Amphis: Rearchitecturing Congestion Control for Capturing Internet Application Variety

TCP was designed to provide stream-oriented communication service for bulk data transfer applications (e.g., FTP and Email). With four-decade development, Internet applications have undergone significant changes, which now involve highly dynamic traffic pattern and message-oriented communication paradigm. However, the impact of this substantial evolution on congestion control (CC) has not been fully studied. Most of the network transports today still make the long-held assumption about application traffic, i.e., a byte stream with an unlimited data arrival rate. In this paper, we demonstrate, through both analyses and experiments, that the emerging traffic dynamics and message-level data structure have huge impacts on the correctness and effectiveness of CC, but none of the existing solutions treats these two characteristics appropriately. Therefore, we present Amphis, a new CC framework that re-architects the current pure network-oriented design into a dual-control architecture, which combines application-coordinated control and network-oriented control. Amphis contains two novel ideas, i.e., pattern-driven proactive probing for handling traffic dynamics and message-driven adaptive optimization for optimizing message transmission performance. Our preliminary results show that Amphis holds great promise in terms of accurate bandwidth estimation under dynamic traffic conditions and effective data transfer at message granularity.