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From: jwb@cit5.cit.oz (Jim Breen)
Newsgroups: comp.dcom.telecom
Subject: Re: ISDN and TCP/IP
Message-ID: <2023@accuvax.nwu.edu>
Date: 11 Dec 89 03:04:17 GMT
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X-Telecom-Digest: Volume 9, Issue 566, message 10 of 10

In article <1842@accuvax.nwu.edu>, WEBER@harvarda.bitnet asks:
  
> 1. How do we create a gateway between ISDN and TCP/IP so that
> the following common cases can get access to TCP (and the world):
  
>    a. Dumb terminals with an rs232 connection to circuit switched
>       d or b channels (i.e., 9.6 kbs or 64kbs).
  
>    b. Intelligent peronal computers such as msdos and macintosh
>       machines. These machines would ordinarily have ethernet
>       cards and run something like FTP Software's TCP implementation,
>       or NCSA Telnet on the macs. There might be a stray Unix box
>       somewhere (no one wants to run slip). THe ISDN connection is
>       BRI, not PRI.
  
>    c. Local area networks in buildings which are nt yet connected
>       to the fiber ethernet network. These networks are typically
>       Appletalk or TCP/IP itself, with a few Novell networks
>       here and there. Again, the ISDN connection is BRI, not
>       PRI.
  
This is a question which comes up again and again, so it certainly
deserves some considered attention. We are in a similar position with
a backbone using ethernet and routers, and with ISDN compatible
PABX's. We intend to make almost NO use of ISDN internally. We will be
deriving B-channels for some of our intercampus traffic, and running
them between routers, i.e.  TCP/IP will be there at layers 3 & 4 but
we don't have an interface problem because our (Plessey) digital
handsets provide a standard X.21 64kbps interface.

What you need to solve your problems are some ISDN Terminal Adaptors
(TA) of various flavors. The problem is they haven't been developed
yet! In (a) above you need a pair of asynch TA's, i.e.  TA's which map
various asynch speeds onto a 64k channel, enabling access to some sort
of terminal server. In (b) we all hope there is a PC card coming which
speaks BRI. Of course you need to connect somewhere, so it might be
slip after all. For (c) a TA which can bridge ethernet segments would
be fine.

Clearly there is a long way to go with data access to ISDN, and there
is room for a lot of innovative product development. Start shouting at
your suppliers NOW. Better still, get some designers and builders
together with a venture capitalist and go for it.
 
        _______           Jim Breen (jwb@cit5.cit.oz) Department of Robotics &
       /o\----\\     \O      Digital Technology. Chisholm Inst. of Technology
      /RDT\   /|\   \/|   -:O____/         PO Box 197 Caulfield East 3145
     O-----O        _/_\    /\ /\          (p) 03-573 2552 (fax) 572 1298