It would make more sense for an application to make a call to an API that
says "I want to hand off identifying information about host X to host Y.
Please package me up information to sent to X so that it will be able to
understand what I mean."
been there, tried to do that, in the context of PVM. by far the easiest way
to accomplish this is to have a uniform address space at the network level.
any other approach is just too complex.
background: PVM was originally designed to as a uniform API for distributed
memory parallel machines, and later as a way to provide a distributed memory
programming environment across a network of computers (some of which were
potentially distributed memory hosts). in order to allow applications to send
messages to other "processing elements" or hosts, PVM assigned a task id to
each "processing element" in its virtual machine, and the mapping between task
ids to tasks was uniform across the virtual machine. this task id consisted
of a host id to which a host-specific offset was added. we tried making the
mapping non-uniform because it would have relieved us of the need to keep a
mapping table consistent across all hosts in the machine (especially after we
allowed new hosts to be added to the machine), but the most robust, and in
general the most efficient, way to implement the host-id mapping function was
to use consistent numbering for host-ids across the entire machine...that, and
expecting apps to invoke a translation function every time they
passed a task id to another task was just too cumbersome.
uniform addressing models are very compelling, even when you don't have
complete interconnection.
A mention of proper layering was made earlier in this discussion thread.
It's time we took a serious look at how to improve on the mechanisms used.
Solving this layering issue could benefit both IPv4 and IPv6
implementations. As noted, the problem is not new at all, though perhaps
now is the time to shed light on the matter.
proper layering is an art. it involves understanding when to enforce layering
discipline, and when to escape it.