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Workshop PRIXNET Distributed Virtual Circuit Switching protocol with auction pricing Loubna ECHABBI Dominique BARTH Laboratoire PRISM
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Workshop PRIXNET Framework Virtuel circuit switching networks. Goal: Ressource allocation to satisfy some QoS. How : connection establishment. O D 3 4 2 5 3
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Workshop PRIXNET Conflict : Congestion in a router Definition: the demand is greater than the available resource. Question : which criterions to choose accepted requests. Maximize the number of accepted requests. Minimize the remaining bandwidth. for more fairness: Use auctions to charge accepted requests some congestion cost. These prices can be used to compute routing tables or in the service pricing.
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Workshop PRIXNET Auctions : local approach At each router we have the following information: A set of requests (budget, demand, destination..) A set of outgoing links ( capacities ) A set of links obtained from the routing table which link each request to possible outgoing links. Two types of routing are studied : Deterministic routing : 1 destination= 1 outgoing link. Non deterministic routing : 1 destination= n outgoing links
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Workshop PRIXNET Auctions: first model Requests submit their offer. The router chooses a combination of traffic that maximizes its profit. The non accepted requests increase their offer (by one unit). The stopping criteria : non accepted requests cannot increase their offer anymore. At each step the problem is NP-complete (even in the deterministic case: contains the knapsack problem). Auctions final result is difficult to be characterized.
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Workshop PRIXNET Auctions : second model 2 4 4 3 3 1 2 3 * 1 4 3 3 1 * 3 * 1 3 4 1 4 4 3 3 1 2 3 1 The main idea: each link fixes its cost.
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Workshop PRIXNET Second model : Deterministic case Auctions on different links are independent At each step the problem is polynomial. The auction’s final result can be polynomialy obtained by sorting the requests in a decreasing order and accepting them in this order while keeping the capacity constraint held. Note: When congestion occurs, the accepted requests are charged the first non accepted bid, else the cost is null.
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Workshop PRIXNET Second model: non deterministic case. Definition: The set of stable links, at a given step, is the set of links such that all requests that can be routed at least on one element of this set, is indeed accepted on a link in that set. Auction on different links are not independent. 2 3 2 2 2 3 3 4
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Workshop PRIXNET Second model: non deterministic case 4 3 3 1 2 1 2 1 3 1 2 1 3 4 3 3 1 2 1 2 1 3 1 2 1 3 2 3 2 2 3 4 3 3 1 2 * 2 4 3 3 1 2 * 2 2 3 1 3 1 2
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Workshop PRIXNET Second model: non deterministic case Conjecture: the stable link maximization problem is NP- Complete. Process: At each step, we maximize the number of stable links. At the end of each step, non stable links increase their offer and eliminate requests that cannot bargain. Property: With any configuration that maximizes the set of stable links, stable links are the same.
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Workshop PRIXNET A heuristic idea 63 2 3 1 1 1 5 4 3 2 1 2 5 * 2 0 * 4 3
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Workshop PRIXNET Previous work and perspectives Previous work: Complexity study. Implementation of the exact problem in Cplex. Implementation of a simulator with the virtual circuit protocol layered on a grid network. Current work: A comparison between the exact and the heuristic methods using the simulator. Test of different auction strategies.
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