topic Re: Fibre 80/20 speed expectations in Full Fibre

Fibre 80/20 speed expectations

ncd — Sat, 21 Dec 2019 13:30:18 GMT

Hi Plusnet team and forum,

I've had a ticket (195816868) open for a while with the support team discussing the speed of my connection.

My house is very close to the green cabinet (line test is reporting ~136m and we can see from the window!) and yet I don't seem to be able to exceed ~70Mbps down. My upload is ok maxing out at 18.7Mbps (~93% of 20Mb) but download I can't seem to improve.

I've tried replacing the ECI modem I was originally issued with, trying a Huawei HG612, Vigor 130 and now a Zyxel. None of these have made any real difference to the download I'm able to achieve. The line is quiet with no noise and nothing else plugged in.

My sync speed is good:

Max: Upstream rate = 26071 Kbps, Downstream rate = 102334 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps

And the SNR is solid:

           Down Up
SNR (dB): 11.3 10.6
Attn(dB): 7.4 0.0
Pwr(dBm): 13.0 -12.8

So my question would be what is the max actual download rate that can be attained with an 80/20 vdsl connection?

I've had friends and colleagues mention 75/76 down but I'm not able to get close to that even though I'm much closer to the cabinet than they are and also have a much better signal stats than they do.

Is 75/76 a pipe dream?

Thanks!

Re: Fibre 80/20 speed expectations

TheMightyAJ — Mon, 23 Dec 2019 21:03:19 GMT

Hi @ncd,

This all depends on the quality of the line, which can change and fluctuate over time. In theory you should be able to reach up to around 76Mbps based on the package we offer, though that is dependent on the estimated speeds for your line.

Re: Fibre 80/20 speed expectations

ncd — Tue, 24 Dec 2019 16:12:42 GMT

@TheMightyAJ thanks for your reply.

What factors could affect the max speed? I have really good signal to noise ratio and the connection is rock solid so I wouldn't expect DLM to be kicking in.

I'm synced at 80/20 but hey can't achieve more than 70 on the download.

Apologies for the 101 questions! I'm keen to get the max out of what I have especially when I'm so close to the cabinet.

Re: Fibre 80/20 speed expectations

idonno — Tue, 24 Dec 2019 17:10:20 GMT

@ncd wrote: What factors could affect the max speed?

Crosstalk is usually one issue if you are not achieving max throughput. Mine took a dive as more and more people locally took up fibre. In the heady days, 78mb was what I got on the various speedtests sites. Then it slowly sunk. School holiday times was good as the various families went away, so the download speed improved.

While it is nice to have max through put, is it really making that much difference? I just came to accept what I got coming down the wire. I've even stopped (for the most parts) doing speed tests!

Re: Fibre 80/20 speed expectations

ncd — Tue, 24 Dec 2019 17:17:34 GMT

@idonno thanks for the info re crosstalk. I'm guessing there is little we can do on this?

You're right that most of the time it makes no real difference to me but I have just moved backup provider so have had to resync a lot of data both up and down so a few extra mb makes a lot of difference in terms of how long it takes for each dataset.

Re: Fibre 80/20 speed expectations

Mustrum — Tue, 24 Dec 2019 17:31:40 GMT

Crosstalk affects sync speed, not throughput directly.

Throughput can be affected by other traffic, either from other applications on your laptop/PC, or other devices on your network.

That said, you won't get too much more throughput when testing, but make sure its from a wired port, switch wifi off.

Re: Fibre 80/20 speed expectations

Kevin — Tue, 24 Dec 2019 18:07:59 GMT

@ncd , out of interest, do you have a static IP address?

Re: Fibre 80/20 speed expectations

ncd — Tue, 24 Dec 2019 18:16:21 GMT

@Mustrum - Thanks!

Sync speed is good - 79999/20000 so almost 80!

For the purpose of these tests I've been connecting a host directly to the router (which is good for ~1Gbps). Wifi is not on this router. I've also tried establishing ppoe directly from a host to the modem to see if that helps. It doesn't! I've also done a packet capture whilst testing to confirm there is no other traffic during the test.

That said, you won't get too much more throughput when testing, but make sure its from a wired port, switch wifi off.

