Will a relatively low LLU sync mean a low FTTC sync?

A question for the experts

Is it likely my relatively low sync on o2 LLU. . .


Downstream Upstream

Data Rate(Kbps) 12423 1204

Noise margin (dB) 6.1 6.1

Output power (dBm) 12.4 19.1

Attenuation (dB) 26.5 11.8


and tweaked


Downstream Upstream

Data Rate(Kbps) 14972 1213

Noise margin (dB) 1.2 6.1

Output power (dBm) 12.4 18.5

Attenuation (dB) 26.5 11.8

will cause speed issues with FFTC in the future?

I never resolved my situation when I was dealing directly with the upper echelons of Openreach a few years back. That was partly because I had other more pressing things to detal with so it all took a back seat.

Since a few new issues at the beginning of the year the connection has been pretty stable, no clicks or noise or SNR jumps but I do know for my attentuation I'm about 3-4MB down on where it should be and I don't want FFTC to be something of a damb squib when I eventually go down that route.

Edited by TheFunkySpy (Sun 13-Nov-11 16:53:52)

I wish I had your low sync!



FTTC speeds - this will depend on how close you are to your fibre cabinet rather than your current situation where it's how close you are to the exchange

As badger says, it depends how close you are to the cabinet.

Your attenuation is roughly as mine was before I went to FTTC, I'm getting the full forty down, no worries.

I agree for some reason or another you are missing some 6-8mbits of potential sync for that attenuation (if router reporting correctly) it could also be the router it's self, and how they at o2 have your line configured (level of interleave, and inpulse noise protection used) to answer your question, i suppose it would depend on which part of the line is the cause of this [censored] sync (, E or D side ) as FTTC would most likely only replace the e side ,exchange to cab (for bb) so if the reason that you are getting a low sync is down to the copper pair from the cab to your house then it may have an impact on the fttc service in some way, or it may not impossible to say but if it does and it's as bad sub 15mbit they may class it as a fault and swap the pair

Edited by tommy45 (Sun 13-Nov-11 14:16:28)

In reply to a post by TheFunkySpy:

A question for the experts

Is it likely my relatively low sync on o2 LLU. . .
will cause speed issues with FFTC in the future?

The only wires you have to worry about are from the cabinet to your house. Your ability to run a low noise margin indicates that will be fine, so I agree you'll get max sync.

Your ability to run a low noise margin indicates that will be fine, so I agree you'll get max sync.

Well, his sync at 6dB SNRM is low for the attenuation which possibly points towards more noise than usual.

However FTTC speeds and ADSL speeds (LLU or otherwise) have little to do with each other - assuming a 2km ish line there's still room for a 1km D side and relatively poor VDSL performance. OTOH he could be a few metres from his cabinet and get full sync, even next year when 80/20 comes along.

The important figures are what does the BT speed checker say when fed your phone number and how far are you from your street cabinet?

Ok thanks for those answers.

As I said Openreach never resolved my issues (I was with Be* at the time), the local exchange engineers never came up with anything although they agreed something strange was going on. I could have pushed the High Level Complaints, and indeed the Chairman at the time, team harder to get someone else out but I didn't. Over time the apparent random jumps in SNR (up to 2-3 dB) became less frequent. The jumps are minimal in size now and I don't monitor my connection constantly like I did in the past. I do get the occasional disconnect/LOF when tweaked but this is perhaps once a month rather than x amount of times a week (untweaked).

The basic sync speed has previously been in the 13.5 to 14MB region, but even tweaked it was rarely stable over 15MB. That applies to LLU with UK Online and Be*/O2.

BT's Infinity checker suggests 32 down 10 up, and at least if I go fiber and there's an issue I can be pretty certain it's between the home and cabinet.

I'll be waiting to see what Telefonica comes up with in the new year.

Edit - The cabinet is, based on presumed cable route, 465m from house. There is a closer cabinet 295m away. But I've always been led to believe it's one further away as it's nearer the exchange.

Edited by TheFunkySpy (Sun 13-Nov-11 17:27:16)