[e2e] Port numbers in the network layer?

John Day jeanjour at comcast.net
Wed May 8 13:45:33 PDT 2013

Wasn't this obvious?    This is why they were called network 
"addresses" and not names.

The parallel was to OSs.  As Shoch put it, Application names indicate 
"what" and addresses indicate "where" and routes were "how to get 
there."  He didn't quite have the whole picture but close enough for 
this discussion.

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

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."  (not necessarily implying physical 
location, that while it can be useful is just the naive first 
thought.)  Although street addresses often have this property to 
varying degrees.  ;-)  Chicago more so than Boston!  ;-)

Although as I finally realized, application names are 
location-dependent too, just with a different meaning of "location."

At 2:52 PM -0400 5/8/13, Noel Chiappa wrote:
>     > At 7:53 AM -0400 5/3/13, dpreed at reed.com wrote:
>     > (especially due to the much later decision to conflate
>     > endpoint-identifier with route that got made by default at BBN, perhaps
>     > just to get the thing bootstrapped)
>I see that differently...
>The thing is that path selection, to scale, just has to have a namespace in
>which things can be aggregated. (You just can't give everyone a complete map
>of every last physical asset in the entire network.) IP _only had one
>namespace available_. So, yeah, as the network grew it had to be organized in
>a way that was aggregatable.
>That started to happen early on, with subnets, although it didn't come into
>full flower until later, with CIDR. Yes, the very early network did have
>addresses that (at the 'network' level) were flat - but even then, hosts were
>not free to move from network to network and keep their 'identity' - because
>internet-wide path selection didn't (couldn't?) track individual hosts.
>It was inevitable that that aggregation would ensue as the network got larger
>- as a direct, and unavoidable consequence of the fact that IPv4 had only one
>A number of related issues were pointed out by Jerry in the paper that
>eventually became RFC-1498, and those too pointed the same way: not enough
>	Noel

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