[e2e] where end-to-end ends

[Joe Touch]

Micah Beck wrote:
> 
> The work of Cerf et al on Interplanetary Internet recognizes that the delays
> inherent in transmissions across vast distances makes end-to-end signaling
> impractical.  

Not impractical, necessarily. Just that they highlight the performance
issues that are often overlooked in the E2E principle.

The E2E principle can be considered two component principles:

	E2E principle:
	   E2E services cannot be correctly provided SOLELY by the
	   composition of hop-by-hop (HBH) services.

	HBH corollary:
	   HBH services may be required to improve the performance
	   of E2E services.

The E2E principle is often remembered at the expense of the HBH
corollary. Interplanetary issues just highlight the need for the
HBH corollary. 

> > A new Internet-Draft on the "Interplanetary Internet" was recently
> > published in which the authors (Cerf et al) predict where the end of
> > end-to-end is:
> >
> >   "We have concluded that the standard Internet protocols should be
> >    essentially "terminated" at the Interplanetary Gateways [...]"

That doesn't obviate the need for some E2E sychronization. It just
says that maybe we're willing to use the data _speculatively_ until
we have that confirmation.

Joe