| Popis: |
Optimal QoS path provisioning of coexisted and aggregated traffic in networks is still demanding problem. All traffic flows in a domain are distributed among LSPs (Label Switching Path) related to service classes, but the congestion problem of concurrent flows (traversing the network simultaneously) can appear. For LSP creation the IGP (Interior Getaway Protocol) uses simple on-line routing algorithms (e.g. OSPFS, IS-IS) based on shortest path methodology. In the presence of premium traffic where some links may be reserved for certain traffic classes or for particular set of users it becomes insufficient technique. On other hand, constraint based explicit routing (CR) based on IGP metric ensures traffic engineering (TE) capabilities. It may find a longer but lightly loaded path better than the heavily loaded shortest path. In this paper a new approach to explicit constraint-based routing is proposed. LSP can be pre-computed much earlier, possibly during SLA (Service Level Agreement) negotiation process. It could be a very good solution for congestion avoidance and for better load-balancing purpose where links are running close to capacity. To be acceptable for real applications such complicated routing algorithm can be significantly improved. Further improvements through heuristic approach are made and comparisons of results are discussed. |
