Layer 3 is not recursive. All the layers are virtual that is what OSI misssed and the entire notion of N+1 view of passing information, in addition to a poor architecture reference model. The virtualization for tunnels are actually done on most implementations in a layer that is developing above transport called the infrastructure layer.
My .25 cents. I see no issue with using tunnels the entire issue of not using them is absurd. /jim > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brian E > Carpenter > Sent: Monday, August 08, 2005 10:44 AM > To: James Kempf > Cc: Internet Area; IAB > Subject: Re: [Int-area] Architectural reasons why tunnelling > is an indicationof a failure > > James Kempf wrote: > > Pekka, > > > > I agree with Joe and Tony. Tunnels are a tool for > virtualizing the address > > space. If you are going to propose that they are a flawed > tool, then I think > > you need to propose an alternative that has "better" (for > some sense of the > > word) properties. The only alternative I can think of (swapping IP > > addresses in the header, i.e. NAT) is worse, but maybe > there are other > > alternatives. > > There is at least one, i.e. the approach taken by shim6, > which explicitly > virtualizes the address ("identifier") seen by upper layers, and > uses a variety of addresses ("locators") at a slightly less virtual > level known as Layer 3, which by the way was invented to virtualize > Layer 2 addresses about 30 years ago. > > If we are thinking forward, I would like to repeat a remark I've made > a number of times, in all seriousness: the flaw in the OSI model is > that it has a finite number of layers instead of being recursive. > It seems that we need to make "Layer 3" recursive to have a clean > virtualization approach. Tunnels slot naturally enough into a > recursive > view of the nextwork layer. > > Brian > > > > _______________________________________________ > Int-area mailing list > [email protected] > https://www1.ietf.org/mailman/listinfo/int-area > _______________________________________________ Int-area mailing list [email protected] https://www1.ietf.org/mailman/listinfo/int-area
