Functional Topology of Networks

PhDIn order to utilise network resources efficiently, we need a strong knowledge of how the resources are shared and provisioned. However,this information is often unavailable due to the complexity of modern networks, the restrictive access to information describing their configurations and accuracy/reliability issues regarding information provisioning methods. Here, we propose the concept of functional topologies tod educe how resources are shared between different traffic flows. A functional topology describes the dependencies between traffic flows as a graph of interactions; this is in contrast to typical network graphs that model the physical connections between network components (routers and hosts). Unlike other work relying on in-network data, this topology is constructed solely at end hosts by measuring interdependencies of traffic flows via cross-correlation analysis. In order to measure the complete sets of interdependencies of traffic flows, different time intervals are used for sampling time series data. It is shown that these time intervals are related to maximum delays of traffic flows in network. The results of cross-correlation analysis are validated using well-known inverse participation ratio (IPR). As a part of the validation process, the results are analysed and compared with dominant/important flows of the network obtained by a new technique that uses eigendecomposition and spanning tree algorithm. The methodology of measuring interdependencies of traffic flows is validated and evaluated using real world data from a sensor network,as well as detailed simulation modelling different network topologies e.g. local area network. All the dependency measurements of traffic flow results are fed into a novel algorithm to construct functional topology of the network. Result shows that the algorithm constructs accurate functional topology of the network. Functional topology simplifies network topology by considering only nodes that create dependencies among traffic flows. With the help of this topology, end hosts can gain insight into resource provisioning of a network without requiring ISP assistance