A Concurrent Multipath TCP and Its Markov Model

Concurrent Multipath Transport (CMT) has been of increasing interest recently for aggregating bandwidth, balancing load, and increasing reliability. In this paper we propose a concurrent multipath Transport Control Protocol (cmpTCP), which is an extension of TCP New Reno and Steam Control Transmission Protocol (SCTP). The proposed cmpTCP has been implemented by altering and extending library-based open-source for SCTP. The proposed cmpTCP manages transport control parameters of all paths simultaneously; a scheduler concurrently dispatches packets over all the paths from a common transmission queue. However, one virtual retransmission queue is maintained for each path, and the receiver sends acknowledgment for a packet on the same path on which the packet is received. A Markov model for estimation of expected window size of each path has been proposed. Next, the proposed model has been utilized to derive an expression for computing average data transmission rate when the proposed cmpTCP is used. To validate performance of the proposed model, two host computers were connected through two independent network emulators. Each network emulator runs on a separate computer, and the network parameters are adjusted independently. We used our cmpTCP for transferring files from one host to the other. Comparison of experimental results with model predicted results shows excellent agreement.