On open shortest path first related network optimisation problems
The paper deals with flow allocation problems in IP networks using open shortest path first (OSPF) routing. Its main purpose is to discuss and propose methods for finding settlements of OSPF link weight system realising the assumed demand pattern for the given network resources (links capacities). Such settlements can result in a significantly better network performance, as compared with the simplified weight setting heuristics typically used nowadays. Although the configuration of the link weight system is primarily done in the network planning phase, still additional re-optimisations are feasible, and in fact essential, in order to cope with major changes in traffic conditions and with major resources failures and rearrangements. The paper formulates a relevant OSPF routing optimisation problem, proves its NP-completeness, and discusses possible heuristic approaches and related optimisation methods for solving it. Two basic approaches are considered (the direct approach and the two-phase approach) and the resulting optimisation algorithms are presented. The considerations are illustrated with numerical results.
network optimisation ospf traffic engineering multicommodity flows