Using delay-gradient TCP for multimedia-friendly ‘background’ transport in home networks

Home networks are seeing increased deployment of Wireless LAN (WiFi) links between conventional, gigabit/second wired Ethernet segments. This means an increasing number of internal bottlenecks, even as home networks are also expected to support latency-sensitive applications, regular TCP flows and an emerging class of low-priority, time-insensitive `background' TCP flows. This paper explores the novel use of CDG v0.1 (a delay-gradient TCP) for such background TCP connections in home networks. We show a CDG flow induces latencies of only tens of milliseconds regardless of the bottleneck's internal buffer size (useful when coexisting with latency-sensitive traffic) while achieving a significant fraction of spare link capacity. We also show CDG does not gratuitously steal capacity from commonly deployed “foreground” TCPs such as CUBIC and NewReno.