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Author Topic: Fourth line goes in next Wed  (Read 19621 times)

johnson

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Re: Fourth line goes in next Wed
« Reply #30 on: August 09, 2018, 06:10:18 PM »

Did you swap it out and then in again to prove the modems fault? I'd be wary of jumping to any more conclusions if not.
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Weaver

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Re: Fourth line goes in next Wed
« Reply #31 on: August 09, 2018, 07:22:50 PM »

Put another modem onto that line, put that modem onto another line. Those were the tests done, amongst others. Will re-examine the modem later on. Now, with that modem gone, the line is well-behaved, no flapping, no catastrophic packet loss.
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johnson

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Re: Fourth line goes in next Wed
« Reply #32 on: August 09, 2018, 07:35:20 PM »

Sorry if I'm being slow, but you put the faulty modem on another line and it produced the same very low sync?
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Weaver

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Re: Fourth line goes in next Wed
« Reply #33 on: August 09, 2018, 10:07:10 PM »

We put the faulty modem in a good line and no sync that time in fact. Janet came and did the plugging and unplugging for me. But we did not get any further into testing of the accused modem  after those two critical tests which were: good modem on accused line, accused modem on good line. This was because we did not want to get started on something more substantial when the BT man was due any minute. Mind you, that ‘any minute’ thing remained true all day as we had no idea when to expect him.
« Last Edit: August 09, 2018, 11:29:14 PM by Weaver »
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Weaver

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Re: Fourth line goes in next Wed
« Reply #34 on: August 09, 2018, 11:31:25 PM »

@johnson also the problem modem was resynching every so many times per hour for 12 hours, until in the end I woke up and dropped it from the bonded set as also it had huge packet loss which was polluting the rest, duh. :-[  :'(
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johnson

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Re: Fourth line goes in next Wed
« Reply #35 on: August 09, 2018, 11:52:51 PM »

I don't doubt that the modem on that line was misbehaving, I'm just uncertain of the failure modes that could cause a spontaneous modem death. High voltage spikes on the line input, extremes of temperature maybe? But without these circumstances I'd be inclined to think the modem was not at fault and maybe an unfortunate set of conditions when testing made it seem like it was. Could be very wrong obviously, with the number of 1312s you have the chance of a faulty device goes up a good deal.

Well once you have thoroughly confirmed its for the bin you know where to post it! :D

Edit: Or does the chance go up that much? I probably need to brush up on my bayesian inference..
« Last Edit: August 09, 2018, 11:59:05 PM by johnson »
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Weaver

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Re: Fourth line goes in next Wed
« Reply #36 on: August 10, 2018, 12:01:12 AM »

Assuming it is indeed dead or ill, retest pending either as a sanity check or in case it was somehow temporary, since it is so suspicious that it chose that day to die, I wonder if there is any possible way in which BT fiddling about could have killed it remotely? I can't see it. One or two staff are a bit clueless. Like the guy who shorted out the Broadford exchange a couple of years back by letting a piece of solder or a piece of wire fall into the wrong place or similar, not at all sure of the exact details. That caused me a repeated problem short term, but did not kill any kit, unsurprisingly.
« Last Edit: August 10, 2018, 12:05:48 AM by Weaver »
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burakkucat

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Re: Fourth line goes in next Wed
« Reply #37 on: August 10, 2018, 12:06:18 AM »

I would be inclined to give the device a good period of time without any power then, after powering up, reset it to the factory defaults.
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johnson

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Re: Fourth line goes in next Wed
« Reply #38 on: August 10, 2018, 12:06:36 AM »

Not sure what they could do other than short the pairs. Would some clumsy fingers in a cabinet or poor procedure of disconnecting and reconnecting cause damaging spikes? I honestly have no idea.
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Weaver

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Re: Fourth line goes in next Wed
« Reply #39 on: August 10, 2018, 12:10:29 AM »

@johnson if the probability of failure is low, then approx it is the sum of the probabilities. More accurately though it is 1 - ( 1 - p iirc. Memory fades, but you just apply the binomial theorem to that expression and dump higher power terms and that gives you the approximation - eg for 2 units, 1 - ( 1 - 2p + )2p, or in general np or, more generally still, the sum of small probabilities.
« Last Edit: August 10, 2018, 12:30:53 AM by Weaver »
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johnson

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Re: Fourth line goes in next Wed
« Reply #40 on: August 10, 2018, 12:28:48 AM »

I'l take your word for it, my brain was going down the line of "If the modem tests as failed and the test is highly accurate but the likelihood of a modem failure is low" etc etc, but I know better than to get into an argument about probability with a physicist.
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Weaver

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Re: Fourth line goes in next Wed
« Reply #41 on: August 10, 2018, 12:33:48 AM »

A physicist who knows nothing about stats, amazingly, because I was a theoretician solely, and so did not do a lot of modules at all, and no lab work after term 4, but experimentalist would definitely have to learn it yet why we all didn't, not just the ten theoreticians, is very odd.
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Weaver

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Re: Fourth line goes in next Wed
« Reply #42 on: August 10, 2018, 01:55:11 AM »

Anyway, no show today, so we now see if anything happens on friday and then } while ( true );. I was told to let A&A sales know about the no-shows, so I dropped them a line late this afternoon.

Openreach I think charges you, what, £90 if you are not there to let them in. So how much do I charge them, £180 for being two days late? It is a good think I did not have to take two three days off work waiting in for the man. But cynically maybe because here is here, they assume that no one could conceivably ever be out to work in the day, not without a wifey left in the kitchen. :o I sincerely hope and expect not. [Unfair.]
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Weaver

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Re: Fourth line goes in next Wed
« Reply #43 on: August 10, 2018, 09:56:46 AM »

Side track: I saw this post this morning: https://forum.kitz.co.uk/index.php/topic,14362.msg268409.html#msg268409

Is this me?

And a beginner's question, just checking my understanding: What exactly is the definition of a DP?
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burakkucat

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Re: Fourth line goes in next Wed
« Reply #44 on: August 10, 2018, 06:37:17 PM »

Side track: I saw this post this morning: https://forum.kitz.co.uk/index.php/topic,14362.msg268409.html#msg268409

Is this me?

In my examination (via Google Street View) of things communications related, close to the Weaving Shed on the Isle of Skye, I saw no evidence of such a jointing post.

Quote
And a beginner's question, just checking my understanding: What exactly is the definition of a DP?

A Distribtuion Point is where the individual circuits to end-users will split off from the multi-pair distribution cable. It could be underground, surface mounted (on a building) or at a pole-top.
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