Can API-RCP be TCP friendly with RED?

TCP is widely implemented for congestion control in current IP networks. As the network bandwidth increases, TCP becomes oscillatory and prone to instability, regardless of the queuing scheme. As a rate-based control scheme, XCP was proposed to obtain high link utilization in high bandwidth-delay product networks, while maintaining small queue size in the routers. XCP explicit feedbacks the congestion information in the bottleneck link to the source, and brings a flurry of research interests recently. However, XCP cannot settle to zero steady-state error due to the capacity estimation error, and may lead to arbitrarily low link utilization. Using solid control theoretical analysis and design, API-RCP has solved the potential problems of XCP successfully. Furthermore, API-RCP has simpler structure for real-time implementation. Due to its satisfactory transient network performance and its stability robustness to the dramatic change of the network traffic, API-RCP is a promising algorithm for practical implementation. Why can API-RCP solve the modeling deficiency of XCP? Can API-RCP be TCP friendly with TCP/RED (the current dominant congestion control mechanism in the Internet) in the same router? To answer these two questions, we have made control theoretical comparison of API-RCP with XCP and run OPNET simulation when the APIRCP and TCP/RED co-exist in the same router.