[e2e] e2e principle..where??....

Panos GEVROS P.Gevros at cs.ucl.ac.uk
Mon Jun 4 08:59:50 PDT 2001

John Day typed :

 |the question is where?  The primary argument at the time was: the 
 |PTTs arguing that you didn't need transport protocols that hop-by-hop 
 |was reliable.  While the networking crowd argued that hop-by-hop was 
 |not reliable and never could be and regardless no host was going to 
 |trust the network anyway, so if the hosts were going to do error 
 |recovery, then the network didn't have to do as much and could be 
 |simpler and cheaper.  The PTTs didn't and don't like this because it 
 |makes the network a commodity and a commodity business is hard work. 
 |(Notice how some large router vendors have learned this and talk 
 |about the importance of putting more intelligence in the network. 

"trust" is the key word i'm borrowing from your message -

the conflict between elegant design vs. viable bussiness model above 
has its roots (like many other things) in mutual distrust : the endpoints do 
not trust the network and the network does not trust the endpoints

moreover the assumption that end-points cannot be trusted so that the network 
must be fortified (for resource management etc. which dominated research in 
the 90's) did not have the expected results,

i m not sure whether the end-to-end argument addresses issues of end-point 
"trust" and this is where  everything starts : the providers have to do things 
*inside* their networks

IF the providers could *control* the endpoints  transport functionality 
included (or ensure *conformance*, or *enforce* certain behaviours to the 
endpoints) many problems would magically go away
.. then they couldnt care less about how dumb their network is, and sure they 
wouldn't have any reason why to put more intelligence into it .. they would 
only have to provision (now easier) and their revenue would come from what 
they allow on the end-points

that should be the only way to avoid the conflict above and have the best of 
both worlds : both the network is kept simple and the computation is pushed at 
the end-points.. and the providers do bussiness with it.

otherwise the market forces will enforce PTT-like model (because they 
understand it and they know how to use it do business) and i think it is going 
to happen fast.

so imho there is only one way for the pure internet, e2e, model to survive, 
the end-points (their behaviour,etc) must be trusted ,
i'd put that on top of the research agenda. 

i'd love to hear from people that think the same or are aware of research 
efforts in this direction


 |They don't want to work hard for a buck (or don't know what to do) 
 |and are trying to turn the Net into the phone company model.

 |Since the end2end principle is a statement of what is in the hosts 
 |and what is in the network, everything that is in the application 
 |layer is in a host.  As someone else said, anything that intercepts 
 |and interprets data intended for layers at transport and above 
 |violates e2e.  As I think the same person said, if the intermediate 
 |looks at the higher layer, it must do something about it (whether it 
 |modifies the data or not) otherwise why look at it?  Now this sort of 
 |definition could include the @home type proxies.  Although, I would 
 |argue that since one might get different results depending on whether 
 |the proxy was used, it is a violation.  Others might argue that if 
 |the user didn't know the difference, it isn't!

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