The two markers system for TCP and UDP flows in a differentiated services network

There are two cruxes of issues identified in differentiated services (Diffserv) networks: one is TCP dynamics, and the other is the interaction of TCP and UDP flows for assured forwarding per hop behaviour (PHB). The saw-tooth like behaviours of TCP prevent each flow from realising its target rate, and congestion insensitive flows such as UDP penalise for TCP flows when both are given same AF class. Therefore, we argue the use of TCP-friendly building blocks and fairness modules in the Diffserv architecture regarding these issues, and propose two markers system (TMS) that is able to properly mark packets and fairly share the bandwidth to each flow for their targeted sending rates. TMS has two marking modules that are placed on the source and the edge of a Diffserv network, respectively. For sources of the network, TCP-source making module plays important roles of reducing TCP impacts in the assured services and adequately marking packets. Next, in the edge of the network, the edge-embedded marking module conducts new fairness policy based on the marking rate of flows from sources, so-called 'marking rate-based fairness'. Finally, we present simulation results to illustrate the effectiveness of TMS scheme over several parameters. That is, TMS alleviates TCP impacts over assured service and the issue of unfair distribution of excess bandwidth in an over-provisioned networks as well as unfair degradation in an under-provisioned network for TCP and UDP flows.