Architecture, Implementation, and Evaluation of a Concurrent Multi-path Real-time Transport Control Protocol

Abstract

Current multimedia applications utilize a combination of real-time transport protocol (RTP) and user datagram protocol (UDP) for transmitting real-time streams across the network. Bandwidth aggregation over multiple paths for improved real-time stream transmission can be achieved using either a combination of multi-flow RTP (MRTP) and UDP, or various adaptations of Partial reliability (PR) extension of SCTP (SCTP-PR). However, they are not really useful for balancing load on the multiple paths. The receiving end of these protocols can neither identify late arriving packets nor notify the sender about them. The novel concurrent multi-path real-time transmission control protocol (cmpRTCP) proposed, implemented, and evaluated in this work not only overcomes the problems faced by existing multi-path protocols, but also preserves the novel design and implementation features of the recently proposed cmpTCP. This protocol which has a congestion controller and a packet scheduler embedded in its core, intelligently exploits the availability of multiple paths between multi-homed hosts for concurrent transmission and showcases the ability of (i) remaining TCP-friendly while aggregating bandwidth, (ii) balancing load across paths by scheduling more packets on less congested paths, (iii) increasing end-to-end connection reliability by using multiple paths and (iv) improving QoS at the receiving end by scheduling more packets on better paths.