[e2e] a means to an end

Fred Baker fred at cisco.com
Thu Nov 6 14:32:20 PST 2008

On Nov 6, 2008, at 2:16 PM, David P. Reed wrote:

> Fred Baker wrote:
>> It sure is more convenient to be able to include only the people  
>> you want involved in the conversation and leave everyone else out  
>> of it.
> Enabling filtering is the more general idea you are calling for here.

actually, no. I'm not asking everyone else in the room to turn their  
hearing aids off. I'm asking to be able to talk with the intended  
recipient without involving anyone I don't have to.

> We achieve that in wireless networks by "code division  
> multiplexing".  Doesn't need to involve "location" (which would be  
> space-division multiplexing, i.e. beam-forming) to achieve orders of  
> magnitude in efficiency.

OK, let's take your example. To direct a message to your intended  
target, you select the beam that gets to that target. Whatever you  
call that beam, it is your local name for that target at that layer.  
It serves the function of a locator. When you want to direct a message  
to the target, you translate your notion of the target's identity to  
"which communication channel shall I use", which is in the case the  
name of the beam. It tells you the location of your target, in the  
context of a direct wireless network.

"Direct wireless networks" are a special case of "networks". Other  
networks find locators interesting as well, and define them in ways  
appropriate to their technologies just as wireless networks do.

> I'm making an architectural principle argument:  if you want a piece  
> of information, there are many ways to reduce the waste/cost/...   
> and switching the communications based on "place" is *not the  
> fundamental one*.  That said, sometimes it is.  If most of your  
> communications is via fiber, mostly between elements that don't  
> move, and where those containers contain a largely static collection  
> of information, then "location" turns out to be useful.   Whole  
> industries can be built on it that last maybe 25 years or more, and  
> that's not bad.

yes. that said, there are fairly long-lived industries that base what  
they do on "current location" as well. consider mobile telephony,  
whatever name and technology you want to apply to it. A telephone  
number is essentially an identifier for the computer that can tell  
where your intended audience is coupled with the information it will  
need to identify them. That computer translates that into an IMSI,  
which is a binary identifier for the handset-or-whatever. As the  
handset moves in the network, it registers with cell after cell, which  
in turn register their association with the IMSI with the computer in  
question. A circuit gets set up, and as you move the circuit trails  
along behind you as you pass through various cells.

The telephone number is a name, and the IMSI is a name. But the  
information gets translated (by registration) to a location (a cell)  
and perhaps the location of a communication (a circuit).

Place may not be fundamental. But it sure is useful.

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