The current TCP or its variants are challenged with a number performance related issues when deployed in high Bandwidth-Delay Products, BDP, Networks such as the grid. Prominent among these challenging performance issues is poor network resource allocation which leads to under-utilisation of the grid. This thesis focuses on the development of a novel transmission control protocol which allocates network resource optimally whenever the Bandwidth-Delay Products are high typical in the grid. The thesis presents an congestion avoidance approach which is based on a link"s available bandwidth. To achieve the research goal, the problem of a link"s resource allocation, in high Bandwidth-Delay Products Networks, was analysed, defined and expressed as an optimisation problem with the link"s available bandwidth as a solution to the optimisation problem. To formulate an estimation scheme for the link"s available bandwidth, fluid mechanics and graph theory were employed. An algorithm was designed for the scheme and validation done in Matlab7.0 and ns-2 packet-level simulation tool.