Achieving end-to-end throughput guarantee for TCP flows in a differentiated services network

A challenge for the differentiated services (DS) architecture is how to simultaneously provide end-to-end assured service (AS) for transport control protocol (TCP) sessions and the best-effort service traffic, based on a single queue management. Our research results show that both intradomain and interdomain best-effort traffic can have an adverse impact on the interdomain TCP traffic. This paper proposes a technique to achieve the desired end-to-end throughput guarantee for TCP sessions. The proposed technique is composed of a series of measures which includes: (a) a path pinning mechanism for AS allowing aggregated bandwidth reservation for AS at each intermediate router in the forwarding path, (b) a packet marking strategy, (c) a dropping policy, (d) an adaptive dropping-threshold calculation method for queue management based on aggregated reserved bandwidth and real-time traffic measurement. The simulation results demonstrate that with this technique, a high end-to-end service assurance can be achieved for the TCP traffic, while a reasonably high throughput for best-effort traffic is maintained.