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Author Topic: ZyXEL remote resynch command and a crazy internal DLM process  (Read 1386 times)

Weaver

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Two things. Firstly, I am yet again trying to write iPad programs to remote control my ZyXEL VMG1312-B10A modems somehow using the iOS ‘Shortcuts’ programming system. I don’t seem to have a telnet api in Shortcuts, but if there were another easy telnet function that could be indirectly invoked somehow then that would be an answer. I do have an http api in Shortcuts though and I have already been able to successfully drive the ‘easy stats’ http interface provided in my Kitizen Johnson custom firmware modems in order to query the modems for info such as sync speeds without having to log in (as it’s a safe read-only-like api).

I would like to be able to remotely issue an adsl connection --up command, maybe by http if that’s even possible, and be able to automate it. Anyway, something to force a resync. I would also like to be able to force a resync at a particular minimum target SNRM if that’s possible. Given the stupid limitations of the tools that I happen to have available to me on the iPad, it might be that I would need some assistance within the modem to get it to help to make that command accessible by http, since http is about all I have (programmatically, that is) at the moment.

Secondly, I am exploring some very vague ill-formed ideas about doing some kind of DLM for my crazy line #3 with its varying upstream attenuation problem. The idea is that if the upstream SNRM drops below a certain level then I’m considering forcing a resync to get the upstream SNRM up to a safe minimum.

Perhaps the would be the way to go would not to try to remote control the modem to sort things out, although an easy remote ‘resync now’ command would be very useful, but rather to put a DLM service process/daemon into the modem itself and order it to monitor its own upstream SNRM and resync if necessary. To be safe there would have to be a state machine with timers and so forth so that rather than simply forcing a resync, the system would have to ‘ask for one’ which would involve checking guard time intervals so that there would be an enforced minimum time interval between such SNRM-triggered resyncs and ensure some kind of sanity.

I have absolutely no idea about how to require a target upstream SNRM though.
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burakkucat

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #1 on: April 05, 2019, 01:07:32 AM »

As I could not remember all the various Broadcom xdslctl sub-commands available from the CLI, I asked my VMG1312-B10A for help.

Code: [Select]
> xdslctl --help
Usage: xdslctl start [--up] <configure command options>
       xdslctl stop
       xdslctl connection [--up] [--down] [--loopback] [--reverb]
           [--medley] [--noretrain] [--L3] [--diagmode] [--L0]
           [--tones <r1-r2,r3-r4,...>] [--normal] [--freezeReverb] [--freezeMedley]
       xdslctl configure/configure1 [--mod <a|d|l|t|2|p|e|m|M3|M5|v>] [--lpair <(i)nner|(o)uter>]
           [--trellis <on|off>] [--snr <snrQ4>] [--bitswap <on|off>] [--sesdrop <on|off>]
           [--sra <on|off>] [--CoMinMgn <on|off>] [--i24k <on|off>] [--phyReXmt <0xBitMap-UsDs>]
           [--Ginp <0xBitMap-UsDs>] [--TpsTc <0xBitMap-AvPvAaPa>] [--monitorTone <on|off>]
           [--profile <0x00 - 0xFF>|<"8a |8b |8c |8d |12a |12b |17a |30a">] [--us0 <on|off>]
           [--dynamicD <on|off>] [--dynamicF <on|off>] [--SOS <on|off>] [--maxDataRate <maxDsDataRateKbps maxUsDataRateKbps maxAggrDataRateKbps>]
           [--forceJ43 <on|off>] [--toggleJ43B43 <on|off>]
       xdslctl bert [--start <#seconds>] [--stop] [--show]
       xdslctl afelb [--time <sec>] [--tones] [--signal <1/2/8>]
       xdslctl qlnmntr [--time <sec>] [--freq <msec>]
       xdslctl inm [--start <INMIATO> <INMIATS><INMCC><INM_INPEQ_MODE><INM_INPEQ_FORMAT>] [--show]
       xdslctl snrclamp [--shape <shapeId>] [--bpshape [bpIndex-bpLevel,]]
       xdslctl nlnm [--show ] [--setThld <Thld_Num_Tones>]
       xdslctl diag [--logstart <nBytes>] [--logpause] [--logstop] [--loguntilbufferfull <nBytes>] [--loguntilretrain <nBytes>] [--dumpBuf <sizeKb>]
       xdslctl ntr [--start [output freq(default is 8000)]] [--stop]
       xdslctl info [--state] [--show] [--stats] [--SNR] [--QLN] [--Hlog] [--Hlin] [--HlinS] [--Bits]
           [--pbParams] [--linediag] [--linediag1] [--reset] [--vendor] [--cfg] [--webstats]
       xdslctl profile [--show] [--save] [--restore]
       xdslctl --version
       xdslctl --help
 >

After reviewing the above, I realised that so much is uncertain and is really worthy of a separate thread in which we all could speculate on the various sub-commands --
  • bert -- bit error rate test
  • afelb -- analogue front-end loop-back
  • qlnmntr -- quiet line noise monitor
  • snrclamp -- signal to noise ratio clamp
Back on topic, I can't see anything in the above which would aid your quest.
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Weaver

