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Path: utzoo!linus!decvax!bellcore!petrus!mwg
From: mwg@petrus.UUCP (Mark Garrett)
Newsgroups: net.lan
Subject: Re: Bridges, etc. Defined
Message-ID: <30@petrus.UUCP>
Date: Mon, 24-Feb-86 09:14:20 EST
Article-I.D.: petrus.30
Posted: Mon Feb 24 09:14:20 1986
Date-Received: Wed, 26-Feb-86 06:57:55 EST
References: <29500002@siemens.UUCP>
Organization: Bell Communications Research, Inc
Lines: 25

++
> Gateways are devices that connect different network architectures by
> performing protocol translation.  The primary difference between a gateway
> and a bridge is that the gateway utilizes all seven OSI layers where a
> bridge is restricted to layers 1 and 2.

> Frederic W. Brehm       (ihnp4!princeton!siemens!fwb)
> Siemens Research and Technology Laboratories

Do gateways really go to layer 7?  This would imply that a gateway sometimes
needs to know about what specific application is running through the network.
I can't imagine a need to know anything above the session layer.

Also, someone mentioned that a bridge can do protocol conversion between
dissimilar networks.  Perhaps if this conversion is simple (changing one
address for another, and one control code to another syntax with the same
meaning etc) - but if it requires anything like a microprocessor and
software, as opposed to a little finite state machine (ie PAL), I would
call it a gateway.  This isn't any official definition, just what makes
sense to me.

Comments?

Mark Garrett
Bellcore