Re: IPv6 news

[David Meyer <dmm () 1-4-5 net>]

On Sun, Oct 16, 2005 at 01:45:40AM -0700, Tony Li wrote:
> > Doesn't NAT, or more specifically the most commonly used, NAPT, create
> > hard state within the network, which then makes it violate the
> > end-to-end argument ? Also, because it has to understand transport and
> > application layer protocols, to be able to translate embedded  
> > addresses,
> > doesn't this also make it violate end-to-end ? I've understood the
> > fundamental benefit of following the end-to-end argument is that  
> > you end
> > up with a application agnostic network, which therefore doesn't create
> > future constraints on which applications can then be used over that
> > network. In an end-to-end "compliant" network, any new transport layer
> > protocols, such as SCTP or DCCP, and new user applications, only  
> > require
> > an upgrade of the end or edge node software, which can be performed in
> > an incremental, per edge node as needed basis. In other words, there
> > isn't any whole of network upgrade cost or functionality deployment
> > delay to support new applications, which was the drawback of  
> > application
> > specific networks, such as the traditional POTS network.
> >
> > Have I somehow misunderstood the intent or benefits of the end-to-end
> > argument ?
>
>
> Mark,
>
> This is probably the most common misunderstanding of the end-to-end  
> principle out there.  Someone else can dig up the quote, but  
> basically, the principle says that the network should not replicate  
> functionality that the hosts already have to perform.  You have to  
> look at X.25's hop-by-hop data windows to truly grok this point.
>
> Many people pick this up and twist it into ~the network has to be  
> application agnostic~ and then use this against NATs or firewalls,  
> which is simply a misuse of the principle.  Really, this is a  
> separate principle in and of its own right.  It's not one that I  
> subscribe to, but that's a different conversation...

        Maybe its time to pull out some of Noel's work on both
        topics. Reasonable introductions to both the e2e
        principle and locator/id split topics can be found on 

          http://users.exis.net/~jnc/tech/end_end.html and
          http://users.exis.net/~jnc/tech/endpoints.txt

        respectively. 

        Dave

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