Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/5/84; site python.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!python!smk
From: smk@python.UUCP (S.Kuzyszyn)
Newsgroups: net.research,net.dcom,net.lan
Subject: Re: ISDN-LAN Gateway Development
Message-ID: <143@python.UUCP>
Date: Mon, 24-Jun-85 07:47:23 EDT
Article-I.D.: python.143
Posted: Mon Jun 24 07:47:23 1985
Date-Received: Tue, 25-Jun-85 07:43:40 EDT
References: <258@dcl-cs.UUCP>, <1499@ecsvax.UUCP>
Organization: Bell Communications Research
Lines: 26
Xref: watmath net.research:182 net.dcom:1053 net.lan:887

ISDN as defined for Basic and Primary access
allows for two general types of connections:
B-channel and D-channel connections.
The B channel is a circuit switched channel
that supports a 64 kb clear channel.
This could be used for packet data between two packet switches
(gateway style).
In this case any protocol
will do (since it is just a bit pipe,
but obviously the protocols should be compatible
at both ends of the pipe).

The other type, a D-channel connection,
supports packet data over
a 16 kb (basic access), or 64 kb (primary access) channel.
Because this D-channle is 
also used for signaling messages
(e.g. for setting up B-channel connections)
the entire capacity is not available for packet data
(in fact, a priority scheme can give
preference
to the signaling messages on the D-channel).

To get to the point, the D-channel will support 
X.25 connections at level 3
and so can be used a gateway.