QoS routing computation with path caching: a framework and network performance

We present a framework for QoS routing computation with path caching. The framework has three phases to allow different levels of information to be processed at different timescales to effectively meet QoS requirement of a newly arrived flow. Path caching is introduced in the first phase to allow selection and filtering in subsequent phases. We describe several routing schemes that can fit into this framework. Through simulation results, we show where and how the benefit of path caching can be exploited depending on the number of paths cached, and when to invoke other controls. Our results show that QoS routing by itself cannot improve the network and/or service performance unless controls such as trunk reservation and source-based admission control are also activated. The invocation of these functions can also allow maximum benefit from the path caching framework.