[e2e] a means to an end
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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