Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: 1 2 [3] 4

Author Topic: Fastest ever downstream performance  (Read 2345 times)

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 18769
  • Over the Rainbow
    • The ELRepo Project
Re: Fastest ever downstream performance
« Reply #30 on: January 27, 2017, 04:45:26 PM »

I'm really just thinking out loud . . .

Weaver has three lines, thus three modems in office. There are 24 hours per day.

So how about an automated process that re-boots just one of the three modems every eight hours, in a cyclic sequence. Hence after the elapse of 24 hours, all three of the modems will have been re-booted.  :-\

Of course I could just be caterwauling from the top of the pole, from which the drop-cable, that serves The Cattery, is connected.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

aesmith

  • Reg Member
  • ***
  • Posts: 645
Re: Fastest ever downstream performance
« Reply #31 on: January 28, 2017, 08:19:54 PM »

But if the low SNR isn't causing a problem, why bother?  If it continues to drop, day by day, then one night it will drop and reconnect of it's own accord.  On the other hand for example my router seems to show reducing SNR for a day or so after a re-synch but then remains stable.
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 18769
  • Over the Rainbow
    • The ELRepo Project
Re: Fastest ever downstream performance
« Reply #32 on: January 28, 2017, 09:41:02 PM »

Indeed.  :)

Just caterwauling by me.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #33 on: January 29, 2017, 01:15:41 AM »

The question, unresolved still, is how badly does the modem perform when the SNRM gets ridiculously low - should it perhaps give up sooner because it is delivering corrupt data all over the place? Rebooting modems would make a difference in that case.
Logged

aesmith

  • Reg Member
  • ***
  • Posts: 645
Re: Fastest ever downstream performance
« Reply #34 on: January 29, 2017, 09:34:51 AM »

Depends on why the SRNM is low.  If it's low because of increased noise and/or reduced signal strength due to temperature, RF propagation etc then re-synch would be at a lower speed/higher margin.   If it's low because of bit swapping dropping tones and not reclaiming, then resynch would probably be at the same speed but higher margin (this is what mine shows).

As for what harm it does, I believe modem should drop and attempt reconnection at some rate (maybe should be 0dB, but I've seen them go negative).  Other than that it may cause higher error rates.    Since you can't get real time stats from your modems at the moment, you could try grabbing a couple of snapshots from Clueless, one just over 15 minutes after re-synch and one at some later time when the margin's really low.
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 18769
  • Over the Rainbow
    • The ELRepo Project
Re: Fastest ever downstream performance
« Reply #35 on: January 29, 2017, 04:07:22 PM »

. . . (maybe should be 0dB, but I've seen them go negative).

I, likewise, have made such an observation with an HG612. It "held on" right down to -1.9 dB, only "letting go" at -2.0 dB.
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #36 on: January 30, 2017, 01:56:30 AM »

I have seen Netgear DG834 modem/routers read a huge value which I presumed was a bug in the ascii decimal string conversion when the numbers go negative. It got fixed by a later update. They were famously happy to hang on at around zero dB.

This perhaps should be a configurable option in modems - minimum SNRM, plus hang on or give up: possibly conditional on actual recent error rate, and with an option to only resync if absolutely necessary or if below some SNRM threshold and / or above some recent error rate - as before - IF the link has been idle for x seconds recently, or within some time-window based on time of day. Those latter conditions would minimise the likely annoyance / impact of the downtime during reconnection.
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #37 on: January 30, 2017, 01:56:46 AM »

line4

Does anyone know how long it takes BT to adjust their BRAS d/s rate on 21CN? When I was on 20CN, I used to refer to kitz' delay time table for guidance about the time - in the order of days rather than hours - it takes for BT to catch up following a d/s sync rate change, but I don't know what the timing is supposed to be like now I am on 21CN.

Most recent numbers for line 4 below. Showing the new absolutely all-time high sync rate of 2902, never seen anything in the 29xx range before.

BT Test xDSL Status Check:Pass Standalone sub test passed successfully.Pass OK. Circuit In Sync
BRAS=2319kb/s FTR=2278kb/s MSR=2848kb/s ServOpt=1 I/L=A
A SERVICE OPTION CHANGE ORDER IS IN PROGRESS ON THIS LINE
Up Sync=426kb/s LoopLoss=41.9dB SNR=5.9dB ErrSec=0 HECErr=0 Cells=0
Down Sync=2902kb/s LoopLoss=65.1dB SNR=1.5dB ErrSec=0 HECErr=N/A Cells=0

The bras d/s rate of 2319 seems too low to me, it hasn't adjusted yet to the recent increase in d/s sync due to me going back to 3 dB d/s target SNRM at the end of the brief experiment of running on a supposed 6dB to see what difference that might make. (The 6dB experiment was unsuccessful. The modems just are not following the target and the actual SNRM doesn't in fact go up - it is low straight after a reboot, as far as I can see.)

The most recent quoted AA TX rate shown in the clueless log 2551626, which would mean that BTW is in control, not AA, one reason why the VoIP is possibly not going to work especially if you don't run at AA's suggested VoIP-friendly reduced rate of 95% (*). I suppose I will have to wait for BT to change their ideas on d/s rate and then they can report that to AA in turn. So, at the moment, I presume that a certain amount of traffic is crossing AA's network unnecessarily, only to get dropped by BT anyway.