What do you mean by not get much more? Is there different a theoretical limit? From my recent reading I was under the impression that the maximum possible throughput was around 96.8% of sync speed which would take me to ~77Mbps as a maximum possible. That additional 7Mb or 10% would make a difference of several hours on my sync back to home!

Re: Fibre 80/20 speed expectations

ncd — Tue, 24 Dec 2019 18:17:56 GMT

@Kevin - I do yes, I really hope this doesn't affect things!

Re: Fibre 80/20 speed expectations

Kevin — Tue, 24 Dec 2019 18:26:46 GMT

Unfortunately, yes it does. My current sync speed is 85 ish Mb and my max download speed via all the different speed testers is only 69Mb.

It's something to do with the way the Plusnet profile system handles static IP's.

This is from a post by @ejs earlier this year....

Some of us who have been here a bit longer than others may be well aware that an apparently correctly set Plusnet profile, when being applied, will always reduce your speed by a small but noticeable amount compared to exactly the same connection without the Plusnet profile being applied.

For reference:

https://community.plus.net/t5/Plusnet-Feedback/Affect-on-speeds-of-the-Plusnet-profile/td-p/991521

http://forums.thinkbroadband.com/plusnet/4428998-pn-ip-profile-and-bt-ip-profile.html

So I'd expect a static IP will always slightly reduce the throughput due to the effect of the Plusnet profile. It's all ancient history and no longer an issue for most customers, who are not on static IPs, and so the Plusnet profile is not applied to their connection.

------------------------------

So despite having a full speed Sync, my Plusnet current line speed is only 73.8Mb!

Re: Fibre 80/20 speed expectations

RealAleMadrid — Tue, 24 Dec 2019 23:27:17 GMT

This is definitely a Profile issue, the reply from @TheMightyAJ is not at all helpful or correct. If the line is syncing at full speed, the line quality is obviously good. It can't be any better than that.

I queried this low IP profile problem recently see post 20 of this thread ...

https://community.plus.net/t5/Everything-else/Monitoring-Throughput/m-p/1694371#M22933

the response was not clear, there is something going on with the BT wholesale IP profile calculation using a reduced sync speed value when the line is running on retransmission high which is one of the G.Inp operating states for longer lines where there may be more errors detected. . Although I have no errors showing my line is in this state and my IP profile is about 88% of the sync speed, then the PlusNet profile may or may not knock this down a bit more possibly depending on whether you have a static IP. I was not on a static IP and only got a throughput speed of about 65Mbps with a full 79.999Mbps sync speed which is not good.

I have just gone to a static IP and will see if anything changes, I feel I am losing a lot of potential speed because of the profile system.☹️

Re: Fibre 80/20 speed expectations

MatthewWheeler — Fri, 27 Dec 2019 16:19:09 GMT

Thanks for getting back to us @ncd

We've retested your line and there are no profiles on our end nor our suppliers that would be causing this.

I'm happy to try removing your static IP to see if that gives you an increase but due to you having a block of static IP's I can't gurantee that you'd get these back and they'd be most likely a different range

Re: Fibre 80/20 speed expectations

ncd — Fri, 27 Dec 2019 16:43:27 GMT

@Kevin @RealAleMadrid thanks for both of your replies.
Did you ever get it sorted as it sounds like a well known issue?

Re: Fibre 80/20 speed expectations

ncd — Fri, 27 Dec 2019 16:45:48 GMT

@MatthewWheeler thanks for the reply and kind offer but I'm not happy moving to a dynamic ip.

It sounds like this is a well known issue as several other people have reported they are affected both in this thread and other threads they have linked to.

What can we do to get this investigated further?

Thanks again!

Re: Fibre 80/20 speed expectations

Kevin — Fri, 27 Dec 2019 18:37:22 GMT

@ncd I keep wondering if I really need a static IP. Think I've had it since I joined the original fttc trial.

I'm about 300 odd metres from my cabinet, so although I sync at the max 80Mb, I doubt I will reach the theoretical max.

One day I'll have it taken off, just to see how much speed I actually gain. Probably only another couple of Mb's!

The only streaming problems I have is SkyGo, and that is more down to their rubbish player. Netflix, Iplayer (and the other channels players) and Amazon Prime all work fine.

