Hi Bill,

> A MAC address doesn't "point" or DO anything else. It's just a big integer.

Exactly my point.  The properties of the namespace include global
uniqueness, but not location (topological, geographic, or otherwise).
 
> A MAC address is USED by at least three distinct functions:
> 
> 1. By a switch determining which port or ports to repeat a received packet on.
> 2. By a NIC determining whether a particular packet should be repeated
> from the wire to a host's software stack.
> 3. By a network stack preparing to transmit a particular packet to its next
> hop.
> 
> 
> What identification function do you see happening here? All I see is
> forwarding decisions.


Again, function 1 does not make the namespace topologically sensitive.  It's
just using a flat identifier space and explicitly learning the location of
the identifier.  This is clear if you consider the situation before the host
generates a packet: before the switch learns of the identifier, it has NO
idea where the host is in the network.  And again, you can do this on ANY
flat namespace.  Doesn't make that namespace an address.

Function 2 is filtering based on an identifier.

Function 3 is simply including a source identifier.  It's only real purpose
is to support the learning function for function 1.

Tony


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