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Author Topic: Sync drops by a third  (Read 5764 times)

22over7

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Re: Sync drops by a third
« Reply #15 on: May 02, 2017, 05:45:35 PM »

The BT engineer just left. He was here from 1pm to gone 4:30, up poles, in PCP, head scratching, running several tests.  Noisy copper. Line swap, DLM reset.  Left, saying (1) DS now stable at 67, (2) he'd keep an eye on it as he wasn't 100% happy about where the noise was coming from.  Supernaturally diligent and pleasant guy.  Explained everything he was doing. Can I send Openreach some kind of unsolicited glowing testimonial?  Sadly, I've forgotten already his second name. Ross someone, from Yorkshire.

I started uploading my stats again. At the moment (17:13), my-idea-of-the-basics are:

SNRM                    5.9     / 7.1
DS/US attainable:  79904/22572
DS/US actual:        69594/19999
PWR:                     13.8  / 7.4
ATTN(DS)               18.0
INT                        1363 (??)/ OFF

Of course, TBB speedtests are still hard-clamped at around 40/16. The engineer watched it run, and said it must be Plusnet doing that.

My Plusnet ticket is on hold till tomorrow 9:00am, when I'm away all day, mostly inaccessible.  I think I might add a note (P'net highly discourage this) saying more-or-less
the above, in the hope of triggering whatever administrative thing they have to do to allow me to get the service I'm paying for. Or perhaps I'd better wait for them to get the engineer's report.

 
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burakkucat

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Re: Sync drops by a third
« Reply #16 on: May 02, 2017, 06:09:06 PM »

The BT engineer just left. He was here from 1pm to gone 4:30, up poles, in PCP, head scratching, running several tests.  Noisy copper. Line swap, DLM reset.  Left, saying (1) DS now stable at 67, (2) he'd keep an eye on it as he wasn't 100% happy about where the noise was coming from.  Supernaturally diligent and pleasant guy.  Explained everything he was doing. Can I send Openreach some kind of unsolicited glowing testimonial?  Sadly, I've forgotten already his second name. Ross someone, from Yorkshire.

Yes, certainly.  :)

Please visit this Openreach page, scroll down to the "Let us know how we did" heading and then take the "send them a thank you message" link.
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WWWombat

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Re: Sync drops by a third
« Reply #17 on: May 02, 2017, 06:17:04 PM »

Plusnet might merely need you to stop & start the PPP connection to get the speed limit back. Maybe, but maybe not.

Looking at the graphs, and comparing, I can see
- That the Hlog graph has barely changed with the new line, so both seem to be OK
- The QLN is much better than it has been recently.
- The QLN now if back to being similar to how the old line was at higher frequency - above ADSL2+. In the lower frequencies, ADSL2+ and below, it is getting much LESS noise.

However, while you have synced at a high speed, you are getting a high rate of errors, even though (old-style) FEC and interleaving is turned on. I'd say there was a chance that DLM might even need to turn you onto a higher interleaving setting.

If you have the right modem, it might be worth making changes to set a lower maximum sync speed, to keep the error rate down. Others can guide you on that method.

Are you on a Huawei cab? If so, then the best aim would be to get DLM to change you over to G.INP, which would need you to keep error rates under control.
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22over7

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Re: Sync drops by a third
« Reply #18 on: May 02, 2017, 10:20:54 PM »

I think this got lost (reduced):

to burakkat: thanks much for the engineer big-up link. I hope I did it effectively. Stellar individual.

to WWWombat: thanks advice. To anyone: very grateful for any links and advice about reducing sync speed to avoid new problems now (on HG612/Huawei).

Pi.
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banger

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Re: Sync drops by a third
« Reply #19 on: May 03, 2017, 01:11:20 AM »

I think this got lost (reduced):

to burakkat: thanks much for the engineer big-up link. I hope I did it effectively. Stellar individual.

to WWWombat: thanks advice. To anyone: very grateful for any links and advice about reducing sync speed to avoid new problems now (on HG612/Huawei).

Pi.

There is a sticky post at the top of this forum if you have a read on how to cap speed on the HG612 to reduce sync speed and errors at the same time and it also may reduce your interleaving with less errors thus delay.

I found that G.INP when enabled really gives you a boost in speed and reduces errors alot but if you are not on a Hueawi cabinet its unlikely you will see it.

