Heiner
Thanks. re your first para - personally I find it very useful to understand what a protocol is trying to do at a high level and why - before reading all the detail. Let me see if I understand your approach: - A node's address is simply its geographic location [based on latitude/longitude]. - The topology is hierarchical & follows the addressing. Geographic-based routing is an interesting idea and there has been some study of it in the ad hoc community I believe. Couple of questions: - Would any policy control be possible? eg to route through a particular higher level network that you have a commercial deal with. How about TE & multihoming? All these things would seem to me to make it more problematic to enforce 'topology must follow geography'. in the context of a global network, would it mean there was only one network? - how would failures be dealt with? Can you discover & swap to and alternative path? (this would then mean that topology didn't follow geography) - could you handle mobile nodes and networks? sorry if I've completely misunderstood it best wishes, Phil Eardley -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: 09 November 2007 11:54 To: [email protected] Subject: [RRG] Topology that follows addressing Let meaddress just that particular NIRA-objective which this mailinglist's discussion is all about, its design and yes, also soon, the hereby needed algorithmic technology as to compute consistently viewed hierarchical topologies. For that computation only a minor enhancement of the Dijkstra is required, but not the entire All Links Spanning Tree (ALST). But step by step. Prior contributing this small though important puzzle as to show the HOW, I think it's appropriate to show at first WHAT shall be accomplished as well as WHY this protocol development will get us out of the BGP-trap or better said aggregation-trap (an imaginary world-wide OSPF would have the same problems). WHAT:The goal is that each router aquires a hierarchical network view, where the current router is surrounded by a network of strict links, which is surrounded by a network of looser ... and looser links. For proper understand WHY so, let me give the following example: Imagine to be at some street junction in Munich, Germany, and you want to get to Sausolito. You have available road maps, for Munich, Bavaria, Germany, Europe and a world map which e.g. contains only 4 US-cities: New York, Chicago, L.A., Miami. But none of your maps shows Sausolito !!! Here, BGP would give up! But let's assume, you also know the geographical coordinates of Sausolito as well as of all nodes of all your nodes on your maps.( 1 degree precision is enough, no minute or second precision is required.). Let's also assume you can by some procedure combine all your maps to a single map whereby your closer zoomed available map information replaces the respective part in the less zoomed map. You may find out that L.A. is closest to your destination and use the L.A. node as the destination node for determining the best next hop - here to the next street in Munich towards the Munich airport. Later, you may arrive in NY, and your current country map would also show San Francisco, but still not Sausolito.So you would make the best next hop being bound to S.F. Whenever you arrive in California, you may also see Sausolito on your current state map and determine the best next hop bound to Sausolito. However, as soon as you have reached a router which has the same geographical coordinates like your destination, this kind of information cannot help you any further. Yes from now on you need guidance based on aggregated prefix information as to determine the proper destination node on your map as we are used to. So prefix propagation can be limited to a 1-degree-square. Note, how powerful the"<=" operator was, when L.A. was selected, compared to "==". Mathematical analogy: If you want to find out whether the real number x is between 0 and 1 you don't have to compare x with all real numbers in this interval. Now the big thing is to build the proper hierarchical network, i.e. the combined topology of the various maps of different zoom. Each loose link must have the right length (weight) ! There must be a clear understanding which 1-degree-squares would be contained within which more upper map. This is subject to "well-known" standardization information. Although the borders should be determined by clean longitude/latitude values and not by political areas like counties, states, countries, continents, let me, for better understanding, use such political terms by the following. Example: A state map shall be built based on all county maps thereof. Each county node router computes the (same identical) county's contribution for this state map, i.e that set of loose links by which it shall be represented in the next upper topology. Hereby it is sufficient that each node of the county knows all those county nodes that shall show up in the state map. This information needs to be exchanged across the borders of neighboring counties of the same state. Not of different states; that would be required in the next recursion cycle. The process is similar to forming a PNNI hierarchy. Like there we would have to deal with uplinks (for combining maps of different zoom) and hierarchical horizontal links, but there are some important differences. An uplink is not the aggregation of a group of border-to-border physical links.Instead its upper end is some representative node of the neighboring county. Instead of the inmature Logical Group Node Representation with spokes and nucleus etc, we would have well-computed representative topologies, in the precisely same manner as when we have road maps for cities, counties, states, countries, continents. If DNS-lookup not only provided the destination IPv4-address but also the longitude/latitude information, and if we computed for each visible node the best next hop, which includes each visible hierarchically upper node, then we could place the best next hop info into a matrix with 360 x 360 elements, and could retrieve it by means of a single access (at least in case of hierarchically upper dest. nodes) Yesterday I received the Internet Journal with contributions about the IPv4 address depletion. Maybe IPv4 addresses have only to be unique 1-degree-square-wide rather than world-wide ?! It may of course be up to the ID-utilization (besides the LOC-utilization), but eventually this solution may also avoid this depletion dilemma. LISP-CONS: Look, there is no political quarrel about the proper allocation of longitudes/latitudes. They are already properly positioned and do not need any dissemination process. By taking geographical coordinates also as address info, then it is appropriate to speak of building some (hierarchical) topology that follows addressing :-) Routing churn: You will see, a loose link like Chicago---L.A. would only go down in case of a power black out throughout the western part of the USA. Hence the looser the link, the less the churn. Rome was not built in one day. Nor this concept. It may take some time for being developed. But it has immense beneficial objectives, which really can be accomplished. Heiner
