topic Re: Bridge tap in Broadband

Bridge tap

greygit — Sun, 31 Jul 2022 00:32:41 GMT

I've an odd status for 'bridge tap' when querying https://www.broadbandchecker.btwholesale.com/#/ADSL

Bridge tap is showing as 'U'.

I'm assuming that is a representation of 'status Unknown' (rather than N for 'No' and Y for 'Yes'), and I can't think of another explanation.

Is there any way that the ambiguity of the status of Bridge Tap can be resolved? The existence of a bridge tap has implications for performance on a VDSL line.

Re: Bridge tap

Mustrum — Sun, 31 Jul 2022 00:37:09 GMT

Disconnects everything from the master socket untill the status changes - then add one item at a time until you get the same result.

Re: Bridge tap

greygit — Sun, 31 Jul 2022 00:49:36 GMT

Done that multiple times. No change in status. Unless you mean that stuff has to be disconnected for more than a few minutes. (Days, years?).

There's only a single landline and a DSL modem connected. No internal phone extensions/cabling.

The mk4 faceplate of the 5C 'master socket' is disconnected . Multiple filters used. But it is still the same. As it has been for quite a long time.

And if everything is disconnected how can I discern whether the status has changed?

Re: Bridge tap

Gandalf — Mon, 01 Aug 2022 13:12:58 GMT

Are you having any issues with your service?

Re: Bridge tap

greygit — Mon, 01 Aug 2022 22:41:31 GMT

Actual linespeed has recently been below what it has been. I suspect banding has been implemented. I was recently following advice about disconnecting stuff, and that (seemingly) resulted in a further drop in actual linespeed. I'm of a particular opinion of how software 'manages' what it sees as unexpected interruptions (IYSWIM).

Peak physical - reported - linespeed (as opposed to what is achievable) has been above the 'handback' VDSL levels (for an 'impacted line' which includes bridge taps as an excuse). The same linespeed is below what it has been.

From my perspective there's no incentive to upgrade to VDSL (with its additional financial outlay) with the current status as I could end up with a degraded service (/if/ the actual linespeed gets back to where it was).

I thought bridge taps may be near to customer premises, but won't be *in* the customer premises?

N.B. a few years back I did have an occurence of a 'crossed line' and listened to someone else's telephone conversation. I'm wondering whether the reporting of that (to Plusnet) led to the 'U' designation for bridge tap.

I could conceivably pop over to Sheffield to discuss this further.

Re: Bridge tap

jab1 — Tue, 02 Aug 2022 06:22:58 GMT

@greygit wrote:

I could conceivably pop over to Sheffield to discuss this further.

You could, but it would be a wasted trip - there is no public access to Plusnet HQ.

Re: Bridge tap

Gandalf — Tue, 02 Aug 2022 09:41:47 GMT

There's no banding on your speed as that's showing at "WBC 160K - 24M Medium delay (INP 1) 6dB Downstream, UC Low delay (INP 0) 6dB Upstream (ADSL2+)" but testing your line is showing "HIGH RESISTANCE IMBALANCE DETECTED".

Is your router plugged into your master telephone socket with no extension cabling between the socket and router?

As for coming to see us in Sheffield, legend has it that it's harder to get into the office than Fort Knox.

Re: Bridge tap

greygit — Wed, 03 Aug 2022 00:31:54 GMT

Since posting, and seemingly nothing being done, my line is returning to what it was before the OR engineer visit.

(The reported 'noise margin' on the hub2 does appear to be dynamic - it changes).

To answer your question. The hub2 is currently plugged into the filter that shipped with it. The (recently installed) mk4 faceplate is having a rest on the floor. There are no telephone extensions in the house. The only devices connected to the BT 'master' socket are the hub2 and a telephone.

An 'interesting' BT speed test from the 27th July.

Not that 'bad' for a flakey ADSL connection, eh?

But two minutes later...

Other (previous) tests results (23rd July)...

Re: Bridge tap

Mustrum — Wed, 03 Aug 2022 01:05:06 GMT

Why not report the rest of the BTW DSL checker https://www.broadbandchecker.btwholesale.com/#/ADSL hiding your phone number?

Re: Bridge tap

jab1 — Wed, 03 Aug 2022 06:14:28 GMT

Following @Mustrum 's suggestion above, it might be an idea to report also your full Help Desk page and an up-to-date speed test. I'm confused - how come you have a Hub2 on an ADSL connection.

By the way, the SNR figures on any modem/router are dynamic, as circuits are affected by varying conditions.

Re: Bridge tap

Gandalf — Wed, 03 Aug 2022 08:45:02 GMT

At one point not long ago we had a stock issue with the Hub One, so we sent some customers a Hub Two instead.

I think it's worth arranging another engineer to investigate further. When could you be available for a visit? The engineers are available weekday timeslots (and occasionally Saturday's) of 8am to 1pm or 1pm to 6pm.

Re: Bridge tap

jab1 — Wed, 03 Aug 2022 08:47:01 GMT

@Gandalf OK - I wasn't aware of that - just thought I'd ask 😉

Re: Bridge tap

jab1 — Wed, 03 Aug 2022 17:52:51 GMT

@greygit I would also be asking why your SNR figures (both directions) are so low - this certainly won't be helping.

Re: Bridge tap

greygit — Wed, 03 Aug 2022 22:01:32 GMT

"how come you have a Hub2 on an ADSL connection."

It's what PN sent me when I renewed the contract.

I know the SNR figures are dynamic.

Re: Bridge tap

greygit — Wed, 03 Aug 2022 22:02:33 GMT

Thanks for taking the time to do that check. Appreciated.

Re: Bridge tap

greygit — Wed, 03 Aug 2022 22:58:25 GMT

"@greygit I would also be asking why your SNR figures (both directions) are so low - this certainly won't be helping"

Oddly I am getting better line/actual speeds with those (marginal?) SNR's compared with the lower line/actual speeds with a higher SNR (that's the SNR/line speeds when having the mk4 faceplate in place). Unless the Hub2 isn't reporting correct SNR. The last OR eng appeared to suggest he had better SNR than the Hub2 was reporting, and that the figures varied.