--
(*) I use AA's phone service, but I couldn't get VoIP to work reliably, and nowadays can't get my Siemens Gigaset N300 VoIP box to work at all in any case, so I am using AA -> mobile phone inbound call redirection, which works brilliantly.
Logged

aesmith

  • Reg Member
  • ***
  • Posts: 645
Re: Fastest ever downstream performance
« Reply #38 on: January 30, 2017, 02:58:28 PM »

Just by the way I was searching for something else, and came across an older post from when I think you were on 20CN.   If that's the case then it seems that the aggressive, low SNR behaviour of the D-Links applies on 21CN but not 20CN.   You were reporting a lower sync speed as well, below 2272.

I'm on a TI DSLAM, and my target SNRM is the usual 6dB, with the DLinks, the SNRM doesn't tend to drop much below that.
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #39 on: January 30, 2017, 10:10:49 PM »

Thing is, 3dB d/s SNRM target was not available on 20CN on my BTW line. Before I was upgraded to 21CN, the DSLAM was first upgraded, which produced a sizeable speed improvement, then I got ADSL2 which gave further improvement, and then I chose to switch from 6dB to 3dB.

The modems were well-behaved back then. Perhaps it is all down to this business of tones ending up at zero bits after a (short) period of change. And perhaps it is because I am starting off at only 3dB anyway that helps me get down to zero bits. Actually, more like, perhaps the fact that in ADSL2 single-bit tones are allowed, which they were not when I was on ADSL1, makes it very easy to get to zero bits. Perhaps I would be more stable under ADSL1.

But it's speed speed speed that I am after, and as long as stability is bearable I don't care too much as the three lines give me a lot more insurance compare with the usual situation. As long as I am engaged in normal non-performance-critical usage such as ordinary TCP, I don't even notice a line going down briefly. Mind you, on Sunday morning I lost a line for five minutes or so (rather too long?) and that reduction in total throughput completely stuffed up the Apple TV 4 box which was doing 'real time' live streaming, not a best-effort download. (Haven't worked out how to do downloads directly on to the Apple TV 4 itself. Can do Apple downloads to the iPad and send it to the Apple TV though.)
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #40 on: February 01, 2017, 06:46:49 AM »

And now we have another all-time high result from speedof.me

 d/s  /  u/s Mbps  - server: London 2
7.81 / 0.91 * new d/s record
7.57 / 0.92
7.76 / 0.93

The BRAS rates are currently:
    line 1: 2475k, line 3: 2521k, line 4: 2560k - total 7556.

The most recently reported AA Tx rates I can find are
    line 1: 2466954, line 3: 2512828, line 4: 2551626 - total 7531408 (= ~99.7% of the BRAS total)

So I calculate that speedof.me is reading 3.7% higher than the AA Tx rate. So this is a small amount of exaggeration by speedof.me, especially since presumably the AA TX rate can't be including all the PPPoE+ethernet crap that is going between my modems and the BRAS, which means that my side of the link to the BRAS is handling more data than AA are seeing, not the other way around, and the total bytes a speedtester can count should be less, not more.
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #41 on: February 01, 2017, 08:53:57 AM »

I've just realised that if speedof.me is to be believed at all, a big if, then that would indicate that the IP-bonding of the lines into one pipe is efficient in the downstream direction.

Upstream is not so good though, as my figures suggest that I have roughly a 20% performance loss somewhere, and that is even after taking out protocol overheads, if I believe in speedof.me rates and compare that with predictions based on upstream throughput derived from sync rate. I should be seeing around 1.2 Mbps but I get a speedof.me rating of 0.9 - 1.0.
Logged

aesmith

  • Reg Member
  • ***
  • Posts: 645
Re: Fastest ever downstream performance
« Reply #42 on: February 01, 2017, 04:56:11 PM »

The modems were well-behaved back then. Perhaps it is all down to this business of tones ending up at zero bits after a (short) period of change. And perhaps it is because I am starting off at only 3dB anyway that helps me get down to zero bits. Actually, more like, perhaps the fact that in ADSL2 single-bit tones are allowed, which they were not when I was on ADSL1, makes it very easy to get to zero bits. Perhaps I would be more stable under ADSL1.
Is the issue with zero bit tones that the router will never reuse them once they reach zero?  If so that explains the way mine shows reduced SNR after the first evening, which isn't recovered until a re-synch.  For reference see tones around 4 hours after re-synch, then after 8 hours then 48 hours later.

« Last Edit: February 01, 2017, 05:02:39 PM by aesmith »
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #43 on: February 02, 2017, 08:40:29 PM »

This phenomenon of ever decreasing snrm, is not good. Perhaps we need a much better modem. I never knew about this. It is an extremely important tick-list item on the shopping list for modems.
Logged

Weaver

  • Kitizen
  • ****
  • Posts: 4004
  • Retd sw dev; A&A; 3 7km ADSL2; IPv6; Firebrick
Re: Fastest ever downstream performance
« Reply #44 on: February 02, 2017, 08:43:45 PM »

And aesmith will be (very slightly) less vulnerable to this badness than I am, because I may have some 1-bit tones on day zero, whereas he, being G.992.1 iirc, will have a minimum of 2, so less close to zero.
Logged
Pages: 1 2 [3] 4
 

anything