[e2e] use of MAC addresses

[Christian Huitema]

> Saltzer says that a complete addressing architecture needs
> Application Names, Node Addresses, Point of Attachment Addresses and
> from all of this we get routes.  There is one refinement I would make
> to Saltzer which I think was overlooked because it hadn't occurred
> when he wrote the paper.  Salzter talks about the mappings of
> application names to node addresses, node addresses to point of
> attachment addresses and points of attachments to routes.

Another refinement is the use of multiple hosts for a single
application, e.g. load balancing across a farm of web servers. There is
a need to independently name the application (e.g. the web page at
www.example.com), and the application instance (something like
www.host29.example.com). If you think in terms of DNS mapping to IP
addresses, as we do today, the first name maps to the entire list of IP
addresses of all the servers in the pool; the second name maps only to
the IP addresses of the specific host handling a specific session. One
may also need a name for the session itself, as it could in theory be
"load balanced" between servers. 

-- Christian Huitema