I was merely pointing out that your catechismic canard about "no fully worked
out example of separating location and identity" is ludicrous on its face,
usually when people talk of the problem as one of separating location and
identity, they haven't clearly defined the problem, or they're only
looking at one part of the problem (whereas someone else using the
same problem description may be looking at a different part of the problem)
The IP address is commonly used as, or as part of, at least the following:
- host identity
- host-to-network interface identity
- location of the host's network interface relative to the network topology
- application rendezvous point (socket or process identity)
- service identity (where the service can consist of multiple hosts)
- TCP connection state identity
- remote host identity (for rtt estimation)
this is just off the top of my head, and it doesn't even consider mobile IP
or most kinds of NATs.
the problems caused by the overloading are mostly that it is very
difficult for any of these identities to change relative to the others -
the mapping function between them is assumed to be the identity, and
this assumption is wired into countless pieces of code.
but if you build a "solution" that lets you separate one of these functions
from another, it gives you only one additional degree of freedom - it
doesn't "solve" the problems resulting from the other kinds of overloading.
for instance you can separate "host identity" from location for the purpose
of authentication, but it still doesn't let you change the host's address
without breaking the utility of that address as a rendezvous point in a
distributed system.
and yet you clearly don't want separate values for each of these -
this would add a tremendous amount of complexity and overhead.
nor does it appear to be a good idea to assume that these values will
always be separate - for instance, there's an argument that stationary
hosts are common enough that you want to optimize for that case -
you want to support mobile hosts but you don't want to pay for the
extra layer of indirection/lookup when sending packets to stationary hosts.
Keith