Line attenuation help?

Hi, I am hoping an expert on here can help me make sense of my broadband challenge. We are 1 mile from the cabinet and have just upgraded to FTTC. We were previously getting 5.5mb download and 0.9mb upload on ADSL2+. Now on fibre we get 13mb download (which is much higher than I expected) and a 0.35mb upload. The upload speed is what we were hoping to improve and it makes no sense to me that the download would more than double, while the upload more than halved after moving to fibre. When I dug further into the stats I get more confused. The line attenuation for download is 29db, but for upload it's 79db. I thought that download attenuation would always naturally be a higher number than upload given the greater frequency applied to download on the line?? So I cannot fathom what is happening here? Please help!

Sounds like a problem. What modem are you using?

Please copy and paste the full stats .

Current rate (Kbps): 487(upstream), 17806(downstream)
Max rate (Kbps): 488(upstream), 17448(downstream)
SNR margin: 7.5(upstream), 5.4(downstream)
Line attenuation: 72.7(upstream), 29.1(downstream)
Error(pkts): 4658(upstream), 59203(downstream)

These are all the stats my router will provide. I have a TP-link router.

Thanks for helping!!

TP-Link archer vr600 ac1600

This is brand new as I wanted to try an alternative to the technicolor router from SSE.

Thanks for helping!

Summat not right there, have you anything else to test with, and maybe a description of the set up in the property ?

What are your WAN settings please? Including the ADSL/2/2+/VDSL2/All settings.

As others and you have said, those stats are crazy. The upstream suggests an ADSLx setup.

here are all the settings I can find on the router - not 100% sure what you need:

Internet Settings
Name: pppoe_ptm_101_2_d
MAC Address: 5A:C7:BF:01:A1:74
Subnet Mask: 255.255.255.255
Default Gateway: 62.72.136.44
Primary DNS: 89.145.254.78
Secondary DNS: 94.30.127.100
Connection Type: PPPoE

LAN settings
MAC Address: 50:C7:BF:01:A1:73
IP Address: 192.168.1.1
Subnet Mask: 255.255.255.0
DHCP: On

DSL settings (excluding ones already posted)
Line Status: Connected
DSL Modulation Type: VDSL2
Annex Type: Annex A/L

Other settings
WAN interface name: pppoe_ptm_101_2_d
VPI/VCI or VID: 101
DSL Modulation Type: Auto Sync-up
Bit Swap: Enabled
SRA: Disabled

All the additional parental controls and security controls are disabled.

Please let me know if I need to source any other data? This appears to be all my router has apart from he wifi settings, but i am hard wired currently.

Edited by deleted (Thu 01-Sep-16 15:16:54)

Also FYI. Using the advanced settings on the btwholesale speed checker, here are the IP profile stats for the line:

Download
Download speedachieved during the test was - 13.51 Mbps
For your connection, the acceptable range of speedsis 10.88 Mbps-15.55 Mbps .
IP Profile for your line is - 15.55 Mbps

Upload
Upload speed achieved during the test was - 0.38Mbps
Upstream Rate IP profile on your line is - 10 Mbps

The bit that surprises me is the IP profile on the upload side?

The upload speed should be over 1mb (it used to be around this on ADSL), but it cannot get about .38 and is usually .35.

Looks like you are indeed on VDSL {FTTC}.

The upload IP Profile merely denotes what package you're on. 10 = 40/10 or 55/10.

Edited by deleted (Thu 01-Sep-16 07:49:07)

Your upstream attenuation is the problem. Are you connected to the master socket, or are you using a telephone extension? Do you have other devices or connecting wires to the master socket?

Vdsl/wifi router is connected to the Openreach master socket. Nothing else connected to any other sockets in the house. I have a NAS drive and the tv coming out of the Ethernet ports on the router, but that's it.

Ummm. Need to think, but it would be a good idea to blank out the IP Address in the first section of your post. Google indexes these forums so it goes public.

Does the router connect to the socket with the DSL cable plus a filter, or do you use a plugin extension cable as well between the DSL cable and filter?

Do you have a phone plugged in anywhere? I know you've said nothing at any other sockets, but I've seen people not count the phone.

It would be a good idea to try connecting through the test socket inside the master. Also if you do have a landline phone available, make sure it doesn't work in any/all extension sockets while the master faceplate is off.

In reply to a post by Woodlee:

TP-Link archer vr600 ac1600
This is brand new as I wanted to try an alternative to the technicolor router from SSE.

It is possible the modem is misconfigured, you say an alternative to the technicolor so did SSE provide you with a modem for this service and if so have you tried using it ?
FYI on VDSL2 the uplink and downlink are interleaved across all frequencies and the start ABOVE the ADSL2/+ downlink, see here

"Interleaved" isn't a good word to use there, as it makes people think of packet interleaving.

