[cisco-nas] X.75 and modem dial-in, autocommand to TCP

[Gert Doering]

Hi,

a customer of ours currently has a dedicated PABX which is feeding an
ISDN PRI into a bank of about 20 "ISDN modems" (USR Courier I-Modem,
which do X.75 and "V.34 stuff" modem calls).  Modems are connected
to serial terminal servers, which in turn connect to an AIX unix system.

Customer is unhappy, because these take up lots of space, the PABX is
expensive, modems crash and need a reset, USR Courier I-Modems are not
sold "new" anymore, and so on.

So the idea was to build something with a router - PRI channel into
router, "transparent TCP stream" out of the router to the AIX system,
to be handled by a something like telnetd.  We can handle everything on
the AIX side, the questions are on the router side :-)

 - as far as I understand AS5xxx boxes, this should be doable with
   an AS5350 or the like

 - what do I need to terminate X.75 calls?  Do I need modem DSPs, or 
   will the X.75 be handled by the "digital side"?

 - I assume that X.75 calls will end up on a "line async ...", so I can
   put an "autocommand" there, to immediately connect from the router
   to the host at CONNECT time (*no* prompting or any sort of messages
   from the router is permitted).

   Will that work?  It MUST be a) completely 8-bit transparent (Zmodem
   transfers over X.75) and b) completely silent (end user call-up scripts
   get upset if 'yet-unseen' messages show up).

 - is there Cisco gear that can handle X.75 on BRI lines (so we could
   develop and test this on an ISDN S0 port, without disconnecting the 
   whole PABX)?

 - some of the clients have 'issues' with X75 window and block sizes - can
   this be tuned on the Cisco side, as in "we need to have the X75 block
   size set to 4096 byte on reception, 8192 on transmission"?


If Cisco cannot do this - any other gear that's still sold and supported
(important!) that one could use to terminate X.75 and modem calls?

thanks,

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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