At 03:42 PM 6/14/01, Dr Rita Puzmanova wrote:
>Thank you all for valid perspectives. Yet my original question (I had on
>mind but perhaps not clearly worded) is still unanswered. I will
>rephrase it:
>
>Does ARP operates at network interface layer or internet layer of TCP/IP
>protocol stack?
Where are you getting those names for TCP/IP layers? I don't see them in
early TCP/IP RFCs.
The original ARP RFC is here, and it doesn't use those terms:
http://andrew2.andrew.cmu.edu/rfc/rfc826.html
The early TCP standard says the four layers are higher-level, TCP, internet
protocol, and communication network. A search of the early IP standard
didn't find the word layer at all!? ;-)
Here's my guess. Check the discussion of layering in Douglas Comer's
Internetworking with TCP/IP, Volume I. He says that "broadly speaking,
TCP/IP software is organized into four conceptual layers: application,
transport, Internet, and Network Interface."
Since 80% of the people on the planet (rough estimate) that learned TCP/IP
learned it from Comer, including authors and tech writers, this conceptual
drawing became "fact" and is explained as THE DOD model, even though DOD
documents don't have such a model. That's my guess.
Priscilla
>Just forget anything else (in particular OSI concepts) - concentrate on
>TCP/IP. To my opinion every protocol must belong somewhere (otherwise
>the whole layering concept would be useless and could not work), it
>cannot be an "interface" (it is a layer protocol, not an interlayer
>protocol within a single system).
>
>No matter whether IETF currently bothers about its own layering system -
>at the beginning they for sure managed to fit the pieces in the puzzle
>(I mean protocols) according to their original, simple
>4-layer-architecture.
>
>Sorry for being soooo persistent ;-)
>
>Rita
>
>Dr Rita Puzmanova wrote:
> >
> > Hi all,
> >
> > Trivial yet fundamental question. I have seen ARP described as part of
> > the network (internet) layer so many times that I have started to
> > believe it belongs there (although I know well that it operates "as if"
> > the Layer 2 protocol - as per OSI RM). Now I have eventually come across
> > Doug Comer's statement: "It's part of the network interface layer."
> >
> > I should not ask where the truth is but still I will. That would mean
> > quite a lot of books are incorrect in this (including Cisco materials).
> >
> > Rita
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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