[e2e] Lost Layer?

[Joe Touch]

On 2/11/2014 12:49 PM, Detlef Bosau wrote:
> However, don't you agree that the basic system model in a TCP connection
> is sill
>
> Endpoint 1          -------------------- Pipe
> --------------------------             Endpoint 2

Yes, TCP presents a service of a reliable ordered bytestream between two 
endpoints.

> We can well discuss the nature of the "Pipe", particularly the
> correspondence CWND = Pipe's capacity.

The 'capacity' of the pipe is an ill-defined term; it can mean:

	- amount of sustained throughput through the pipe

	- amount of data stored temporarily inside the
	pipe as a side-effect of efficient communication
		i.e., the average sustained throughput *
		average E2E delay

CWND-MAX is usually set to the latter of these as one optimization, but 
there are others for which that might not be true.

CWND is a part of currently specified TCP congestion control, but not 
the only means nor necessarily the optimium.

Joe