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From: prc@erbe.se (Robert Claeson)
Newsgroups: comp.dcom.lans
Subject: What services does X.25 provide?
Keywords: x.25, services, login, e-mail, file transfer, IPC
Message-ID: <796@maxim.erbe.se>
Date: 7 Sep 89 15:52:46 GMT
Reply-To: prc@erbe.se (Robert Claeson)
Organization: ERBE DATA AB, Sweden
Lines: 19

I'm completely new to X.25, and need to know more about it. I've been
able to get enough information to know that X.25 has three layers,
of which the top-most handles the addressing. What I haven't been
able to get into my poor head is the difference between X.3, X.28 and
X.29, and what services an X.25-based network provides. For example,
does X.25 only define raw circuits, or are there multiple types of
circuits (for, say, e-mail, remote login and file transfer)? I can
almost guess that X.400 is the X.25 so-called application-layer
protocol for e-mail. I believe that the combination X.3/X.28/X.29
does the same for remote login, but does it define a virtual terminal
like ISO VT, or is is more like rlogin over TCP/IP? In other words,
do I still need a 3270 emulator for my VT220 to use X.25 to connect to
an IBM mainframe with an X.25 interface?

Please enlighten me, if you think that you can.

-- 
          Robert Claeson      E-mail: rclaeson@erbe.se
	  ERBE DATA AB