Hierarchy, Force Monopoly, and Geodesic Societies

[Eugen Leitl]

On Fri, Apr 09, 2004 at 08:29:27PM +0100, Jim Dixon wrote:

> Yes.  I know what a tree is, and I am quite familiar with structure of
> the Internet.  These very pretty pictures certainly look like the Internet
> I am familiar with, but don't resemble trees.

There's a continuum between a tree and a high-dimensional grid/mesh/lattice.
A high dimensional grid pressed upon a flat surface looks like a bush at each
node, with decaying connectivity density with the density. I don't have a
sketch at hand, unfortunately, so I can't put both extreme cases next to each
other.

The Internet is a tree, not a mesh.

> Over the last 30 years or so, various people have hypothesized about what
> the "killer requirement" might be.  To the best of my knowledge, all have
> been wrong.

Computational physics in a relativistic universe imposes very clear
constraints. There's nothing whatsoever hypothetical about these constraints.
There's nothing whatsoever hypothetical that if you want to do relativistic
cut-through switching of serial signals (10 GBit Cu, TBit fiber, LoS laser)
you
have to make a routing decision very, very early. Before the packet header
has left the delay line (and the rest of the packet is streaming at you
through the medium, whether vacuum or glass, or solid-state optical delay
line). Medium is a natural FIFO, which of course only becomes apparent beyond
GBit/s data rates. A photonically switched crossbar making use of it gets rid
of expensive (time, energy) photon-electron-photon conversion, and scarce
resource memory real estate, and memory bandwidth. It doesn't matter that in
the current postdotbomb dark fiber is plentiful, and photonics is notoriously
cash-drained. Traffic is growing, and will absorb those overcapacities
eventually. Intermachine traffic, people will have become irrelevant pretty
soon, if they haven't already (but for multimedia streams, which will
saturate as well, because population grows way too slow to become visible,
only technology deployment rate is visible).

This is the reason why the future asks for specific frame/packet header
layout, specific
wiring of connections, and purely local-knowledge routing (extreme
localization or elimination of admin traffic), with a routing
decision done in ~ns domain (and below).

> The Internet is quite obviously optimizing along certain lines.  However,
> these lines don't follow any geographical geodesic, which was my point.

I'm not going to argue with you. Look up physical plots of connectivity over
Earth surface. Start with GEO/LEO satellite, sea cable, then progress to large
scale
cable layouts, then to grassroot scale (city and neighbourhood and house
level).

> If you try to replace observations with theories, the most important thing
> is to verify that your theory corresponds with reality right now.  If your
> theories aren't correct "currently", it is very unlikely that they will be
> a better fit tomorrow.

Non sequitur.

> It isn't a minor point that the Internet is fractal.  This is in fact
> what is consistent everywhere and has been, to the best of my knowledge,
> throughout the history of the Internet.  If you go back to your pretty
> pictures and look, you will see fractal structures.

Dude, hypergrids *are* fractal. Not that it has to do anything with the
current topology.

> A geodesic is a minimal path in whatever geometry you are talking about.

The geometry on Earth surface is anything but whatever. Way above, with nodes
in mutual plain view, it's plain old Einstein-Minkowski (basically Euclidian,
with relativistic corrections).

> If you looked carefully at traffic between European countries around
> 1999, it turned out that the minimal cost path between say German and
> France was in fact through Virginia.  Traffic was following a geodesic --
> but not a geographic geodesic.

Again, how about traffic in US? EU is weird, Asia is yet too new (but
adapting very rapidly).

Again, how about traffic in your above constellation in 2004?

Again, how about physical cable connecting the nodes?

I'm claiming peering arrangement evolve to make optimal use of given physical
cabling. This is quick.

On the longer term, physical and virtual (radio, laser) cabling evolves to
minimize the load on existing links. This is slower, peering arrangements
change in realtime in comparison, very like Franck-Condon principle.

> As I recall, a 2 Mbps E1 between most major European cities and Virginia
> was about $30,000 a month, but an E1 across the English Channel was around
> $45,000 a month - 50% more to go 30 miles than to go 6,000.  We had
> customers in Northern Ireland whose traffic to Dublin went first to
> London, then to our PoP in California, then to Virginia, and from there
> back to Ireland.  This was our financial geodesic.

Why do people lay fiber in a specific place?
How do peering arrangements evolve over time?
How is the rate of optimization going to change if agoric load levelling is
implemented at protocol level?

> Indeed.  But the point is that things tend _not_ to be optimized at the
> macro level; what happens is the opposite, micro-optimization around the
> results of previous decisions (some of which will have been just plain
> wrong).  Roman engineers built roads a couple of thousand years ago,
> optimizing things according to then-current theories and strategies.  We
> lay down rivers of fiber along those roads, reenforcing those ancient
> decisions, because the cost of reversing those ancient decisions, and all
> of the incalculable number of micro-decisions that followed, would be
> truly enormous.
>
> You can see the same pattern working itself out now.  A group of Japanese
> banks invested in a building in Docklands, Telehouse, to act as a backup
> facility in case of a disaster in the City of London.  This turned out to
> be a loser, in financial terms.  The Japanese had misjudged the market
> demand for this kind of facility.
>
> Some telcos had put a few racks in the building.  The first UK ISPs
> followed them there, because the facility was cheap.  More ISPs followed.
> Some decided to build an exchange point there, the LINX, following
> somewhat misunderstood US models.  Things mushroomed; the building, which
> had been quiet and empty, rapidly filled up with racks.  The owners built
> another building across the street; investors built competing facilities a
> short distance away, to be close to the action. All of these were
> interconnected with more and more fiber.

Very interesting. Thanks for this story from the trenches.

> The end result is that most UK Internet traffic, and a large part of
> European traffic, passes through what used to be a more or less derelict
> area of East London, all because of a planning error on the part of some
> Tokyo-based banks.

A nexus is a classical tree artifact. Once the network progresses along a
meshed grid hugging Earth surface, we're going to see an increase in
crosslinks and exchange points, crosslinking the branches.

> Not at all.  Everywhere we see the same pattern of pearl-like growth:
> someone makes a decision, and those that follow build around the first
> decision, micro-optimizing as they go along, creating the odd fractal
> shapes that are all around us.

I'm stuck with a notbook display and keyboard right now, but it would be fun
to pull up graphs linking topology to geography, and change in such graphs
over time. Informally, I hear topology converging to geography, but it would
be nice to see actual animations showing it happen.

> > future, everywhere, looks even more different.
> > We're at the beginning of the optimization process. You can't cheat
physics
> > in a relativistic universe, in an economic/evolutionary context.
>
> This isn't physics.  It's much more like biology.

Biology is subject to physics. At all scales. When it comes to communication,
constraints on energy and signalling and shape become especially obvious.

Computational physics is just such a source of constraints. Except, here
energy is not (yet) a constraint (dissipation rate is already), relativistic
singnalling is (in comparison to biology, which is energy constrained, aand
is waaay to slow to be relativistically constrained, only saltatoric spike
propagation, which is arond 100 m/s, so it has to deal with latency as well
when laying out the computational circuits).

--
Eugen* Leitl <a href="http://leitl.org">leitl</a>
______________________________________________________________
ICBM: 48.07078, 11.61144            http://www.leitl.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
http://moleculardevices.org         http://nanomachines.net

[demime 1.01d removed an attachment of type application/pgp-signature]