Enhancing Fast TCP’s Performance Using Single TCP Connection for Parallel Traffic Flows to Prevent Head-of-Line Blocking

Hypertext Transfer Protocol-2 (HTTP/2) partially resolved the problem of Head-of-Line Blocking (HoLB) by multiplexing independent messages at the application layer. This enables simultaneous transmission of multiple requests over the same connection independently. However, this technique becomes ineffective when packet loss occurs in the Transmission Control Protocol (TCP) flow in which case all the independent streams are blocked until the retransmission of the lost packet; this problem is known as HoLB at TCP-level. The problem arises because the underlying TCP does not differentiate between independent messages/streams from application layer protocol. This study proposes a multistream framework for Fast TCP to support multiple independent messages/streams of the application. The proposed framework uses separate flows, buffers, and segments for each independent stream, and interleaves these segments over a single TCP connection. It makes TCP compatible with HTTP/2, reduces data delivery latency between transport and application layer, and alleviates head-of-line blocking. We implemented this framework in Fast TCP and carried out a simulation-based comparison between Multistream Fast TCP (MFast TCP) and Stream Control Transmission Protocol (SCTP). Our results show that MFast TCP significantly improved performance over SCTP in the event of HoLB.