RE: Identification, layering, transactions and universal connectivity

["Tony Li" <Tony.Li@procket.com>]

|    - Work on the address selection problem.


I don't want to discourage all of the metaphysics, but I would
like to mumble a bit about this part of the problem.  What are
the boundaries of the solution space for this particular area?
Ultimately, in a utopian world, we'd like an oracle that gives
us the perfect pair of addresses to use for any given communication.
These addresses would not only provide reachability, but would
provide optimality in routing, latency etc.

Back in realityland, we have no such oracle.  If we want to 
make an intelligent decision, we need to have data to base that
decision upon.  Without the data, possibly via indirect access,
we are guessing, tho that's not necessarily a bad thing.  See
Ethernet.  

The data that we would like to have includes topological connectivity,
including policy constraints, available bandwidth, latency, QoS
availability, etc. ad nauseum.   Where is that data today?
Some of it is in the routing subsystem.  Most of it is not
collected today.  Much of it is real-time information, so 
not maintaining a 'current' copy would make the information
worthless.  And the overhead of storing the information and
distributing it is pretty clearly daunting.  

Instead of trying to swallow this huge mountain of data, we
have a very simple alternative: perform experiments.  By
simply trying the addresses that we get from our addressing
system and actually sending the packets, we are, in effect,
gathering the data that we want to make a decision in the
first place.  

This also has the advantage that we can vary the amount of
effort that a particular application/host puts into selection.
Some hosts that only require reachability can do simple 
linear search.  Other hosts can do parallel searches of the
possible connections, plus do periodic evaluations to see if
there are more optimal alternatives over time.  

The network control plane does not change from the functions
that we have available today.  In other words, the problem
is already solved.

Tony