Re: [tae] [tsv-area] Transport negotiation

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Stuart (et al.),

Stuart Cheshire wrote:
> On 3 Dec, 2008, at 13:57, james woodyatt wrote:
>> The "transport layer" is identified by the upper layer protocol header
>> at the end of the extension header chain of the inner-most
>> encapsulated IP packet.
> 
> 
> This might be a fine answer to the question, "What is the transport
> layer?" on the mid-term exam for an introductory undergraduate
> networking class.
> 
> The notion of layers in networking is an artificial simplifying
> assumption introduced to help us think about software design (and to
> help ISO divide their people up into seven committees).

That's one perspective; I have another, e.g.:
http://www.isi.edu/rna/

This is somewhat similar to John Day's view on layering.

...
> Bryan Ford's excellent "Breaking Up the Transport Logjam" presentation
> pointed out that what we call the "transport layer" artificially takes
> three functions (demux, flow control, and operational abstraction) and
> lumps them together in what we traditionally call "transport layer",
> while leaving out other functions (session, presentation, etc.) and
> artificially deeming them to be "not transport layer". 

His approach doesn't consider that these features exist at other layers.
All layers are capable of:
	state coordination (soft, hard, etc.)
	flow control
	error recovery
	order restoration
	multiplexing/demultiplexing
	framing
	security
	etc.

What distinguishes layers, IMO, is scope and the relation to the
services it requires a-priori. I don't consider the above the unique
purvue of the transport layer, to be sure.

Joe

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iEYEARECAAYFAkk/DoEACgkQE5f5cImnZrvSqQCgiDA0a6+ggbt/3e2HhZPId4oW
r7kAoLaeHwY9OyQr0CVB4L1WDm7iVhjF
=5fs4
-----END PGP SIGNATURE-----
_______________________________________________
tae mailing list
tae@ietf.org
https://www.ietf.org/mailman/listinfo/tae