S-x86; You too can make your internal modem run PPP with asppp !!!

[swedel@tymnet.com (Scott Wedel)]

Sun Folks,
This is a reoccuring problem that really deserves a FAQ.  It is well
enough written that it is already nearly good enough to be a FAQ.  I
have taken the great liberty to add a header to the explanatory sections.
I removed what appears to be extraneous stuff (putting the STTY stuff
early and the changes to the Systems file since there is no harm if it
retains the P_ZERO "" command).  At the very least this should show up
quickly if someone searches the mail list archive.

------------------------------------------------------------

PPP internal modem FAQ

SYNOPSIS:  Problems with PPP and internal modems
OS:     Solaris

The symptom is that tip and cu appear to work fine, but ppp fails
miserably.  The asppp.log file (with debug enabled) might report numerous
BAD FCS errors in the input stream.  Another possible symptom is the modem
initialization times out and fails.

The solution is that the P_ZERO must be the first thing in the
Dialers script.  They must appear before the first AT command is sent
to the modem.  All of the documentation I have seen says to put the
P_ZERO in the beginning of the Systems file entry after the modem has
autosensed the input characteristics of the serial port which is too
late.  This doesn't appear to be a problem with external modems where
the UART is a physically independent device.

Here are what the Dialers entries should look like for a SUPRA 56K modem

/etc/uucp/Dialers Entry:
# note the P_ZERO "" before sending anything to internal modem
internalsupra  =,-, ""     P_ZERO "" STTY=crtscts,crtsxoff ""
\dA\pTZ&F0&D0E1V1W1Q0L0S2=255S10=254S9=12S41=131S42=131S109=62T\r\c OK\r
\EATDT\T\r\c CONNECT

------------------------------------------------------------
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> From: george@palisad.com
> Date: Wed, 6 May 1998 20:06:36 PDT
> Message-Id: <199805070306.AA06392@palisad.com>
> To: solaris-x86@webpro.eis.com
> Subject: S-x86; You too can make your internal modem run PPP with asppp !!!
> Sender: owner-solaris-x86@webpro.eis.com
> Precedence: bulk
> Reply-To: george@palisad.com
> X-Mailinglist: solaris-x86
> Status: R
>
> PPP-ers,
>
>     After much trial and error, I finally figured how to get internal
> modems to work under Solaris.  It turns out that if you follow the
> instructions (answerbook and FAQ's), ppp will work fine for an external
> modem, but internal modems (at least 2 that I have tried so far) will fail.
> I have only tried 56K modems (Best Data and Diamond), and don't know if
> this is also a problem with slower modems or other modem vendors, although
> I suspect it is since I see references to the symptoms long before 56K
> modems existed.
>
>     The symptom is that tip and cu appear to work fine, but ppp connects
> and logs in and subsequently fails miserably.  The asppp.log file (with
> debug enabled) reports numerous BAD FCS errors in the input stream.  I saw
> this symptom mentioned in many places in the digests, but never came across
> an asppp based solution.  The only solutions seemed to involve external
> modems or pppd.  Since I am running Solaris 2.6, and pppd is reported not
> to work yet for 2.6, and the only external modems I have are 28K, I was
> forced to find a solution.
>
>     The solution is that the P_ZERO and/or STTY pseudo expect/send pairs
> must be the first thing in the Dialers script.  They must appear before the
> first AT command is sent to the modem.  All of the documentation I have
> seen says to put the P_ZERO in the beginning of the Systems file entry and
> put the STTY at the end of the Dialers entry.  In both cases, these are
> executed, after the modem has autosensed the input characteristics of the
> serial port.  Apparently, if these are changed after the autosense, the
> UART on the modem card gets into some funny state.  It appears to be some
> kind of parity problem or other problem with the most significant bit,
> since the cause of all of the BAD FCS errors is always an upper bit being
> set when it shouldn't be.  This doesn't appear to be a problem with
> external modems where the UART is a physically independent device.
>
>     Here are what the Systems and Dialers entries should look like for a
> SUPRA 56K modem (you should be able to figure out the Devices entry).  Note
> that your chat scripts might be different (i.e. --gin: instead of --name:).
>
> Systems entry:
>
> ppphost Any ACU 115200 5551212 "" \n name:--name: pppuser word: PpPpAsSwD
>
>
> Dialers Entry:
>
> supra  =,-, ""     P_ZERO "" STTY=crtscts,crtsxoff ""
> \dA\pTZ&F0&D0E1V1W1Q0L0S2=255S10=254S9=12S41=131S42=131S109=62T\r\c OK\r
> \EATDT\T\r\c CONNECT
>
>     Some of the S register settings are undocumented in the SUPRA 56K
> manual and probably are not that important, although it does seem to work.
> These were actually taken from the setup for an older, 28K SUPRA FAX modem.
>
>     Someone should probably integrate this info with the appropriate FAQ's.
>
> George White
> george@palisad.com
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