Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Weaver]

I seem to have lost something like 300-500k d/s sync rate on each of my three lines over the last few months. I wonder why? Could it be something to do with the very long light nights? (It hardly gets really dark at this time of year.) I would have thought that the level of interference picked up on a very long line would be worse at night, the opposite of supporting my hypothesis.

Another theory is that it's something to do with all the new housebuilding in Heasta, so it might either be increased crosstalk due to a greater number of users. Or alternatively, I'm wondering if BT Openreach has done something undesirable to the copper coming into the village and then into my house, which fortunately is the very first one.

[William Grimsley]

I've just been looking at Broadford Exchange and yesterday fibre went live in the exchange but not at the cabinets, according to Telecom Tariffs, so it could be that. But, yes, I'd think that more solar radiation over a 24 hour period could be contributing to more noise.

[aesmith]

I seem to have lost something like 300-500k d/s sync rate on each of my three lines over the last few months. I wonder why?

Have the attenuations changed, or the noise margin?  Or are these still the same but the speed just lower?

[Weaver]

@aesmith: I see the attenuations X have indeed changed, Tony, although I don't have figures going back far enough, not as far back as I would like, because I didn't save the data back in, say, January. But anyway, since the end of May, the d/s attenuation _has_ deteriorated. For example, the slowest line (only slightly slower) has shown an increase from 65.7 to 66.6 dB just over those few weeks.

I think the SNRM has deteriorated by something in the range ~0.5 - ~1.0 dB too (extremely rough figures, guesswork). The d/s target SNRM is set to 3dB, and the links seem to be very stable even at these low SNRMs. But the SNRMs eventually drift down to something in that range, though of course if I remake the link, then the SNRMs will go straight back to 3dB as you would expect. So it seems to me that these numbers aren't wholly meaningful in that they are uptime-dependent.

[Weaver]

Example d/s tx rates - not sync rates, that would be tx_rate / 0.88 (or whatever) - something more like the true L3 PDU throughput. These numbers could be obtained by subtracting the  AAL5 overheads etc from the sync rates, roughly speaking. The numbers are taken from reports from Andrews & Arnold's server "clueless.aa.net.uk".

Notice however that this line has picked up a good bit recently, but is still a fair way down on what it was at the start of the year.

--

 9 Jun 13:07:12    Tx rate changed from 2166192 to 2225286
 9 Jun 01:11:34    Tx rate changed from 2279088 to 2166192
 5 Jun 11:26:48    Tx rate changed from 2272914 to 2279088
25 May 15:11:05    Tx rate changed from 1981854 to 2378754
11 May 13:52:00    Tx rate changed from 1950102 to 1981854
11 May 12:18:36    Tx rate changed from 1904238 to 1950102
11 May 12:02:05    Tx rate changed from 1915704 to 1904238
11 May 11:56:43    Tx rate changed from 1947456 to 1915704
11 May 11:34:53    Tx rate changed from 1960686 to 1947456
11 May 11:30:05    Tx rate changed from 1981854 to 1960686
11 May 11:25:20    Tx rate changed from 1972152 to 1981854
11 May 11:19:31    Tx rate changed from 1957158 to 1972152
11 May 11:14:49    Tx rate changed from 2382282 to 1957158
 9 May 12:59:44    Tx rate changed from 2391102 to 2382282
23 Apr 21:24:12    Tx rate changed from 2503998 to 2391102
 1 Apr 12:06:57    Tx rate changed from 2491650 to 2503998
31 Mar 16:04:23    Tx rate changed from 2463426 to 2491650
30 Mar 15:43:13    Tx rate changed from 2481948 to 2463426
11 Mar 22:33:16    Tx rate changed from 2550744 to 2481948
23 Feb 20:57:32    Tx rate changed from 2466954 to 2550744
16 Feb 22:09:41    Tx rate changed from 2503998 to 2466954
 5 Feb 16:04:41    Tx rate changed from 2457252 to 2503998
 4 Feb 20:58:11    Tx rate changed from 2503998 to 2457252
 2 Feb 04:43:07    Tx rate changed from 2522520 to 2503998
 1 Feb 23:33:07    Tx rate changed from 2513700 to 2522520
 1 Feb 20:15:41    Tx rate changed from 2503998 to 2513700
24 Jan 14:04:14    Tx rate changed from 2566620 to 2503998

[Weaver]

Actually, the penny suddenly drops. If attenuation is changing, then that can't be explained by external environmental factors such as the length of the day=duration of daily period of higher external noise. It surely must be BT Openreach up to no good in the village.

What would they do if they have to add so many pairs for extra new houses that they run out in the current bundle?

[ejs]

My line stats show a very slight increase in attenuation from winter to summer, possibly explained by the change in temperature. 1st Jan this year DS atten was 58.1 dB and US 36.5 dB, today's are 58.5 dB and 36.9 dB. But it may not have been particularly cold then, nor is it that hot now. The lowest the DS atten got down to was 57.7 dB when it was coldest.

So I think attenuation does vary slightly with the temperature, although I'm not sure if that could explain the change over the shorter time frame.

[aesmith]

Those A&A figures are I think their own profile speeds.  I'm not clear what triggers them, although it looks like it might be only when there's a ppp reconnection.   Not sure on that, but they definitely don't happen (for me) at each DSL reconnection.   For example on Friday night I had a disconnect/reconnect at around 1 in the morning, knocking the synch speed down enough for the BRAS profile to drop.   In the morning I did a manual resynch to get a slightly better speed (daytime SNR) and it was only after that manual resynch that the A&A log shows a profile speed change.

Question - is it conceivable that a BT initiated DSL reset (like DLM intervention) doesn't cause a ppp disconnect/reconnect?

Either way I wonder what was happening when you've had several changes within one day.

[Weaver]

they seem to be on a delay timer (lazy) set to some interval after BT reports a profile speed change, from what I'm told anyway.