Tom.Petch wrote:
If we had a range of transports (perhaps like OSI offered), we could choose the one most suited. We don't, we only have two, so it may become a choice of one
This nicely highlights a dilemma in this topic. The OSI approach to multiple transports ensured that end-to-end interoperability was not achieved!
While the different transports were tailored to different underlying network characteristics, they did not deliver equivalent service to their 'customer' layer, in spite of the fact that those customers needed a uniform service.
I suppose this demonstrates why the discussion should be about layer n and n-1, rather than n and n+1... Focus on the consumer-side of the architecture, when defining the service requirements that need to be abstracted, and then provided by the subordinate layer.
d/ -- Dave Crocker Brandenburg InternetWorking bbiw.net _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf