Via: Improving Internet Telephony Call Quality Using Predictive Relay Selection

Interactive real-time streaming applications such as audio-video conferencing, online gaming and app streaming, place stringent requirements on the network in terms of delay, jitter, and packet loss. Many of these applications inherently involve client-to-client communication, which is particularly challenging since the performance requirements need to be met while traversing the public wide-area network (WAN). This is different from the typical situation of cloud-to-client communication, where the WAN can often be bypassed by moving a communication end-point to a cloud “edge”, close to the client. Can we nevertheless take advantage of cloud resources to improve the performance of real-time client-to-client streaming over the WAN? In this paper, we start by analyzing data from a large VoIP provider whose clients are spread across over 21,000 AS’es and nearly all the countries, to understand the challenges faced by interactive audio streaming in the wild. We find that while inter-AS and international paths exhibit significantly worse performance than intra-AS and domestic paths, the pattern of poor performance is nevertheless quite scattered, both temporally and spatially. So any effort to improve performance would have to be fine-grained and dynamic. Then, we turn to the idea of overlay routing, but in the context of the well-provisioned, managed network of a cloud provider rather than peer-to-peer as has been considered in past work. Such a network typically has a global footprint and peers with a large number of network providers. When the performance of a call via the direct path is predicted to be poor, the call traffic could be directed to enter the managed network close to one end point and exit it close to the other end point, thereby avoiding wide-area communication over the public Internet. We present and evaluate data-driven techniques to deciding whether to relay a call through the managed network and if so how to pick the ingress and egress relays to maximize performance, all while operating within a budget for relaying calls via the managed overlay network. We show that call performance can potentially improve by 40%-80% on average, with our techniques closely matching it.