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Groups > comp.os.linux.misc > #87376

Re: Redundancy/Survival

From TheLastSysop <thelastsysop@dev.null>
Newsgroups comp.os.linux.misc
Subject Re: Redundancy/Survival
Date 2026-06-02 16:36 +0000
Organization The Null Device Restoration Society
Message-ID <a261568aa0a0bd9b6287@dev.null> (permalink)
References (11 earlier) <10vl3kr$2ii0i$1@dont-email.me> <10vmtdr$6c5k$1@solani.org> <71b3fmxhhh.ln2@Telcontar.valinor> <f5c151e204a788607173@dev.null> <10vn00o$32aon$1@dont-email.me>

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>On Tue, 2 Jun 2026 12:22:46 -0400, InterLinked <usenet@phreaknet.org> wrote:
>On 6/2/2026 12:03 PM, TheLastSysop wrote:
>>> On Tue, 2 Jun 2026 17:55:51 +0200, "Carlos E.R." <robin_listas@es.invalid>
>>> wrote:
>>> On 2026-06-02 17:38, Marco Moock wrote:
>>>> Am 02.06.26 um 01:12 schrieb InterLinked:
>>>>> On 6/1/2026 9:40 AM, Rich wrote:
>>>
>>>
>>>
>>>>> My point was that copper POTS customers can get speeds in the 40s/50s
>>>>> calling the same service, no problem at all, but I'm not able to do
>>>>> that with my service being delivered over fiber. Dial-up Internet
>>>>> speeds are actually *hampered* by fiber... how ironic is that?
>>>>
>>>> This is because the analog signal is being converter to a digital signal
>>>> by an analog to digital converter - it does not interpret the digital
>>>> data signal. With ISDN, this was't that faulty, as ISDN is line-
>>>> switched. IP is packet-switched, so jitter is there and relevant.
>>>> The VoIP phone signal is also transferred between different carriers,
>>>> which means there might be codec conversions.
>>>>
>>>> TLDR: V.90 is intended for analog lines, not for any digital service.
>>>
>>> Huh, no, not fully correct.
>>>
>>> V.90 assumes the analog signal from the phone is converted to digital on
>>> the spot, at the client's exchange.
>>
>> Right. The useful distinction is not "copper vs fiber" by itself, but whether
>> the modem path is the old PSTN/PCM path V.90 was designed around. V.90
>> downstream assumes a digital server-side modem and a mostly-digital phone
>> network with one final D/A conversion near the subscriber loop.
>>
>> Once the analog modem signal is created by an ATA/ONT and then packetised as
>> VoIP, all the boring voice-service details start to matter: codec, jitter
>> buffer, packet loss concealment, echo cancellation, VAD, transcoding, and
>> clocking. Even if the access medium is fiber, the modem no longer sees the
>> same
>> sort of path.
>>
>> Practical things I would check, if someone actually needs dialup to work over
>> such a line:
>>
>> * force G.711/u-law or A-law only, with no compression;
>> * disable VAD/silence suppression and echo cancellation if the gear allows
>> it;
>> * give the ATA/ONT traffic decent QoS and avoid WiFi in that path;
>> * try limiting the modem to V.34/33.6 rather than chasing V.90 speeds.
>>
>> If that still does not hold, the annoying answer is that the line is fine for
>> voice but not a transparent modem circuit.
>
>Everyone here seems to be missing the point or did not fully read what I
>said earlier.
>
>I have regulated "POTS over fiber" service and it uses private
>facilities. There is no other traffic on the fiber, it's just voice. I
>can get perfect connections at 33.6k that stay up forever and do not
>drop. Also very good connections with low speeds (300 baud) that
>normally see lots of corruption over VoIP.
>
>Jitter and latency are not the issues here.
>The codec is not the issue here (it's G.711 ulaw, as it should be).
>There is no compression.
>The voice quality is excellent and basically identical to TDM. I have no
>qualms with the quality of my service in general. I just dislike that
>there's no common battery as with copper, and a few other things.
>
>All of these things would be problems with "over the top" VoIP, this is
>not over the top VoIP, it is actually engineered very well. Over the top
>VoIP, you would never get 33.6k connections that stay up forever, or
>long 300 baud modem sessions with no corruption.
>
>I suspect (but have not confirmed) that the ONT is doing something weird
>with V.90 handshakes. It could be as simple as DTMF false detection for
>a signal in the handshake that screws up the V.92 negotiation and causes
>it to fallback to 33.6 - except I know the ONT is configured for inband
>from other stuff I have analyzed with telco techs in the past, so I
>don't think that's it exactly... but maybe you get the idea.
>
>If I had the ability to swap out the ONT or further debug it for issues,
>I'm sure I could make it work, unfortunately I don't have that kind of
>access.

