Browsing by Author "Robertson, William"

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    COMPARING A NOVEL QOS ROUTING ALGORITHM TO STANDARD
    (2010-11-19T16:42:41Z) Sivakumar, Shyamala; Phillips, Bill; Robertson, William; Goodridge S., Wayne
    The problem of finding QoS paths involving several combinations of network metrics is NP-complete. This motivates the use of heuristic approaches for finding feasible QoS paths. Many constraint based routing algorithms find QoSpaths by first pruning resources that do not satish the requirements of the trafic flow and then running a shortest path algorithm on the residual graph. This approach results in a QoS path that biases thefirst metric used in the search process. In addition, it can be shown that this approach may not alwaysfind the optimal path. Our research introduces a QoS routing algorithm that is based on a decision support system that is used to compute QoS paths. We demonstrate the feasibility of this approach by comparing it to standard pruning techniques.
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    Heuristic Constraint-Path Routing Decision System
    (IEEE Computer Society, 2005-05-18) Sivakumar, Shyamala; Phillips, William J.; Robertson, William; Goodridge, Wayne
    Heuristic QoS algorithms under strict constraints perform poorly in terms of finding a path that is suitable for a user?s QoS needs - the multiple constraint path problem (MCP). Exact QoS algorithms, on the other hand, guarantee that a path satisfying user needs would be found and o..er a more realistic approach for solving the MCP problem in view of the fact that the NP-complete character of graphs are not common in real networks. This fact has driven approaches like the SAMCRA and A*prune algorithms. However, these algorithms still have very high running times relative to heuristic approaches. When QoS routing algorithms are used in online Tra..c Engineering (TE) environments it may be necessary to route thousands of traffic flows each minute. Exact algorithms simply cannot work in such environments. We propose a heuristic algorithm that is suitable for working in an online TE environment. Simulations show that this algorithm produce high success rates in terms of finding suitable constraint paths for user flows while at the same time having execution times comparable to another heuristic based algorithms.