Speed tests show that since I swapped out the VDSL modem, I get nearer (but still below) IP profile for downstream, and still never attain more than 75% of upstream profile, despite the profile being 20mbps and the physical line sync being on 20mbps.
Quote
1. Best Effort Test:   -provides background information.
Download Speed
68.04 Mbps

0 Mbps 69.75 Mbps
Max Achievable Speed
Download speed  68.04 Mbps
For your connection, the acceptable range of speeds  16 Mbps-69.75 Mbps .
Additional Information:
IP Profile for your line is - 69.75 Mbps
2. Upstream Test:   -provides background information.
Upload Speed
15.72 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed  achieved during the test was - 15.72Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

From the stats, Ive noticed a few things, first is the line attenuation is really bad for the length (especially in downstream band 1). I would expect to see a much lower attenuation for my distance to cabinet. I followed the wire along the length of manhole covers between my house and the cabinet and Im about 200m away according to my trundle wheel. The attenuation I am actually getting is what I would expect on a 500-600m line. I know lines are never 'as the crow flies', but I do draw upon my telecomms background (admittedly, mainly pre xdsl) to make a reasonable assumption about how these lines have been laid out on this 8 year old estate. Unless theres a several hundred metre loop of my pair under the ground somewhere, 7db attenuation is just pants for my distance. I picked this house in part because of its proximity to a FTTC cabinet, so to find I could have gone anywhere in a 500m radius and had the same performance is a bit of a let down.
Attenuation:
Quote
 VDSL Band Status        U0      U1      U2      U3      D1      D2      D3
 Line Attenuation(dB):  2.7     12.6    19.1     N/A    7.0     14.3    22.2

Theres also a discrepancy between path speed and the sync speed in both directions - is this normal?
Quote
Max:    Upstream rate = 22723 Kbps, Downstream rate = 72948 Kbps
Path:   0, Upstream rate = 20000 Kbps, Downstream rate = 72057 Kbps

And i also seem to be getting HEC errors in the downstream path. For 10,845 seconds of uptime is ~1000 HEC errors normal or acceptable?
Quote
Mode VDSL2  
Traffic type PTM  
DSL synchronization status Up  
DSL up time 10845  
  Downstream Upstream
Line rate (kbit/s) 72057 20000
CRC errors 0 0
FEC errors 16306 297
HEC errors 958 0

and finally, the members area sync speed indicator is, I think, broken. Im clearly syncing at just over 72mbps but members area still says 78 and has done since I joined.
Im guessing that the general reduction in IP profile is down to line conditions, but overall the above does not explain the peak time reductions in bandwidth that I am regularly seeing, or the inability for my line to exceed 75% of upload profile and sync speed. Ive lost 2mbps of upload in just a week or so (see pic in my sig - I was 17.8mbps up on 20mbps profile, but im now down to 15 after zooming down past 16 three days ago. If it keeps going like this ill be on 1meg within a month Wink
Plusnet Alumni (retired) chrispurvey
Plusnet Alumni (retired)
Posts: 5,369
Fixes: 1
Registered: ‎13-07-2012

Re: still getting consistently less then IP profile

I can see that our faults team have checked over your connection and have not found any fault with your line.
The HEC errors aren't too much of a concern on your line.
I've noticed that your sync speed has actually decreased further since you posted, it's now at 64.6Mb/s. Your line profile hasn't caught up yet so I'll give that a nudge to match it up.
I'd suggest monitoring your connection over a few days and see how your speed pans out.


plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

Re: still getting consistently less then IP profile

Thanks chris
The faults team replied with 'no fault' even though (as you see)  im now getting a sync speed which is even less than the conservative estimate on the BT wholesale line checker (which lists my line as 71.9mbps).
I also see that the max line rate is still high, but for some reason its the path which is limited. What is the reason for this?
Quote
# xdslcmd info
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 2
Max:    Upstream rate = 24713 Kbps, Downstream rate = 77832 Kbps
Path:  0, Upstream rate = 19499 Kbps, Downstream rate = 64601 Kbps

I also see retrain reason 2 here, which after looking at a few places shows a 'loss of framing'. I also see 13 CRC errors today.
How can the faults team say there is no fault with this data available to them?
plexy
Grafter
Posts: 38
Registered: ‎28-08-2013

Re: still getting consistently less then IP profile

Also just noticed as ive tried to play some games - ping has gone from about 8ms up to low-mid 20's, so I assume this is DLM kicking in?

Still sure there is no fault? Wink