On Enhancing Delay SLAs in TCP Networks Through Joint Routing and Transport Assistant Deployment

The Transport Control Protocol has long been the primary transport protocol for applications requiring performance and reliability over the Internet. Unfortunately, due to its retransmission mechanism, TCP incurs high packet delivery delays when segments are lost. To address this issue, previous research proposed to use a novel network function, namely Transport Assistant, deployed within the network to cache and retransmit lost packets, thus reducing retransmission delays. In this paper, we propose to jointly route the flows and deploy TAs in order to minimize packet delivery delays in best-effort networks (scenario 1) or to satisfy delay-based Service Level Agreements in QoS-based networks (scenario 2). We hence formulate the joint routing and TA deployment problem as Integer Linear Program for the two scenarios and propose a heuristic solution for large-scale instances of the problem. Through extensive simulations, we demonstrate the benefits of performing joint routing flows and TA deployment in reducing packet delivery delays (up to 16.4%) while minimizing deployment costs (up to 60.98%).