Wed, 14 Sep 88 11:05:34 EDT
From craig@NNSC.NSF.NET Mon Sep 12 09:45:15 1988
> management, for example, seems to have broken both models.
I don't think network management has broken the models --
network management has reminded us that the models are maps, not
strict layering in which only the N+1 and N-1 layer
communicate with the N layer doesn't hold.
Well, this is semantics but I think that if you say that strict
layering doesn't hold and network management is some kind of vertical
layer (I'm putting words in your mouth, but that seems to be the
standard way to kludge network management into the layered approach)
then the layered model is broken. In that case, I'm not sure what
practical value I'm supposed to get out of the seven layer model. If
layers aren't practical, we need another way to talk about the
information that the layered model contains. For example, we might
need the concept of data link, physical media, subnetwork, network,
internetwork, transport, presentation, application, network management
"agent", ... but let's not pretend that this stuff is layered. If a
concentric circle diagram with "tunnels" or some kind of flowchart
diagram or a Case diagram presents the particular concept better let's
move to that instead of carrying on this seven layer idolatry any
longer. Three layers and some tunneling is perfectly OK with me.
Gosh, do I sound like a rabid anti-ISORMist? No way. I agree with
Marshall's comments about what OSI people are doing with the
applications. But when I see significant developments in a >10 year
old transport protocol, I shudder at the thought of the OSI protocols
going through a similar, entirely unnecessary, development cycle.
Kent England, Boston University
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