Edit: I see you are on MDWS and G.INP is not active, you may get full sync with low errors if G.INP kicks in over the next couple of days. At present you are on high interleaving so its wait and see without rebooting the router/modem.
« Last Edit: May 03, 2017, 01:18:30 AM by banger »
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Tim
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22over7

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Problem resolved (for the time being)
« Reply #20 on: May 04, 2017, 03:42:12 PM »

My problem of my broadband speed tests being stuck at 40/16 has gone, though (1) (possibly) Plusnet resetting some-profile-or-other, and (2) (sheepishly) me, some hours later, logging of from Plusnet and then back in again. (At the prompting of a singularly helpful CS help bod in one of their forums.)

A TBB speed test now runs at 74/16.  :)
I do appreciate though that the line is noisy and sync is likely to deteriorate, some.   
 

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WWWombat

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Re: Sync drops by a third
« Reply #21 on: May 04, 2017, 10:17:02 PM »

I can see that G.INP has been turned on, and the error rate has gone down, even with a jump in speed of 10Mbps - banger's prediction was right. Looks OK at the moment, but of course the dreaded crosstalk can cut in at any time...
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22over7

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Re: Sync drops by a third
« Reply #22 on: August 09, 2017, 07:26:43 AM »

I doubt it is of general interest, but I have been experimenting with capping my sync rates on my modem. 

It is (to me) a dark art, but it seems to work!   After DLM reset, my line went to "INT 8" after a short while, then "INT 16" after a longer while.  I was able to pull it back to "INT 8" with a downstream cap of 72Mb/s and upstream of 16Mb/s (at least I think that is what did it). With these caps I get speed-tests of about 66Mbps and 13Mbps. My attainable is roughly 89/22. 

There's quite a difference in responsiveness between "INT 16" and "INT 8"; its only when downloading an operating-system or a movie that throughput matters, and then only a little.

Could I get rid of "INT 8" by setting my sync-caps even lower?

What are the relative effects of upstream and downstream caps?  I do copy a few 10's of MB up sometimes, but the time
it takes is seconds at most.

What might happen if I left the down sync cap at 72, and lowered the up to 10? 
(Most errored seconds on my line seem to relate to the upstream.)
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Dray

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Re: Sync drops by a third
« Reply #23 on: August 09, 2017, 08:28:15 AM »

Probably because there is no G.inp on the upstream
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tbailey2

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Re: Sync drops by a third
« Reply #24 on: August 09, 2017, 08:55:26 AM »

Wrong. There are at least eight active users on MDWS with G.INP set on the upstream...
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Tony
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Dray

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Re: Sync drops by a third
« Reply #25 on: August 09, 2017, 08:59:42 AM »

That sounds interesting. When I got G.inp on upstream it was because something was failing inthe cabinet resulting in huge instability which G.inp coped very well with
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ejs

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Re: Sync drops by a third
« Reply #26 on: August 09, 2017, 09:01:54 PM »

There's quite a difference in responsiveness between "INT 16" and "INT 8"; its only when downloading an operating-system or a movie that throughput matters, and then only a little.

There really shouldn't be, because the interleaving depth is really not a significant value. The interleaving delay will be the same, and the interleaving depth tends to vary according to how much data can be shuffled up in the interleaving delay interval. So when you have less bandwidth, there'll be less data in the same time interval.

With G.INP though, the interleaving depth is the size of the DTU (the smallest chunk of data that can be retransmitted). By capping the rate, you've decreased the size of the DTU, and the change in interleaving depth is secondary to that.
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Chrysalis

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Re: Sync drops by a third
« Reply #27 on: August 09, 2017, 09:23:13 PM »

yeah latency is usually more important than overall speed.  Which is why I consider banding preferable to interleaving, but there is an obsession of speed by a lot of people. :)
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22over7

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Re: Sync drops by a third
« Reply #28 on: August 21, 2017, 09:27:23 PM »

It's maybe interesting to see what a difference sync-capping makes, by looking at what happens to a BQM when one forgets to apply it, on installing a new modem.
https://www.thinkbroadband.com/broadband/monitoring/quality/share/6bcea9e0ffe0448345d6001ae25d4cf44662bc80-21-08-2017
My errored seconds at (80/20 uncapped) went through the roof for a day, latency was horrible, and speed tests weren't great.

The second red band is me setting
caps back on (in my 30 mins offline), and having the bright idea of turning wan pings off -- till I remembered an hour later that's how TBB's BQM works.

BTW, the new modem is a VMG132-B10D; old was HG612. It's nice to be able to ssh in without weird flags. At least.
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banger

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Re: Sync drops by a third
« Reply #29 on: August 21, 2017, 09:58:55 PM »

Are you on MWDS? If so what username?
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Tim
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