I'm using an iPad at the moment so no CLI, but in the Windows CLI, running telnet to the modem, then the command on an unlocked Openreach HG612 to show what you mean is:-

xdslcmd info --pbParams

That shows how the down and up bin bands are interspersed.

Some modems will have a different command from xdslcmd, but it's the same as to get the normal stats, as in "something" info --stats and "something" info --show.

Agreed that the Upstream Attenuation seems very high.

My EE BB 2 does not give a figure for that; but earlier this week I noted a relative's figures on an HH 5 -

23.6 db Upstream Attenuation.

16.0 db Down Att - which seems reasonable at 350 Metres compared to 13.6 db for my 300 Metre line.

(The relative is having problems. Without re-setting, his Download speed jumped from around 22 Mbps Down to 45 Mbps Down, whilst the corded phone worked fine on the QLT, under both conditions.)

---------

I was also wondering about the OP's SNR Margins of-

7.5 db Up, 5.4 db Down.

These seem tight compared to my relative's 6.3 U and 14.1 D (but wondering about the 6.3 Up)

My SNR Margins are-

22.2 Up and 18.1 Down

Are the other sockets in the house still operational and are they connected to the master socket faceplate?

I not sure if there is actually anything signifacantly wrong and that it is just down to the line characteristics.

I have had a look at the estimates for a line I know and they are:

Clean: Down -17.8/11.8 Up - 1.2/0.8
Impacted: Down - 15.9/5.7 Up - 1.2/0.6

So, in the same downstream range as yourself and whilst the upstream is estimated to be greater than yours it is only just above your original ADSL speeds. What did your pre-install estimates suggest?

Can you use DSL Stats and get a screen shot of the Bit Loading with SNR overlay?

The attenuation relations between upload and download and very different on VDSL to ADSL2+

Am away so going on memory, first band is download on VDSL2, followed by upload in a higher band, i.e. D0,U0, D1, U1 D2, U2

I suspect line length means DO is roughy okay hence the download giving something, but very little use made of U0 due to the line length and very few usable bits available there, then D1 and further up spectrum totally unavailable.

For those who haven't seen what is being described about the frequency/bin layout:-

# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status:   0
Max:    Upstream rate = 13850 Kbps, Downstream rate = 56880 Kbps
Bearer: 0, Upstream rate = 13835 Kbps, Downstream rate = 57825 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) (1972,2774)
DS: (33,859) (1216,1961) (2793,3970)

VDSL Port Details               Upstream                Downstream
Attainable Net Data Rate:       13850 kbps              56880 kbps
Actual Aggregate Tx Power:         7.4 dBm               13.5 dBm
===============================================================================
VDSL Band Status        U0    U1     U2     U3   U4     D1   D2     D3
Line Attenuation(dB):   5.3   30.3  46.2   N/A   N/A  14.7  37.9  59.2
Signal Attenuation(dB): 5.3   29.3  45.0   N/A   N/A  19.5  37.5  59.3
SNR Margin(dB):         6.7    6.2   6.2   N/A   N/A   6.1   6.1   6.1
TX Power(dBm):          0.8  -12.1   6.3   N/A   N/A  11.0   7.9   5.6
#

The interspersing is seen in the "Band Plan" sections.

This is really interesting. Is there a way I can pull up here stats on my router? Not sure how to get to the command line? Thanks!

This is really interesting as all new news. Is there somewhere I can read a bit more about this?

What router is it please, or modem if you have a separate one?

Are you using a Windows or Apple computer?

Ok done some more reading and this is really interesting. please can I check I have understood correctly, because if I have then it still doesn't quite explain why my upload speed has halved. Here is my logic: on ADSL I would have consumed an upload bin with a range of 6khz to 31khz. However when moving to VDSL I would be consuming a band from 7khz - 32khz. My logic is that if I got 1mb on ADSL, I should still get that on VDSL as the frequencies of the camparitove bins are virtually identical?????

However what you have described explains why I wouldn't get anymore than 1mb, because the next chunk of upload frequency starts at 871khz and my line is too long, that bin is unusable.

Sound right???

I have two router options available:
TP-Link archer vr600 ac1600
Technicolor VDSL router

I am on an Apple Mac.

Thanks!

In reply to a post by Woodlee:

Sound right???

NO!

ADSL2+ uses the frequencies from around 25kHz up to 138 kHz for the up stream and VDSL is similar although a lot of user see low fill rates on the first three or four tones. The next upstream starts around 3.75MHz.

This is why I asked for a Tone plot from DSLStats if you can obtain one.

DSLStats runs on Mac OS under Wine. I think DSLStats supports the Technicolor. http://www.s446074245.websitehome.co.uk/routers.html