[e2e] administrative domains and the network layer

Ben Black ben at layer8.net
Mon Jun 4 23:44:43 PDT 2001

Much of the recent discussion on this list regarding what the end to end
principle means in the context of the current Internet has overlapped in
my mind with some private discussions on how to effectively multihome in
IPv6 (and IPv4, to some extent).  Many paths seem to naturally lead back
to a solution using NAT or one of its relatives, such as GSE, and I have
seen others argue that such solutions violate the end to end principle.

Whether or not NAT actually violates the end to end principle is a 
question I do not currently care to ask, but I have begun to wonder if
part of the conflict might reside in the current OSI layering model,
specifically in its definition of the network layer.  A key mechanism
in managing a network as large as the Internet is the autonomous system.
Autonomous systems are used within the routing system, but are completely
ignored within the network layer.

If the autonomous system concept were to be introduced into the 
definition of the network layer, I see the opportunity to truly decouple
host identity from network topology (this is not the same as trusting the
host, as I believe issues of trust are well beyond the scope of the 
network layer), which in turn opens the door to far simplified and
scalable routing architectures (whether they use something akin to GSE,
NAT, or a completely new approach).

I am interested in whatever opinions you might have on the subject.


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