Minimizing packet delay (or packet latency, as it is often called) is an important goal in modern telecommunication networks. In a network with given physical and topological characteristics, uneven distribution of traffic between nodes may result in parts of the network being underutilized while other parts may experience congestion and its related effect of higher delays, and even packet loss if buffers become overloaded. Overload results in longer queuing delays, which are a major, if not the major, source of packet delay. Internet nodes typically route based on a single best (shortest) path without taking into account link occupancy and without taking full advantage of all available network resources. So a method for improving network performance is to allow nodes to use multiple paths to route packets to a given destination. In this research project the main objective is to find the best algorithm that, applied to a multicommodity network, produces multipath flow assignments that minimize the maximum cross-network delay. The motivation for this objective is the tighter requirements for quality of service coming from real-time streaming services, such as voice and video, that restrict the maximum source-destination packet delay. An analytical approach based on Lagrange Multipliers was used, leading to an iterative algorithm that can be proved to converge to the optimal path and flow configuration. From that algorithm a simplified heuristic algorithm was derived that achieves results close to optimal. Another heuristic, but more intuitive, algorithm was also investigated and was found to also offer good results and to be computationally efficient. The two heuristic algorithms were simulated using Java programs and. as a benchmark, the single path algorithm that is commonly used in the Internet was also simulated in Java. Performance comparisons for the three types of simulations are also provided. For a more realistic evaluation, the intuitive heuristic algorithm was also simulated in the NS-3 simulation environment, an industry standard widely used in the academic world. For the NS-3 simulation a distributed routing protocol that implements the maximum delay minimization algorithms without centralized control, was designed.
|School:||Illinois Institute of Technology|
|Department:||Electrical and Computer Engineering|
|School Location:||United States -- Illinois|
|Source:||DAI-B 75/02(E), Dissertation Abstracts International|
|Keywords:||Multipath connections, Packet delay, Path delay, Routing protocol|
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