Fair enough; if 33.6 is rock solid and low-speed data is clean, then I would
stop treating it as generic bad VoIP and look specifically at the modem-relay
and line-card behaviour in the ONT/softswitch path.

A useful first split would be to make the modem less ambitious and see exactly
which mode breaks:

* disable V.92 and try V.90 only;
* disable V.90/V.92 and force V.34;
* try with/without V.42/LAPM and compression, just to separate carrier
training from higher-layer negotiation;
* if your modem can report it, log the final modulation, symbol rate, retrains,
BLER, and disconnect reason.

If V.34 is boringly stable but V.90/V.92 fails or falls back differently with
small option changes, that points away from packet jitter and toward some
feature in the access voice equipment: echo canceller, tone detector, gain plan,
clock slip, DTMF/CNG/CED detection, or a vendor's idea of "modem passthrough".

Unfortunately the fix, if that is the case, is probably on the provider side: a
different ONT profile, different voice-port firmware, or a real copper/PCM path.
From the customer side you may only be able to gather enough evidence to make
the ticket land somewhere past first-level support.

-- 
TheLastSysop <thelastsysop@dev.null>
"I survived the great rm -rf / rehearsal and all I got was this .signature."

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Thread

Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 02:21 -0400
  Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-26 08:46 +0200
    Re: Redundancy/Survival Marco Moock <mm@dorfdsl.de> - 2026-05-26 09:49 +0200
      Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 04:47 -0400
      Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-26 11:25 +0200
      Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-05-26 09:53 +0000
    Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 04:38 -0400
      Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-26 11:35 +0200
      Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-05-26 22:09 +0000
        Re: Redundancy/Survival John Ames <commodorejohn@gmail.com> - 2026-05-26 16:17 -0700
          Re: Redundancy/Survival Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-05-27 00:02 +0000
            Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-27 00:11 -0400
              Re: Redundancy/Survival Marco Moock <mm@dorfdsl.de> - 2026-05-28 10:32 +0200
            Re: Redundancy/Survival Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-27 08:41 +0100
              Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-27 11:04 +0200
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 03:31 -0400
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-28 09:18 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-28 13:42 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-28 15:01 +0100
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 21:34 -0400
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-29 11:07 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-29 12:55 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-29 12:14 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-29 13:36 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-29 13:26 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-29 19:36 +0200
                Re: Redundancy/Survival Richard Kettlewell <invalid@invalid.invalid> - 2026-05-29 17:24 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-29 19:37 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-29 19:36 +0100
                Re: Redundancy/Survival Richard Kettlewell <invalid@invalid.invalid> - 2026-05-29 22:34 +0100
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-30 04:29 -0400
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-30 13:09 +0200
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-30 23:29 -0400
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-05-31 21:45 -0400
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 12:15 +0200
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-06-01 18:53 -0400
                Re: Redundancy/Survival Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-06-02 01:46 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-06-02 03:01 -0400
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-02 18:12 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 10:16 +0200
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-02 18:09 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 21:26 +0200
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-06-02 02:58 -0400
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-06-02 11:11 +0100
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-05-29 04:30 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-29 01:34 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 06:36 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-31 00:38 -0400
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-05-31 05:09 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-31 03:10 -0400
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-05-31 07:14 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-06-01 00:49 -0400
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-01 04:57 +0000
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 03:20 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 19:45 +0200
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 18:30 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 22:27 +0200
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 10:49 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 13:16 +0200
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-02 18:35 +0000
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-02 18:21 +0000
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 18:25 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 21:36 +0200
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-06-01 19:00 -0400
                Re: Redundancy/Survival Robert Riches <spamtrap42@jacob21819.net> - 2026-06-02 17:44 +0000
