At 01:56 PM 4/8/04 -0400, R. A. Hettinga wrote:
[Nanotechology at least holds out the possibility of making Von Neumann machines, that is, switches which make copies of themselves,
You mean Johnny's *replicators*, a vN machine is just one with a changable program store. But you mentioned Jared Diamond (and used the phrase "proto-cat") so you are forgiven. When a bunch of
these networks are hooked together, you get a ubiquitous geodesic internetwork, the internet,
Geodesic means shortest path, and you'll note if you play with tracert that the shortest path (as seen on Earth's surface) is rarely taken. What you really mean is "highly & cheaply connected", although your investment in the word "geodesic" is probably too far gone for you to change.
At 11:28 AM -0700 4/8/04, Major Variola (ret) wrote:
Geodesic means shortest path, and you'll note if you play with tracert that the shortest path (as seen on Earth's surface) is rarely taken.
Measure the path in time? :-) Cheers, RAH -- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'
On Thu, Apr 08, 2004 at 03:29:58PM -0400, R. A. Hettinga wrote:
At 11:28 AM -0700 4/8/04, Major Variola (ret) wrote:
Geodesic means shortest path, and you'll note if you play with tracert that the shortest path (as seen on Earth's surface) is rarely taken.
A pretty densely distributed radio mesh with good (geographic routing) algorithms would tend to use the shortest path. Very small cells based on current WiFi or ultrawideband/digital pulse radio might have to route around obstacles (large high buildings, flow along the nodes with aerials dangling into the streets). MobileMesh doesn't seen to be the single solution, at least one contender exists. Both are being used in practice, alas not yet in your $100 garden-variety WiFi routers (these do bridging already, though). Internet is mostly a tree (if you look at the connectivity maps). Wires over long distances will tend to follow geodesics (because cables are expensive, and an enterprise will try to minimize the costs). Current flow is mostly dictated by frozen chance, politics (peering arrangements). Automating peering arrangments and using agoric load levelling in the infrastructure will tend to erode that over time. Over time, physical lines will tend to be densest along densest traffic flow. American cities are orthogonal, European usually radial. The cities are connected with traffic ducts (rail, highway) which is typically loosely geodesic (but for obstacles in the landscape). Fiber typically follows railway or highway. Easiest is a cloud of satellites with mutual time of flight triangulation, and line of sight laser signalling.
Measure the path in time?
UWB gives you realtime location in each node down to cm scale. No idea how difficult to ToF triangulate with multipath. The higher device density, the less confusion. Intel's pushing UWB as wireless USB substitute. No reason why it couldn't cover 10 miles of open terrain with enough power and proper aerials. Anyone knows how UWB handles directional aeriales? Does it prefer fractal emitters, or are there specific optimal radiator geometries? -- 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]
On Fri, 9 Apr 2004, Eugen Leitl wrote:
Internet is mostly a tree (if you look at the connectivity maps).
Not at all. A tree has a root; the Internet doesn't have one. Instead you have several thousand autonomous systems interconnecting at a large number of peering points.
Wires over long distances will tend to follow geodesics (because cables are expensive, and an enterprise will try to minimize the costs).
For a long time, most traffic between European countries was routed through Virginia. This has improved only in the last few years. In the same way a lot of Pacific traffic still runs through California. In each case what matters is not geography but politics and quixotic regulations. Within most countries the same sort of illogic applies. In the UK, for example, most IP traffic flows through London, and within London most IP traffic flows through the Docklands area, a geographically small region of East London. It's fractal: even within Docklands, almost all traffic flows through a handful of buildings, and there is a strong tendency for most of that inter-building traffic to pass through a very small number of ducts.
Current flow is mostly dictated by frozen chance, politics (peering arrangements). Automating peering arrangments and using agoric load levelling in the infrastructure will tend to erode that over time. Over time, physical lines will tend to be densest along densest traffic flow.
Very true -- but this has nothing to do with geodesics.
American cities are orthogonal, European usually radial. The cities are
? City layouts that I am familiar with are either haphazard or built around rings or some mixture of the two. MFS built a US national ring, a ring in New York City, a ring in London, and rings elsewhere in Europe. Other carriers tended to follow the same pattern.
connected with traffic ducts (rail, highway) which is typically loosely geodesic (but for obstacles in the landscape). Fiber typically follows railway or highway.
That's certainly true, but now you are talking about political decisions made ages ago. Many roads in England were built by the Romans. These roads lead to London. You see the same pattern on the Continent, of course, with the roads leading to the local capital (Paris, say) and then on to Rome. That is, fiber optic paths today reflect the strategic requirements of the Roman Empire, not geometry. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
On Fri, Apr 09, 2004 at 06:22:06PM +0100, Jim Dixon wrote:
On Fri, 9 Apr 2004, Eugen Leitl wrote:
Internet is mostly a tree (if you look at the connectivity maps).
Not at all. A tree has a root; the Internet doesn't have one. Instead you have several thousand autonomous systems interconnecting at a large number of peering points.
A modestly high dimensional grid of some billion nodes doesn't look like this: http://members.easynews.com/L4/opte/www.opte.org/maps/static/1069646562.LGL.... D.700x700.png This is clearer: http://research.lumeta.com/ches/map/gallery/wired.gif It should look a lot like a Golgi stain of your neocortex, though, the horizontal component being dominating (until we've get several million birds zooming over our heads in the starry sky). The neocortex and the human CNS in general is also laid out in a specific way, because it's also been/is subject to massive optimisation, both evolutionary and in course of operation.
For a long time, most traffic between European countries was routed through Virginia. This has improved only in the last few years. In the same way a lot of Pacific traffic still runs through California. In each case what matters is not geography but politics and quixotic regulations.
You're proving my point. The network started as a bureacratic, static, tiny, suboptimal configuration. As it grew bigger, and started participating in economy it started minimizing itself. This isn't just connectivity, but goes down to the protocol level. We know IPv6 isn't the answer, mostly because it is largely geography agnostic, can't handle nodes moving with orbital speeds (or even a speeding car), doesn't handle interplanetary latencies and isn't local-knowledge routed/switched in general. It also can't handle relativistic speed cut-through, which is the killer requirement.
Within most countries the same sort of illogic applies. In the UK, for example, most IP traffic flows through London, and within London most IP traffic flows through the Docklands area, a geographically small region of East London. It's fractal: even within Docklands, almost all traffic flows through a handful of buildings, and there is a strong tendency for most of that inter-building traffic to pass through a very small number of ducts.
You're correct, currently. Things will become better as network ages, and especially if we get cellular radio architectures in densely populated areas (there's about a GBit/s worth of wireless bandwidth within a small cell, when we ignore THz and optical wavelengths).
Current flow is mostly dictated by frozen chance, politics (peering arrangements). Automating peering arrangments and using agoric load levelling in the infrastructure will tend to erode that over time. Over time, physical lines will tend to
be
densest along densest traffic flow.
Very true -- but this has nothing to do with geodesics.
Human societies optimize. Geodesic is a shortest path on Earth surface. Look at Christaller and followup (Christaller and geodesics is good first start).
? City layouts that I am familiar with are either haphazard or built around rings or some mixture of the two. MFS built a US national ring, a ring in New York City, a ring in London, and rings elsewhere in Europe. Other carriers tended to follow the same pattern.
I'm not going to dive into city architecture, but compare these two adjacent cities: http://www.redtailcanyon.com/items/18393.aspx
connected with traffic ducts (rail, highway) which is typically loosely geodesic (but for obstacles in the landscape). Fiber typically follows railway or highway.
That's certainly true, but now you are talking about political decisions made ages ago. Many roads in England were built by the Romans. These
A road is a place channeling traffic from A to B. Roman roads which are still used (I use one quite frequently) were created between areas of major human activity, requiring traffic frequent enough to warrant an expediture (in terms of wealth fraction, roman roads were just as expensive as autobahns).
roads lead to London. You see the same pattern on the Continent, of course, with the roads leading to the local capital (Paris, say) and then on to Rome. That is, fiber optic paths today reflect the strategic requirements of the Roman Empire, not geometry.
1) today, EU today, elsewhere, looks different. 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. -- 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]
On Fri, 9 Apr 2004, Eugen Leitl wrote:
Internet is mostly a tree (if you look at the connectivity maps).
Not at all. A tree has a root; the Internet doesn't have one. Instead you have several thousand autonomous systems interconnecting at a large number of peering points.
A modestly high dimensional grid of some billion nodes doesn't look like this: http://members.easynews.com/L4/opte/www.opte.org/maps/static/1069646562.LGL.... This is clearer: http://research.lumeta.com/ches/map/gallery/wired.gif
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.
For a long time, most traffic between European countries was routed through Virginia. This has improved only in the last few years. In the same way a lot of Pacific traffic still runs through California. In each case what matters is not geography but politics and quixotic regulations.
You're proving my point. The network started as a bureacratic, static, tiny, suboptimal configuration. As it grew bigger, and started participating in economy it started minimizing itself. This isn't just connectivity, but goes down to the protocol level. We know IPv6 isn't the answer, mostly because it is largely geography agnostic, can't handle nodes moving with orbital speeds (or even a speeding car), doesn't handle interplanetary latencies and isn't local-knowledge routed/switched in general. It also can't handle relativistic speed cut-through, which is the killer requirement.
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. The Internet is quite obviously optimizing along certain lines. However, these lines don't follow any geographical geodesic, which was my point. And it is only obvious what the lines of optimization are in hindsight ;-)
Within most countries the same sort of illogic applies. In the UK, for example, most IP traffic flows through London, and within London most IP traffic flows through the Docklands area, a geographically small region of East London. It's fractal: even within Docklands, almost all traffic flows through a handful of buildings, and there is a strong tendency for most of that inter-building traffic to pass through a very small number of ducts.
You're correct, currently.
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. 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.
Things will become better as network ages, and especially if we get cellular radio architectures in densely populated areas (there's about a GBit/s worth of wireless bandwidth within a small cell, when we ignore THz and optical wavelengths).
dictated by frozen chance, politics (peering arrangements). Automating peering arrangments and using agoric load levelling in the infrastructure will tend to erode that over time. Over time, physical lines will tend to be densest along densest traffic flow.
Very true -- but this has nothing to do with geodesics.
Human societies optimize. Geodesic is a shortest path on Earth surface. Look at Christaller and followup (Christaller and geodesics is good first start).
A geodesic is a minimal path in whatever geometry you are talking about. 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. 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.
? City layouts that I am familiar with are either haphazard or built around rings or some mixture of the two. MFS built a US national ring, a ring in New York City, a ring in London, and rings elsewhere in Europe. Other carriers tended to follow the same pattern.
I'm not going to dive into city architecture, but compare these two adjacent cities: http://www.redtailcanyon.com/items/18393.aspx
I have spent time in both cities and am familiar with their layouts, but really can't see how this relates to how fiber is laid out in Europe and America.
connected with traffic ducts (rail, highway) which is typically loosely geodesic (but for obstacles in the landscape). Fiber typically follows railway or highway.
That's certainly true, but now you are talking about political decisions made ages ago. Many roads in England were built by the Romans. These
A road is a place channeling traffic from A to B. Roman roads which are still used (I use one quite frequently) were created between areas of major human activity, requiring traffic frequent enough to warrant an expediture (in terms of wealth fraction, roman roads were just as expensive as autobahns).
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. 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.
roads lead to London. You see the same pattern on the Continent, of course, with the roads leading to the local capital (Paris, say) and then on to Rome. That is, fiber optic paths today reflect the strategic requirements of the Roman Empire, not geometry.
1) today, EU
today, elsewhere, looks different.
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.
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. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
At 8:29 PM +0100 4/9/04, Jim Dixon wrote:
Traffic was following a geodesic -- but not a geographic geodesic.
Right. Geodesic is a topologic content. In three (two?) dimensions, a geodesic is a great circle route across a sphere. In higher dimensions, it's something else. No. I don't know the math. :-) Cheers, RAH -- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'
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.
future, everywhere, looks even more different. We're at the beginning of the optimization process. You can't cheat
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. 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]
On Sat, 10 Apr 2004, Eugen Leitl 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 "tree" as the term is used in mathematics and computer science has a single root. A continuum has an infinite number of points in it. A grid ... none of these terms has anything much to do with one another.
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.
I don't know why you introduce hypergrids. But you might consult a mathematical dictionary - the term seems irrelevant to the current discussion.
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).
"The geometry on Earth surface is anything but whatever"? Sorry, this makes no sense. However, a geodesic remains a path of minimal length in the geometry under consideration. Or so it was when I last did some reading in finite dimensional metric spaces.
I'm claiming peering arrangement evolve to make optimal use of given physical cabling. This is quick.
As the term is normally used, "peering" is the settlement-free exchange of trafic between autonomous systems (ASNs). "Settlement-free" means that no consideration ($$$) is paid. This has bugger all to do with cabling.
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.
Peering arrangements generally involve legal departments, and rarely change once inked. In the real world, peering policies normally reflect a mixture of common sense and total misunderstanding of what the Internet is about. Some networks just peer with anyone; some have incredibly detailed contracts and involve months of negotiation. When senior management is involved, they quite often have a telco background, and think that peering has something to do with SS7. That is, they try to insist that the Internet is really just the same as the voice telephone network, and BGP4 is SS7. The results are often comic.
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.
What do you think "nexus" means?? Conventional definition: ---------------------------------------------------------------------- n. pl. nexus or nexuses 1. A means of connection; a link or tie: this nexus between New York's... real-estate investors and its... politicians (Wall Street Journal). 2. A connected series or group. 3. The core or center: The real nexus of the money culture [was] Wall Street (Bill Barol). ---------------------------------------------------------------------- As Lewis Carroll tried to make clear a long long time ago, it isn't very useful to conduct arguments by redefining words as you go along. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
On Sun, Apr 11, 2004 at 12:29:11AM +0100, Jim Dixon wrote:
A "tree" as the term is used in mathematics and computer science has a
A tree as the term is used in a human language refers to a shape. Ditto mesh. Have you seen a fisherman's net? Do you think a fisherman or a weaver uses a mathematical formalism when referring to a specific, familiar shape? The graph (not a mathematical term, that) I pointed you to did remind you of...? http://research.lumeta.com/ches/map/gallery/wired.gif
single root. A continuum has an infinite number of points in it. A grid
Use your imagination. Crosslinking a tree results in a mesh. Are you familiar with polymer crosslinking? Can you imagine a crosslinked tree, that is halfway between a tree, and a mesh? I knew you could.
... none of these terms has anything much to do with one another.
I'm sorry I'm confusing you with interdisciplinary language. Unfortunately, I'm not going to lapse into formal definitions of new terms, if these can be informally explained in downstream text.
I don't know why you introduce hypergrids. But you might consult a
You're using "don't know" a lot. I recognize the symptoms by now. Occasionally, I run into people who're into heavy formalism & domination. I've almost never been able to communicate effectively with such people, but I'm going to try anyway. I use the term hypergrid/hyperlattice/hypermesh as a generic term for higher dimensional networks which have a specific connection locality pattern, if mapped to 2d and 3d space. Namely, that the connection density decays with distance (in terms of distance to the current reference node). The higher the dimensionality, the larger the total number of links. The more random defects (missing edges) in the network, the less orthogonal it looks. A hypercube is an instance of a pretty orthogonal high-dimensional network. Its makeup is fractal, which is visible in the connectivity matrix. A hypergrid is an orthogonalized hypercube. You can plot (project) hypercube and hypergrid connectivities on 2d and 3d arrays of nodes. If the length of the array edges is a power of 2 you'll get a specific connectivity distribution pattern, reaching outwards orthogonally in distances which are doubling in each step. I generalize this by relaxing the 2^n distance constrant and by allowing connectivity other than orthogonal, including defectivity. The connection density still decays exponentially with distance. Less fuzzy now?
mathematical dictionary - the term seems irrelevant to the current discussion.
Trust me, it's not.
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).
"The geometry on Earth surface is anything but whatever"? Sorry,
Now you're refusing to parse English, too. I'm not going to diagram it for you, look at above cited passage.
this makes no sense. However, a geodesic remains a path of minimal length in the geometry under consideration. Or so it was when I last did some reading in finite dimensional metric spaces.
I'm claiming peering arrangement evolve to make optimal use of given
Look outside the window. Does this look like a finite dimensional metric space to you? Are you familiar with geodesy? Are you familiar with the term geodesic as used by ship captains and pilots? It has nothing whatsoever to do with spacetime curvature. You can't travel nor signal through Earth bulk, so you have to route your signals around the spherical obstacle. One you're sufficiently far removed, it's line of sight in a device cloud (a satellite constellation). physical
cabling. This is quick.
As the term is normally used, "peering" is the settlement-free exchange of trafic between autonomous systems (ASNs). "Settlement-free" means that no consideration ($$$) is paid. This has bugger all to do with cabling.
Peered traffic is exchanged over a point. It is frequently called a nexus. The traffic needs a physical connection to pass through the nexus. Traffic requires infrastructure, which costs money to buy and to run. Unnecessary traffic and suboptimal topology incurs unnecessary costs. Current layout is done by people, and is a political process. Traffic laid out by agorics within a protocol adjusts in realtime. Because this is not being done now, this means such protocols will be invented and deployed. They will outcompete the legacy approach. It doesn't take a genius to make that trivial forecast.
Peering arrangements generally involve legal departments, and rarely change once inked.
The worse for them. Computers can negotiate, too, and a lot quicker than people.
In the real world, peering policies normally reflect a mixture of common sense and total misunderstanding of what the Internet is about. Some networks just peer with anyone; some have incredibly detailed contracts and involve months of negotiation.
When senior management is involved, they quite often have a telco background, and think that peering has something to do with SS7. That is, they try to insist that the Internet is really just the same as the voice telephone network, and BGP4 is SS7. The results are often comic.
Immature systems can tolerate inefficiency. Iterated competition results in progressive loss of leeway. Use of IT in economic areas of human enterprise is just the beginning of this process.
What do you think "nexus" means??
Conventional definition: ---------------------------------------------------------------------- n. pl. nexus or nexuses
1. A means of connection; a link or tie: this nexus between New York's... real-estate investors and its... politicians (Wall Street Journal). 2. A connected series or group. 3. The core or center: The real nexus of the money culture [was] Wall Street (Bill Barol). ----------------------------------------------------------------------
As Lewis Carroll tried to make clear a long long time ago, it isn't very useful to conduct arguments by redefining words as you go along.
http://computerworld.com.sg/pcwsg.nsf/0/BFED6DE56B76EA4948256CDE00139250?Ope... Document Regional nexus for GPRS Singapore will be Asia's first neutral Peering Point for GRX (GPRS Roaming Exchange) providers. http://www.pch.net/resources/reference/peering/ipv4_with_pch_rs.html A nexus of fiber, copper, or rights-of-way must exist within or proximal to the user community, and it must be open and accessible to those companies which wish to add to or improve upon those facilities. I conced you the point that nexus might be not a common term of the trade. But it's certainly not my invention, see Google. As such, you could go lighter on sarcasm. It can backfire. -- 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]
On Sun, 11 Apr 2004, Eugen Leitl wrote:
A "tree" as the term is used in mathematics and computer science has a
A tree as the term is used in a human language refers to a shape. Ditto
If you want to participate in technical discussions, discipline yourself to use the relevant language correctly. The word "tree" is commonly used in this business. It has a precise meaning. It refers to an acyclic graph with a single root. ------------------------------------------------------------------- "Tree data structure "From Wikipedia, the free encyclopedia. "In computer science, a tree is a widely-used computer data structure that emulates a tree structure with a set of linked nodes. Each node has zero or more child nodes, which are below it in the tree (in computer science, unlike in nature, trees grow down, not up). The node of which a node is a child is called its parent node. A child has at most one parent; a node without a parent is called the root node (or root). Nodes with no children are called leaf nodes. "In graph theory, a tree is a connected acyclic graph. A rooted tree is such a graph with a vertex singled out as the root. In this case, any two vertices connected by an edge inherit a parent-child relationship. An acyclic graph with multiple connected components or a set of rooted trees is sometimes called a forest." ------------------------------------------------------------------- The term is used because most or all trees in the region where the English language originated are shaped just like that: they have a single trunk which forks into branches which may themselves fork and so on. These branches do not connect back to one another. The Internet doesn't resemble a tree at all. It is characterized by many cross-connections, which form cycles. These are introduced deliberately by network engineers, because tree-like networks are unreliable. That is, when a network engineer sees a tree, his immediate response tends to be to fix the tree by adding cross-connections. If you don't have any cross- connects, then any network failure causes loss of connectivity, a very Bad Thing.
"The geometry on Earth surface is anything but whatever"? Sorry,
Now you're refusing to parse English, too. I'm not going to diagram it for you, look at above cited passage.
I learned how to parse English a long time ago. That is not a sentence in English. I have no idea of what you meant to say.
Look outside the window. Does this look like a finite dimensional metric space to you?
Yep. Most would describe the view as three dimensional. 3 is a finite number. Is there a metric? Certainly. The one worked out by Descartes a long time ago will do, the distance between two points in Cartesian coordinates. When I did a course in finite dimensional metric spaces, most of the initial examples were in three dimensional geometries, like what you see when you look out the window. After a while we progressed to things like distortions in space-time AKA gravity.
Are you familiar with geodesy? Are you familiar with the term geodesic as used by ship captains and pilots? It has nothing whatsoever to do with spacetime curvature. You can't travel nor signal through Earth bulk, so you have to route your signals around the spherical obstacle. One you're sufficiently far removed, it's line of sight in a device cloud (a satellite constellation).
I don't believe that I have ever met a ship captain or pilot who knew what the term "geodesic" meant. (Mind you, I never asked.) It's a term used in mathematics and physics. Given a metric on a space, if the length of a path between two points is minimal, that path is a geodesic. In Euclidean geometry, it's a straight line. On the surface of a sphere, it's a segment of a great circle.
I'm claiming peering arrangement evolve to make optimal use of given physical cabling. This is quick.
As the term is normally used, "peering" is the settlement-free exchange of trafic between autonomous systems (ASNs). "Settlement-free" means that no consideration ($$$) is paid. This has bugger all to do with cabling.
Peered traffic is exchanged over a point. It is frequently called a nexus.
I spent more than seven years running an ISP and in that time set up over 100 peering relationships. Throughout that time I never heard anyone refer to anything as a "nexus". The term _is_ used by marketing types when they are getting rhapsodic. And I have heard it used in political discussions. And in poetry. On the other hand, peered traffic is often exchanged between networks (ASNs) at several different points; these might be thousands of miles apart. Google on BGP and MED.
Peering arrangements generally involve legal departments, and rarely change once inked.
The worse for them. Computers can negotiate, too, and a lot quicker than people.
You may not like legal departments, but this is irrelevant to common practice on the Internet. Peering agreements are legal documents. Most companies have them drawn up by lawyers and they are very rarely changed. (Exceptions? People in the business might remember Agis and Exodus.) Computers are pretty useless in negotiating peering. It usually involves friendly chats over the telephone, sometimes a beer down at the pub.
I conced you the point that nexus might be not a common term of the trade. But it's certainly not my invention, see Google. As such, you could go lighter on sarcasm. It can backfire.
Introducing standard term that you insist be misinterpreted according to your peculiar practice can also waste a great deal of time. It makes more sense to use terms in the normal way and spend your time and energy arguing real issues. I think that your argument was that telecommunications is moving towards a future in which traffic will be evenly distributed over the earth's surface because this is optimal, because a uniform distribution is dictated by physics. I think that you are quite wrong in this, but the argument regarding substance got lost in your insistence that words be used oddly. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
Jim Dixon wrote:
The term is used because most or all trees in the region where the English language originated are shaped just like that: they have a single trunk which forks into branches which may themselves fork and so on. These branches do not connect back to one another.
I believe the real issue here is one of being able to stretch your mind into seeing things from different points of view. This is the reason I brought in the quasi-mystical quote about the sphere whose center is everywhere. To see if you'd be able to go beyond your already rich knowledge and gain new benefit from another way of looking at it. (IMHO, it's important to be able to change POV's at will, it keeps you flexible and able to learn new ways of dealing with data by conversion.) In real life, the roots of a tree resemble it's branches buried underground, in an almost mirror image. A tree that terminates where the trunk meets the ground would fall. The only real tree resembling this, is one where logger's saw was applied. :) So we're already not discussing a real tree. The idealized mathematical definition of a tree doesn't quite a real tree any more than do B-Trees, B+/-Trees, nor red/black trees, or our debated friend, the internet.
The Internet doesn't resemble a tree at all. It is characterized by many cross-connections, which form cycles. These are introduced deliberately by network engineers, because tree-like networks are unreliable.
Of course. It's called redundancy and its goal is to eliminate as many single points of failure as possible. But from the point of view of one node talking to another, these aren't considered, I'll explain why. Firstly, don't confuse cycles with redundancy for high availability. These are two different things. Let's explain why we have multiple connections and what types of these you can expect. There are two common types of multiple connections: A) Two links to the same ISP: In terms of redundancy for the purposes of being fault tolerant, only one of the multiple links is ever used. With most ISP's, when you negotiate a contract for a backup connection, it's with the understanding that you'll only use it when the main one goes down. B) You have multiple connections to different ISP's (possibly with peering contracts, etc.) In this case when a node at your location tries to contact some other node on the internet, it's traffic doesn't go over ALL of your connections - it takes only a single path. [Ok, if your routers are correcting for an outage, then perhaps you'll see different paths being taken, but this is just the routing tables/routers settling or converging.] If both case A and case B, a single node in your location will see the entire internet as a tree with the root of that tree being the default gateway. (i.e. go back to doing traceroutes.) In the case of a multi-homed machine, or machine that participates in routing, it itself becomes the root of the tree. There are other cases but those are rare, and likely flawed. Now on to cycles and the whole reason for this debate: The whole point of many/most routing algorithms is to GET RID OF cycles. After you've done this, you're left with a tree. Loops/cycles are so anathema to the workings of tcp/ip, that one of the fields in IP packets has been added to help eliminate: the TTL. The only reason for a TTL value is to prevent packets that are going around in circles from congesting all the routers involved in the loop. (Only later did traceroute exploit this into helping provide you with a map of where your packets went.) This is why EIGRP, RIP, etc. use various mechanisms to explicitly prevent routing loops (and BGP to aggregate routes.) Routing loops are damage, they are by definition not desirable. At the data link layer (switches/hubs), this is why you want to use the Spanning Tree Protocol. Notice that name: Spanning *TREE* Protocol. After STP is done, you're left with a data link layer ->TREE< - not a cyclical graf. STP is even more important for LAN's than on the internet since there's no TTL on ethernet frames: a single broadcast, were it to be allowed to loop, could saturate your switches to the point of killing your LAN! What all this says to me is that a cycle is a circle, and that failover/ parallel links should be collapsed (and are by routing protocols) to a single link. Once you eliminate cycles, and you do so in real life, you go back to a tree. You only see the alternate paths used when failover or routing errors occur. Yes, I agree with you, if your POV is "The Big Picture" above from space, which includes all links, even the unused redundant ones, it's certainly not a tree. At the same time, I also disagree with you. If your POV is a single host, it sees the internet as a tree. In fact, one of the properties of trees is that you "pick up" any leaf node and designate it as the root. (Doesn't work too well on a B+Tree when you're trying to do searches, but, the result is still a tree - not balanced any longer, but a tree.) :)
On Sun, 11 Apr 2004, sunder wrote:
The term is used because most or all trees in the region where the English language originated are shaped just like that: they have a single trunk which forks into branches which may themselves fork and so on. These branches do not connect back to one another.
I believe the real issue here is one of being able to stretch your mind into seeing things from different points of view. This is the reason I brought in the quasi-mystical quote about the sphere whose center is everywhere.
Someone comes to me and says: "the Internet is a tree". Then he points me at a graph of inter-AS (Autonomous System) connections to illustrate his point. That graph includes all of those seemingly redundant connections that make it _not_ a tree. These seemingly redundant connections are in fact a high proportion of all connections. That is to say, the graph is accurate and his statement wasn't. You can see the Internet in many ways. You can run a single traceroute and see it as a line. You can ping broadcast on your LAN and see it as a chorus line. If you understand what you are looking at, you can run traceroutes and see stable rings: hot potato routing at work, where the packets go out one way and come back another. Then again, I have spoken to hundreds? thousands? of people who think that the Internet _is_ the World Wide Web.
Let's explain why we have multiple connections and what types of these you can expect. There are two common types of multiple connections:
A) Two links to the same ISP: In terms of redundancy for the purposes of being fault tolerant, only one of the multiple links is ever used. With
You don't understand and you are quite wrong. If one AS has more than one link to another AS, there are often very good reasons for it, and both links are used. If network A peers with network B in both Paris and New York, both will generally dump traffic for the other network at the nearest connection. Why? Well, on the one hand, there is no reason to carry packets originating in Paris and destined for a host in Paris all the way to New York. On the other hand, many or most networks employ hot potato routing, meaning that if network A picks up a packet for network B in Paris, it dumps it on network B as soon as it can, to minimize costs, wherever the destination might be. Some networks, concerned with quality of service, adopt the opposite strategy, and carry packets as far as possible within their own network.
most ISP's, when you negotiate a contract for a backup connection, it's with the understanding that you'll only use it when the main one goes down.
I don't think that you have any evidence for this assertion about what characterizes 'most' backup agreements. I do know that most networks regard this sort of statistical information as highly confidential.
B) You have multiple connections to different ISP's (possibly with peering contracts, etc.) In this case when a node at your location tries to contact some other node on the internet, it's traffic doesn't go over ALL of your connections - it takes only a single path. [Ok, if your routers are correcting for an outage, then perhaps you'll see different paths being taken, but this is just the routing tables/routers settling or converging.]
The world is more complicated than this. Much more.
If both case A and case B, a single node in your location will see the entire internet as a tree with the root of that tree being the default gateway. (i.e. go back to doing traceroutes.) In the case of a multi-homed machine, or machine that participates in routing, it itself becomes the root of the tree.
There are tens of thousands of machines on the Internet that don't have a default gateway. Machines that participate in backbone routing have multiple connections and aren't the root of a tree in any normal sense of the word. There is no parent-child relationship between such routers: they are peers. These peers participate in a highly complex graph which dances continuously. The result is that routing has a large stochastic component: if you can understand what you are looking at, you often see traceroutes involving packets jumping sometimes one way, sometimes another. To make things even more difficult to understand, an increasing amount of traffic flows through MPLS tunnels, which are invisible to traceroutes.
Once you eliminate cycles, and you do so in real life, you go back to a tree. You only see the alternate paths used when failover or routing errors occur.
This just isn't true. Hot potato routing is the most easily understood example: traffic goes out one way and back another. It does this because the ASs involved have set their policy that way. Backbone routers have lots of knobs to configure traffic flow. Some of these allow you to throttle it, some allow you to split flows according to traffic type, some allow to to split flows statistically, some allow you to drop packets statistically. And some allow you to ignore pings and traceroutes ;-)
At the same time, I also disagree with you. If your POV is a single host, it sees the internet as a tree.
Sorry. I have spent too many long hours probing the Internet from single hosts to accept this. If you understand what you are looking at, you see something much more complicated than a tree.
In fact, one of the properties of trees is that you "pick up" any leaf node and designate it as the root.
There are different types of trees. Most discussions of 'trees' are about rooted trees, which are directed acyclic graphs with one and only one root. However, all trees are acyclic. The Internet isn't. Of course, most of this discussion revolves around one word: "is". If you said "the Internet _can be seen_ as a tree", few would disagree with you, especially if you allowed for the fact that that tree is continuously changing its shape. But "the Internet _is_ a tree"? That's simply an error. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
On Mon, Apr 12, 2004 at 06:41:14PM +0100, Jim Dixon wrote:
Of course, most of this discussion revolves around one word: "is". If you said "the Internet _can be seen_ as a tree", few would disagree with you, especially if you allowed for the fact that that tree is continuously changing its shape. But "the Internet _is_ a tree"? That's simply an error.
Do I have some 6 connections to my direct neighbours? Like the guy next door, who's on DSL as well? Geographic routing is just that. Once again, you're too caught up in current technology to understand what the fuck I'm talking about. It doesn't matter on the long run. -- 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]
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.
It is a tree. I'll give you a hint. Think of this: "God is like an infinite sphere, whose center is everywhere and circumference nowhere." Nicholas of Cusa. It is a tree, but to see it, you'll need to find the root. The quote above is a hint to where the root is. Replace god with internet, sphere with tree, infinite with 2**32 (at least until it goes to ip6.) So where's the root? Scroll down for the answer. | | | \ / V Did you see it? No??? It's actually right infront of you. Still don't know? Ok then, keep scrolling down. The root of the internet is your own internet connection. Proof: If you were to iterate traceroutes over the entire ip4 space (good luck doing that by the way), and graph the results, you'd get a tree. It's root is your default gateway. :)
On Sat, 10 Apr 2004, sunder 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.
It is a tree. I'll give you a hint. Think of this:
"God is like an infinite sphere, whose center is everywhere and circumference nowhere." Nicholas of Cusa.
Let me give you a hint: a tree is an acyclic graph. The Internet shown in Eugen's pretty pictures is defined by BGP4 peerings between autonomous systems. It is highly cyclic, because everyone wants it that way. As a network, a tree is a delicate structure: any break in links fragments the network. Network engineers spend a lot of time making sure that their networks, and the Internet, are not trees. Multiple peering and transit relationships make the network robust - and cyclic. -- Jim Dixon jdd@dixons.org tel +44 117 982 0786 mobile +44 797 373 7881 http://jxcl.sourceforge.net Java unit test coverage http://xlattice.sourceforge.net p2p communications infrastructure
It's a tree No, it's not a tree I thought we were sort of an autonomous collective! Watery marketers lobbing Powerpoints is no basis for a form of architecture
Network engineers spend a lot of time making sure that their networks, and the Internet, are not trees. Multiple peering and transit relationships make the network robust - and cyclic.
The core of the current Internet routing architecture in the US is a couple of dozen "Tier 1" providers who almost all interconnect with each other, with each pair almost always connected in more than two places (usually an East Coast and a West Coast location plus others.) - Most of the Tier 2 providers are connected to at least two upstreams, either both Tier 1 or a Tier 1 and a Tier 2. - There's no well-defined boundary between Tier 2 and Tier 3, but the Tier 3 types of folks may not be as diverse. - Some big hosting companies are owned by Tier 1 carriers, and may just get connectivity from their parent company, but it usually still has physically diverse connections to diverse switches. - Many other hosting companies are independent of the carriers, and tend to have feeds from multiple carriers (usually multiple Tier 1 for the big players). - Many big end-user companies have multiple large internet feeds from multiple carriers; even small companies with a couple of T1s often try to get some diversity (in which case the ISP run by the local telco is often one of their providers.) - If you want physically diverse access to your building, you usually need to buy at least a couple of T3s - some local telcos will still do diverse T1 access, but most don't, or else they have it in their tariff rate but *your* street doesn't have it. As Jim and others have said, it's extremely not tree-like - we want to maximize the number of careless drunken backhoe drivers it takes to take down our circuits, as well as maximizing the number of equipment failures and operator mistakes it takes, and trying to minimize the damage any problem causes. DNS's namespace is tree-like, but the actual implementation of the DNS name server networks is very forested and meshy. The biggest problems are all at layer 9.
At 3:55 AM -0700 4/11/04, Bill Stewart wrote:
The biggest problems are all at layer 9.
Exactly. And, I would claim, that because of book-entry settlement, the latency thereof, the need to send someone to jail if they lie about a book entry, and the unavailability of bearer transaction settlement, we need lawyers and politicians to effect our network transactions, and the more bandwidth involved, like those between tier 1 interconnections, the more politicians and lawyers you need. At the top of the network lurk the most expensive "switches", again. As I've said before, geodesic networks need geodesic transactions. Book-entry transactions, are, by definition (look at a chart of accounts in a company's books...) tree-like. Cash and bearer transactions are, inherently, geodesic. There are only three parties to a bearer transaction, the underwriter, the buyer and the seller. A book entry transaction requires up to seven participants, in, guess what, a hierarchy, with a single route through the network. Cheers, RAH -- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'
participants (6)
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Bill Stewart -
Eugen Leitl -
Jim Dixon -
Major Variola (ret) -
R. A. Hettinga -
sunder