An enhanced marking strategy for explicit congestion notification in the Internet

A window-based flow control is a sort of feedback-based congestion control mechanism, and has been widely used in current TCP/IP networks. In the feedback-based congestion control, feedback delay of the congestion information from the bottleneck node is one of the important elements that affects performance. Recently, the use of an explicit congestion notification (ECN) mechanism, as congestion indication from the network to source hosts, has been actively discussed in the IETF. We propose an enhanced marking strategy for ECN that can reduce the congestion information transfer delay of a router in multiple-hop network environments. At a transit router, the proposed method relays the congestion experienced (CE) bit contained in an incoming IP packet to the head-of-line packet with a corresponding flow which is waiting for transmission in the output buffer. Simulation results showed that ECN with the proposed mark-relay strategy produced a superior performance in terms of throughput and fairness between TCP flows.