Martin T. Flack

A case for faster mobile web in cellular IPv6 networks

The transition to IPv6 cellular networks creates uncertainty for content providers (CPs) and content delivery networks (CDNs) of whether and how to follow suit. Do CPs that update their CDN contracts to allow IPv6 hosting achieve better, or worse performance in mobile networks? Should CDNs continue to host mobile content over IPv4 networks, or persuade to their CP customers the performance benefits of IPv6 content delivery? In this paper we answer these questions through a comprehensive comparison of IPv4 and IPv6 mobile Web performance in cellular networks in the US from the point of view of Akamais content delivery infrastructure. Our data show that IPv6 hosting outperforms legacy IPv4 paths in mobile Web. Our analysis leads to clear recommendations for CPs to transition to IPv6-hosted mobile Web. Finally, we propose new mechanisms, through which CDNs can safely transition mobile content to IPv6-enabled servers for improved content delivery.

Detecting Cellular Middleboxes Using Passive Measurement Techniques

The Transmission Control Protocol (TCP) follows the end-to-end principle – when a client establishes a connection with a server, the connection is only shared by two physical machines, the client and the server. In current cellular networks, a myriad of middleboxes disregard the end-to-end principle to enable network operators to deploy services such as content caching, compression, and protocol optimization to improve end-to-end network performance. If server operators remain unaware of such middleboxes, TCP connections may not be optimized specifically for middleboxes and instead are optimized for mobile devices. We argue that without costly active measurement, it remains challenging for server operators to reliably detect the presence of middleboxes that split TCP connections. In this paper, we present three techniques (based on latency, loss, and characteristics of TCP SYN packets) for server operators to passively identify Connection Terminating Proxies (CTPs) in cellular networks, with the goal to optimize TCP connections for faster content delivery. Using TCP and HTTP logs recorded by Content Delivery Network (CDN) servers, we demonstrate that our passive techniques are as reliable and accurate as active techniques in detecting CTPs deployed in cellular networks worldwide.

HTTP/2 performance in cellular networks: poster

HTTP/2 (h2) was standardized in 2015 as an improvement to HTTP/1.1 (h1) to achieve faster webpage load times (PLTs) [5]. Previous studies have shown both improvement and degradation in PLT when using h2 with respect to h1 [6, 8]. The disagreement about h2 performance from these studies motivates further investigation as to whether and under what conditions h2 brings the performance benefits that were originally envisioned [5].

Measuring What is Not Ours: A Tale of 3^{\text {rd}} Party Performance

Content Providers make use of, so called \({\textit{3}}^{{ rd}}~{{ Party}}\) (\({\textit{3P}}\)) services, to attract large user bases to their websites, track user activities and interests, or to serve advertisements. In this paper, we perform an extensive investigation on how much such \({\textit{3Ps}}\) impact the Web performance in mobile and wired last-mile networks. We develop a new Web performance metric, the \(\mathtt{3}^\mathtt{rd}~\mathtt{Party~Trailing~Ratio}\), to represent the fraction of the critical path of the webpage load process that comprises of only \({\textit{3P}}\) downloads. Our results show that \({\textit{3Ps}}\) inflate the webpage load time (PLT) by as much as 50% in the extreme case. Using URL rewriting to redirect the downloads of \({\textit{3P}}\) assets on \({\textit{1}}^{\textit{st}}~{\textit{Party}}\) infrastructure, we demonstrate speedups in PLTs by as much as 25%.