[e2e] Port numbers in the network layer?

John Day jeanjour at comcast.net
Fri May 10 15:22:05 PDT 2013

At 8:27 AM -0700 5/10/13, Joe Touch wrote:
>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.

Boy, you are right about that!  It is *one* of the failures.  ;-)

>>  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.

No, I am conflating address with the homeomorphism used to create the 
address space.

>Location spaces need not be Euclidean or even continuous.

No one suggested they did.   The peculiar thing about examples is 
that they are *examples* and represent only a single point in what 
could be a very large space.  They don't necessarily have all the 
properties of all the other examples from the same space.  Very 

>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.

Actually, this is incorrect.  All addresses support aggregation 
(given the previous definitions I used).  Although not all 
aggregations are useful for finding routes or establishing "physical 

>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.

Absolutely.  An address is a type of name.  Nothing new there.  That 
has been well accepted as long as I have been around.



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