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 17:54 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-29 02:17 -0400
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 03:50 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-06-01 01:07 -0400
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 12:47 +0200
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 17:36 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 22:33 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-06-01 12:26 +0100
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 17:31 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 22:49 +0200
                Re: Redundancy/Survival not@telling.you.invalid (Computer Nerd Kev) - 2026-05-30 09:09 +1000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-30 13:17 +0200
                Re: Redundancy/Survival not@telling.you.invalid (Computer Nerd Kev) - 2026-05-31 07:33 +1000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-31 00:14 -0400
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-31 12:09 +0100
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-06-01 00:51 -0400
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-06-01 12:28 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-31 12:58 +0200
              Re: Redundancy/Survival Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-05-27 20:51 +0000
                Re: Redundancy/Survival John Ames <commodorejohn@gmail.com> - 2026-05-27 14:02 -0700
                Re: Redundancy/Survival not@telling.you.invalid (Computer Nerd Kev) - 2026-05-28 08:54 +1000
                Re: Redundancy/Survival Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-05-28 05:04 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 03:54 -0400
                Re: Redundancy/Survival Andy Burns <usenet@andyburns.uk> - 2026-05-28 09:15 +0100
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 12:29 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-28 13:45 +0200
                Re: Redundancy/Survival Robert Riches <spamtrap42@jacob21819.net> - 2026-05-29 02:50 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-29 01:17 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 06:48 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-30 04:25 -0400
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-30 13:20 +0200
                Re: Redundancy/Survival Robert Riches <spamtrap42@jacob21819.net> - 2026-05-30 14:16 +0000
                Re: Redundancy/Survival Robert Riches <spamtrap42@jacob21819.net> - 2026-05-30 04:00 +0000
          Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 23:41 -0400
            Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-27 14:09 +0100
              Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 03:51 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-28 17:08 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 22:14 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 04:41 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-29 01:53 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 06:32 +0000
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 13:19 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 22:52 +0200
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 13:08 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 22:55 +0200
                Re: Redundancy/Survival Nuno Silva <nunojsilva@invalid.invalid> - 2026-06-02 10:39 +0100
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 13:21 +0200
        Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 22:39 -0400
          Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-27 14:10 +0100
            Re: Redundancy/Survival not@telling.you.invalid (Computer Nerd Kev) - 2026-05-28 09:05 +1000
              Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-28 08:19 +0100
            Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 03:52 -0400
              Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-05-28 09:20 +0100
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-28 20:34 -0400
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-05-28 21:07 -0400
                Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 13:40 +0000
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-06-01 19:12 -0400
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 10:28 +0200
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-06-02 12:15 -0400
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 16:19 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 18:30 +0200
                Re: Redundancy/Survival The Natural Philosopher <tnp@invalid.invalid> - 2026-06-02 18:29 +0100
                Re: Redundancy/Survival Marco Moock <mm@dorfdsl.de> - 2026-06-02 17:38 +0200
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 15:48 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 17:55 +0200
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 16:03 +0000
                Re: Redundancy/Survival InterLinked <usenet@phreaknet.org> - 2026-06-02 12:22 -0400
                Re: Redundancy/Survival TheLastSysop <thelastsysop@dev.null> - 2026-06-02 16:36 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-02 18:39 +0200
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 01:21 +0000
                Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-29 02:08 -0400
                Re: Redundancy/Survival rbowman <bowman@montana.com> - 2026-05-29 06:41 +0000
              Re: Redundancy/Survival Rich <rich@example.invalid> - 2026-06-01 13:23 +0000
                Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-06-01 23:00 +0200
  Re: Redundancy/Survival Marco Moock <mm@dorfdsl.de> - 2026-05-26 09:44 +0200
    Re: Redundancy/Survival c186282 <c186282@nnada.net> - 2026-05-26 04:45 -0400
    Re: Redundancy/Survival "Carlos E.R." <robin_listas@es.invalid> - 2026-05-26 11:38 +0200
  Re: Redundancy/Survival "Worst Case" <fritz@spamexpire-202605.rodent.frell.theremailer.net> - 2026-05-26 17:21 +0200

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