[e2e] Port numbers in the network layer?

Joe Touch touch at isi.edu
Fri May 10 08:27:46 PDT 2013

On May 8, 2013, at 1:45 PM, John Day <jeanjour at comcast.net> wrote:

> Application names are suppose to be location-independent.  Except on 
> broken OSs, you don't need to know what medium a file is on.

Agreed; this, however, is one of the key failures of the "slice" model of network virtualization. It binds network interfaces and to OS components (slivers), and maps slivers to virtual networks. That inherently inhibits gateways - devices (or slivers) that bridge traffic between different VNs.

> Addresses are suppose to be location-dependent, where given two 
> addresses you should be able to tell if they are "near" each other 
> for some definition of "near."

You're conflating "address" with a knowledge of the topology of its location space.

Location spaces need not be Euclidean or even continuous. Consider street addresses in Tokyo; two addresses on the same street typically satisfy no spatial "nearness" metric (the numbers are sometimes assigned in the order they are built, so 'near' is a temporal metric, rather than spatial).

And not all addresses support aggregation.

Finally, addresses *are* names. A "name" is just an identifier; once you assign meaning, it becomes something else - an endpoint identifier, a location identifier, etc. 


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