Vendredi 25 septembre 2015 à 11h, salle 24-25/405
Message routing is a central activity in any interconnection network. Route efficiency and memory requirements are two major central parameters in the design of a routing scheme. Routing along short paths is clearly desirable, and the storage of the routing information at each node must also be limited to allow quick routing decision, fast update, and scalability. There is a trade-off between the route efficiency (measured in terms of stretch) and the memory requirements (measured by the size of the routing tables). For a n nodes network, the classical shortest path routing scheme achieve stretch 1 with n entries per node (router). Compact routing techniques offer different tradeoffs by allowing routing detours. It is known that in order to guaranty that every route has a stretch strictly lower than 2k+1 the routing tables must have size of order n^1/k at least. Is it actually possible to design routing schemes that attain these lower bounds? This is the question I will answer during my talk, explaining in the mean time the main algorithmic ideas used to achieve the currently best known trade-offs. Finally I’ll also introduce the more specific problem of compact routing in « internet-like » graphs.