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #2 on: April 05, 2019, 03:27:49 AM »

snrclamp looks interesting.   ???
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kitz

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #3 on: April 05, 2019, 11:11:37 PM »

I realised that so much is uncertain and is really worthy of a separate thread in which we all could speculate on the various sub-commands --

Notes on the xdslcmd in Broadcom based modems?
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Weaver

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #4 on: April 06, 2019, 09:49:51 AM »

Thanks to kitz for that wonderful link concerning modem’s commands plus descriptions of stats. Has a good explicit piece about the definitions of counter values too.
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Weaver

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #5 on: April 08, 2019, 07:34:43 PM »

I’m wondering if I could put something into the modem itself to watch the upstream attenuation figure. When the modem goes into evil half of the day, then that attenuation jumps up by 8dB. So that figure could tell a daemon what is going on and help make sure it makes the right decisions. Then if the upstream SNRM is unhealthy, low, then it could force a resync. There would need to be timers and minimum time duration guards to prevent mad repeated resyncing in some nutty unlikely condition or other.

It’s a shame that there doesn’t seem to be any way of doing upstream sync rate tweaking - is that correct?

I don’t know if it would be worth taking a more refined approach. If the u/s SNRM is low, then we could monitor the CRC fail errors recently, say in the last 15 mins, and prev 15 mins or even record the figures ourselves accumulate them and get a total for the most recent hour but excluding events around any resync (somehow?). The peri-resync exclusion thing would be awkward because if the case of spontaneous link drops. Could get the up-time and then start accumulating CRCs so many minutes after the link comes back up again, and we could work out when that was by working back from the up time.

If there are too many u/s CRC fails then we resynch if various guard conditions hold.
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burakkucat

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #6 on: April 08, 2019, 09:37:24 PM »

. . . then that attenuation jumps up by 8dB.

That should not be happening. Changes or jumps in attenuation are indicative of one or more faults in the relevant metallic pathway.

Quote
It’s a shame that there doesn’t seem to be any way of doing upstream sync rate SNRM tweaking - is that correct?

Correct. I do not know of any CPE that allows the US SNRM to be tweaked.
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Weaver

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #7 on: April 10, 2019, 12:42:54 AM »

Regarding the us 8db attn jumps, this started around November. If memory serves I discussed it with AA who seemed to think that AA would not succeed in trying to make BTW/OR accept that this was something that they had to fix. But you would hope that upstream needs to work properly just as much as downstream does. Perhaps a part of a residential-only mindset assumed for BTW/OR? It’s difficult in this case because is it BTW whom AA needs to moan st, because it is they who supply ‘broadband’ -ie an internet access service - to AA who resells it to the end-user, rather than OR selling something direct to AA? Perhaps I should try again?

The cycle is clearly seen but indirectly in the form of the the daily cycle in u/s SNRM shown in the output of the johnson-easy-web-stats B10-internal data logging and http-based graphing and reporting process. The real trouble is evident if I am unlucky enough to happen to resynch during the low-attenuation ‘good’ part of the cycle, establishing a fast sync speed and then later the link changes to the high attenuation bad condition, so then the current u/s SNRM is only ~2dB for the rest of the day which is not enough for reliable upstream (not without L2 retx available, and it is not available on upstream).
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burakkucat

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #8 on: April 10, 2019, 01:13:02 AM »

Ah, yes. Now that I have read the synopsis you have just provided, I can recall the evident problem with that line (circuit).

As for SNRM tweaking, it is the CO end (DSLAM/MSAN) that can tweak your US -- the mirror image of the CPE end (ZyXEL VMG1312-B10A) which can tweak your DS. (Hopefully I've got that right.)
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Weaver

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #9 on: April 10, 2019, 01:43:39 AM »

Thank you.  ;D It hopefully makes a bit more sense now.
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Chrysalis

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Re: ZyXEL remote resynch command and a crazy internal DLM process
« Reply #10 on: April 12, 2019, 11:52:26 AM »

Quote
The real trouble is evident if I am unlucky enough to happen to resynch during the low-attenuation ‘good’ part of the cycle, establishing a fast sync speed and then later the link changes to the high attenuation bad condition, so then the current u/s SNRM is only ~2dB for the rest of the day which is not enough for reliable upstream

Brings back bad memories of my ADSL days before I had SRA, that is the prime sort of condition that SRA mitigates, if only openreach supported SRA. :(

I had all sorts of unstable SNRM issues, including sudden large dips and jumps from noise bursts, and SRA was able to deal with all of them giving me uptime's of over a year when before SRA I typically resynced 2-3 times a day to maintain stability.

Found some old graphs on my webspace showing some of what SRA was doing, note this was on the 7402NX tho which was buggy on the ukonline dslams, SRA is very picky, this modem had the same chipset as ukonline but a newer version and that was enough for it to break, it worked flawless on the older 7402R2 tho.

SRA

here is 3 graphs from the 7402R2, notice the steady SNRM, but variable sync speed.

7402 Speed
7402R2 SNRM
7402R2 Attenuation
« Last Edit: April 12, 2019, 12:09:20 PM by Chrysalis »
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