Womble paging Zarjaz......

Just a quick question; have you ever come across problems where poor xDSL broadband performance is due to a split pair? Or, do you know how common split pairs for POTS are?

I'm starting to suspect that might be an issue on the one line I've had long term problems with.

Edited by caffn8me (Wed 10-Jan-18 20:29:06)

Yes I have, in one extreme case, ( the pair �leg and leg� for a couple of hundred meters) you could sync up at different speeds (back in fixed speed days ) one sync at half a meg, then drop sync, resync and see 1 meg.

Split pairs are thankfully rare.

You can, with a decent mole/tdr �see� a blip at the start and finish of the split .... but not always. Good old fashioned legwork is the way forward.

What are the symptoms you are seeing ?

.... oh yeah, again with an old style mole you can �see� the other pairs digital signal making the read out line �tremor�. It won�t show where it is, but will show its presence.

I would expect a line suffering to have a high error count, and a lower than expected sync rate, maybe even random drops ..... so yes, the same symptoms of many other issues ...

Thank you very much for the quick reply It's greatly appreciated.

This is the problem I referred to back in " Six master sockets on one line"

Downstream is now showing attainable of 36.2Mbps down and 5.3Mbps up. The Openreach DSL tester shows an impacted line should be capable of between 62Mbps and 39.8mbps down and 19.5Mbps and 10.7Mbps up.

POTS tests fine and a quiet line test shows nothing.

The office next door, which is connected to the same DP and DSLAM, has a current sync of 80000/20000.

I'm trying to persuade someone to send an Openreach engineer and a JDSU out to show there really is a problem. This is after having tried with four different VDSL2 modems (al different brands) and replacing all the wiring from DP to master socket (which was copper coated steel).

The DP is on the front of the building between the two offices at first floor level and the multipair feeding it comes over the roof. I'm wondering if someone got a bit distracted while wiring things up a ladder many years ago and there's been a split pair ever since.

We need to start doing offsite backups and the connection speed isn't close to good enough. Next door's works fine for offsite backups.

Error seconds are showing at about 15,000 but I'm not 100% sure what period that relates to. CRC errors are several per minute. I've just restarted the router to see what sort of error rate I get from a clean slate.

I remember that thread ....

What you�ve got to do I reckon is ;

A. Hope you get an Openreach engineer who has a scooby, and will listen to ..

B. Get the directory number of the 80/20 syncing circuit of the same DP.

.. this is clear evidence that the line question is not right somewhere. They engineer should be able to get the OGEA reference of the other line and run a remote test to prove the 80/20 is possible. Duff DSLAM port ? Naff pair ?

I did a job were the end user had NDT so i got him DT on a spit pair / leg and leg but he then lost his BB ! so he asked me to put it back on a real pair as for him NDT was better then no BB.

So yes a spit pr is very bad for BB.

That don�t sound healthy do it.

The last Openreach engineer had a JDSU and suggested that although things weren't great when he tested, they'd get better as DLM eased up. Of course they didn't.

I thought duff DSLAM port initially and the engineer previously did a port and pair swap. There were two active pairs with POTS coming into the building. One of these has now been ceased. The engineer put the VDSL2 on the better of the two as the pair it was originally on was marginal for DC balance.

I'm a technical contact with the ISP for the line next door too, which helps.

Thank you very much for the pointers.

Nope, not healthy. And when Zen ran remote tests previously, the line in this office showed up as 600m longer than the line next door