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Path: utzoo!mnetor!seismo!munnari!kre
From: kre@munnari.oz (Robert Elz)
Newsgroups: comp.dcom.lans
Subject: Re: OSI-model software
Message-ID: <1707@munnari.oz>
Date: Fri, 19-Jun-87 05:46:38 EDT
Article-I.D.: munnari.1707
Posted: Fri Jun 19 05:46:38 1987
Date-Received: Mon, 22-Jun-87 01:33:57 EDT
References: <1204@botter.cs.vu.nl> <1680@munnari.oz> <192@ditmela.OZ> <943@bloom-beacon.MIT.EDU>
Organization: Comp Sci, Melbourne Uni, Australia
Lines: 26
Keywords: osi, iso, internetworking

In article <943@bloom-beacon.MIT.EDU>, martillo@athena.mit.edu (Yakim Martillo)
writes:
> ... X.25 level 3 has a flow control window.  Anyone who
> has tried to run kermit over a PSPDN knows how well all the
> transmission windows interact.

Huh?  I always thought that the problem with kermit over
x.25 nets is precisely because kermit doesn't have a windowing
flow control scheme (or it has the terminal case, of a window
size of 1).

That is, kermit sends a packet, then waits for an ack.

Packet turnaround in x.25 networks is typically fairly slow,
but this is neither a problem with x.25, nor with the windowing
scheme (which is effectively a no-op when protocols like
traditional kermit are used above it).  Rather, its a problem
with the comparatively low capacity technology used to implement
the networks.

I doubt I'm alone in this belief, as I gather that the kermit
people are defining a new protocol (extended protocol) with
windowing in it, precisely so it will work *better* over x.25
type networks.

kre