The Transport Control Protocol has long been the primary transport protocol for applications requiring performance and reliability over the Internet. Unfortunately, due 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%).

翻译：传输控制协议长期以来一直是互联网上对性能和可靠性有要求的应用的主要传输协议。然而，由于其重传机制，TCP在数据段丢失时会导致较高的数据包交付延迟。为解决这一问题，先前研究提出使用一种新颖的网络功能，即传输助手，部署在网络内以缓存和重传丢失的数据包，从而减少重传延迟。本文中，我们提出联合路由流并部署TAs，以在尽力而为网络中最小化数据包交付延迟（场景1），或在基于QoS的网络中满足基于延迟的服务等级协议（场景2）。因此，我们将两个场景下的联合路由与TA部署问题建模为整数线性规划，并为大规模实例提出了一种启发式解决方案。通过广泛模拟，我们证明了联合路由流与TA部署在减少数据包交付延迟（高达16.4%）的同时最小化部署成本（高达60.98%）方面的优势。