So it's only bragging rights really!

Re: Fibre 80/20 speed expectations

fwdlink — Sat, 28 Dec 2019 16:30:50 GMT

@RealAleMadrid @ncd

Both thanks for your input so far, I have EXACTLY the issue you have both been describing.

My cabinet went offline back in November overnight and when it came back up, my neighbors and I all seemingly had a DLM reset and we noticed looking at our status that for the first time ever we had G.INP applied to the Upstream and my line also received a greater than 50 G.INP setting, in my case 55, it was 47-49 on average mostly impacted by my cross-talking neighbor. When she turns her modem off and I leave things a good 24 hrs I would normally get a full 79999 sync and 47 G.INP for DL.

Ever since the cabinet came back with the new capabilities I've been stuck at a throughput of 67Mbps, however I'm synced at 79999/20000. @Gandalf did mess with my profile and got me up to 72Mbps but that lasted only until the DLM decided to take action when my neighbor came home and fired up her modem and voila 24hrs later I went from 49 back to 55, still sync though at 79999. I'm guessing I'm on a retry "high" and affected by this anomoly...it's frankly making me crazy as we tend to do 4k streaming and one stream alone will avg 30-40mbps, we do max our line out in the evenings with 2 streams and whatever elso going on so my view is I'd like the line to not be hobbled.

Reading through your posts it sure sounds like my issue is similar, it's very frustrating as the line is stable and will go for months on end without a resync.

Strangely my PN Dashboard says my sync is 72.1Mbps, but PN staff tell me to ignore this, I'm wondering if this is the multiplier that is being taken from IP Profile and Retry High params, would make sense as I'm sure there's some overhead in the calculation as when I had no issues I would get around 76Mbps throughput consistently, but the dashboard would show my true sync speed and the average would be closer to 76Mbps.

My stats:

DSLAM type / SW version:	BDCM:0xa48c (164.140) / v0xa48c
Modem/router firmware:  	AnnexA version - A2pv6F039v.d26a
DSL mode:               	VDSL2 Profile 17a
Status:                 	Showtime
Uptime:                 	16 days 4 hours 29 min 52 sec
Resyncs:                	1 (since 12 Dec 2019 01:13:33)
			
				Downstream	Upstream
Line attenuation (dB):  	11.9		0.0
Signal attenuation (dB):	Not available on VDSL2		
Connection speed (kbps):	79999		20000
SNR margin (dB):        	4.8		7.8
Power (dBm):            	13.9		-1.9
Interleave depth:       	8		8
INP:                    	55.00		47.00
G.INP:                  	Enabled		Enabled
Vectoring status:       	5 (VECT_UNCONFIGURED)		

RSCorr/RS (%):          	1.8551		156.1647
RSUnCorr/RS (%):        	0.0000		0.0000
ES/hour:                	0.18		5.73

Connection stats

xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 23738 Kbps, Downstream rate = 85031 Kbps
Bearer: 0, Upstream rate = 20000 Kbps, Downstream rate = 79999 Kbps
Bearer: 1, Upstream rate = 0 Kbps, Downstream rate = 0 Kbps
Link Power State:       L0
Mode:                   VDSL2 Annex B
VDSL2 Profile:          Profile 17a
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        4.8             7.8
Attn(dB):        11.9            0.0
Pwr(dBm):        13.9           -1.9

Re: Fibre 80/20 speed expectations

ncd — Sat, 28 Dec 2019 16:59:17 GMT

Hi @Kevin, All,

@Kevin wrote:

@ncd I keep wondering if I really need a static IP. Think I've had it since I joined the original fttc trial.

I do use the static IP, mainly when developing things at home before hosting somewhere more permanent. I could use dyndns or similar but the static IP with a DNS alias is much easier.

I'm about 300 odd metres from my cabinet, so although I sync at the max 80Mb, I doubt I will reach the theoretical max.

One day I'll have it taken off, just to see how much speed I actually gain. Probably only another couple of Mb's!

I'm about half of that distance but do have the lovely view of the cabinet from the house 😉

I'd like to think we can get closer to the theoretical max than we are today or if not understand why it's not possible.

