Introduction to Quality of Service Routing Approaches and Algorithms Technical Seminar:

Now-a-days so many applications are there in the internet that need service guarantee in order to maintain the functionality. So far there were no preferences to traffic; internet has followed best effort service. But now, the applications need the service guarantee, to provide this we need a system which provides these kinds of guarantees.

Quality of Service includes some mechanisms and provides such guarantees. QoS considers hop count and doesn’t follow shortest path routing. QoS routing is a routing scheme, under which paths for flows would be determined based on some knowledge of Resource availability in the network as well as the QoS requirements of the flow. 


            The objectives of QoS are based on the information about network state and resource availability. These are as follows

  • Dynamic determination of feasible paths.
  • Optimization of resource usage.
  • Graceful performance degradation. 

Routing algorithms

            We have several problems in QoS routing and we can solve these problems using some algorithms. The two complex problems are MCOP (Multi-Constrained Optimal Path routing problem) and MCP (Multi-Constrained Path routing problem).these can be solved by heuristic approaches. The algorithms that are for the optimization problem MCOP can easily solve also the MCP problem by just checking if the optimal path is feasible with regard to the given constraints. For solving the MCP problem we have several algorithms. Those are Chen and Nahrstedt’s algorithm, Jaffe’s algorithm, Tunable Accuracy Multiple Constraints Routing Algorithm, Iwata’s algorithm, Randomized algorithm.

Routing strategies and approaches:

            QoS routing algorithms are divided into 3 broad classes based on the different tasks done by the QoS routing. Those are i) Source routing ii) Distributed routing iii) Hierarchical routing.

            QoS routing is more popular now because of OSPF protocol.Qospf uses three metrics: Available bandwidth, Propagation delay, Hop count

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