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Re: NATmakes a networik a host -- must every process have an IP address?

From: Keith Moore <moore@cs.utk.edu>
Date: Thu, 05 Dec 2002 19:10:57 -0500
Message-Id: <200212060010.gB60Avj28840@astro.cs.utk.edu>
To: Dave Crocker <dcrocker@brandenburg.com>
cc: Graham Klyne <GK@Ninebynine.org>, Tony Hansen <tony@att.com>, discuss@apps.ietf.org

> A host consumes a single address and provides access to a collection
> of processes.  Clients and servers.

The world of processes that access the nework cannot conviently be
divided up into clients and servers.
> A NAT does the same thing.  In terms of "inconvenience" such as for
> providing servers, the problem with NATs is administering address/port
> assignments, rather than there being a core problem with the idea of a
> NAT.

One problem with applying this idea to the vast majority of NATs is
that we put ordinary self-contained hosts behind them and expect 
them to be able to function as if they were ordinary hosts with
distinct addresses, ordinary network connections, supporting 
ordinary applications - and it just doesn't work well.

Another problem with applying this idea is that it's fine for the 
view external to the NAT, not so good for the view inside the NAT.
NATs try to use ordinary IP as the interface between the NATs and the 
internal hosts, and it's a pretty lousy interface for that purpose.

The one case where this model mostly works is where a NAT is used to
multiplex and load-balance traffic between a set of hosts that
are dedicated to a small number of very specific purposes (usually a 
server farm) - and where the applications running on those hosts are 
specifically chosen, designed, and/or adapted to work in that kind 
of environment.

Received on Thursday, 5 December 2002 19:16:10 EST

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