The only streaming problems I have is SkyGo, and that is more down to their rubbish player. Netflix, Iplayer (and the other channels players) and Amazon Prime all work fine.

It's less about streaming not working for me, I use an offsite backup provider and happened to move provider so ended up resyncing a lot of data which got me looking into my maximum rates a little further. A few Mb increase can really make a difference in this scenario but for the most part it's fine.

So it's only bragging rights really!

I've already lost that one unfortunately with several friends and colleagues on G.fast!

Cheers,

Re: Fibre 80/20 speed expectations

ncd — Sat, 28 Dec 2019 17:11:31 GMT

Hi @fwdlink

This does indeed sound very similar. I'd be happy with 76Mbps as that's ~10% increase on what I have today and would make a difference to my use case.

I'm keen to get to the bottom of this problem too, if not to improve but to understand what is going on.

For completeness I'll also post my stats:

==================================================================================== VDSL Training Status: Showtime Mode: VDSL2 Annex B VDSL Profile: Profile 17a G.Vector: Disable Traffic Type: PTM Mode Link Uptime: 3 days: 22 hours: 57 minutes ==================================================================================== VDSL Port Details Upstream Downstream Line Rate: 20.033 Mbps 79.998 Mbps Actual Net Data Rate: 20.000 Mbps 79.999 Mbps Trellis Coding: ON ON SNR Margin: 11.0 dB 11.4 dB Actual Delay: 0 ms 0 ms Transmit Power: -12.5 dBm 13.0 dBm Receive Power: -18.7 dBm 6.2 dBm Actual INP: 0.0 symbols 48.0 symbols Total Attenuation: 0.0 dB 7.5 dB Attainable Net Data Rate: 26.579 Mbps 102.155 Mbps ==================================================================================== VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3 Line Attenuation(dB): 1.8 4.6 7.4 N/A N/A 4.2 8.1 12.6 Signal Attenuation(dB): 1.8 15.5 6.6 N/A N/A 5.0 8.0 12.6 SNR Margin(dB): 10.9 11.0 11.0 N/A N/A 11.4 11.3 11.4 TX Power(dBm): -25.9 -41.1 -12.7 N/A N/A 9.7 7.8 7.0 ====================================================================================

The last reset was due to my messing, it's normally rock solid.

You mentioned that you had been working with @Gandalf on this issue and you were able to have an improvement until DLM happened? Do you have a link to the thread and what was actually changed?

Thanks!

Re: Fibre 80/20 speed expectations

Kevin — Sat, 28 Dec 2019 18:05:14 GMT

My current Smart Hub 6 (Business) stats....

DSL uptime:

8 Days, 14 Hours 16 Minutes 56 Seconds

Data rate:

20.00 Mbps / 80.00 Mbps

Maximum data rate:

30882 / 84981

Noise margin:

12.7 dB / 3.9 dB

Line attenuation:

0 dB / 14.2 dB

Signal attenuation:

0 dB / 14.2 dB

VLAN id:

101

Modulation:

G_993_2_ANNEX_B

Latency type:

Fast Path

From member centre.....

Current Line Speed (Download): 73.8Mbps

I can't do a speed test at the moment as Netflix is being watched!

Re: Fibre 80/20 speed expectations

Gandalf — Sun, 29 Dec 2019 18:19:59 GMT

Hi @ncd I've looked into this and it's an odd one but there isn't anything we can do remotely I'm afraid. Everything on our testing checks out OK with your sync speed at 80mbps, the profile on your account at 78mbps the highest it goes.

The banding on your line is: "Downstream: 0.128M-80M with Retransmission (Low). Upstream: 0.128M-20M with no error protection" which shows you're on an open unrestricted banding.

We could arrange an engineer visit to investigate this, although the chances they'd be able to fix this are likely to be minimal.

Hi @fwdlink One of my colleagues has responded to your other thread, with regards to the connection profile on your account this isn't actually affecting your speeds because you don't have a static IP.

This profile is just something that should always match the IP profile of the line and if it's set underneath this and if you have a static IP it'll then restrict your throughput.

Unfortunately the problem appears to be the IP profile which we've got absolutely no control over I'm afraid. I'm happy to arrange an engineer to investigate this if you'd want but I'm not confident this is something they'd be able to look into.