arXiv subjects

Tanya Shreedhar

Publications and source records attributed to Tanya Shreedhar.

16 recordsLinked to original sources

arXiv2026

Media-over-Multipath-QUIC for Realtime Video Applications

Multipath transports place a client's WiFi, cellular, and satellite networks under one connection, yet real-time video gains little from them. The scheduler that assigns packets to paths sees only bytes, so it cannot tell a keyframe that anchors a second of video from an enhancement frame whose loss costs one image. We show that the limiting factor is not a shortage of path diversity but the absence of a channel through which the application can name what the transport cannot see. Media over QUIC Transport (MoQT), already deployed on production CDNs, carries media as named Objects, and relays forward each Object's metadata without interpreting it. The knowledge the scheduler lacks therefore already flows through the subscriber's relay. We present MoMQ, a MoQT extension that turns this metadata into path decisions. Applications and relay operators install declarative rules at the edge relay that match Object metadata and express delivery preferences against labeled paths. The relay evaluates the rules mechanically, so it acts on video semantics while containing no video logic. On a live testbed spanning Starlink and WiFi, four rules cut P99.9 frame completion time from 384.7 ms under the best transport-only scheduler to 114.1 ms and reduce the required playback buffer by 61.5%. MoMQ is the only configuration that meets the 150 ms interactive latency target. Across relays in two countries and subscribers on two continents, the same rules apply unchanged and retain their advantage wherever the paths remain disjoint.

cs.NI↗

arXiv2025

Investigating Web Content Delivery Performance over Starlink

Low Earth Orbit (LEO) satellite ISPs promise universal Internet connectivity, yet their interaction with content delivery remains poorly understood. We present the first comprehensive measurement study decomposing Starlink's web content delivery performance decomposed across Point of Presence (PoP), DNS, and CDN layers. Through two years of measurements combining 225K Cloudflare AIM tests, M-Lab data, and active probing from 99 RIPE Atlas and controlled Starlink probes, we collect 6.1M traceroutes and 10.8M DNS queries to quantify how satellite architecture disrupts terrestrial CDN assumptions. We identify three distinct performance regimes based on infrastructure density. Regions with local content-rich PoPs achieve near-terrestrial latencies with the satellite segment dominating 80-90% of RTT. Infrastructure-sparse regions suffer cascading penalties: remote PoPs force distant resolver selection, which triggers CDN mis-localization, pushing latencies beyond 200 ms. Dense-infrastructure regions show minimal sensitivity to PoP changes. Leveraging Starlink's infrastructure expansion in early 2025 as a natural experiment, we demonstrate that relocating PoPs closer to user location reduces median page-fetch times by 60%. Our findings reveal that infrastructure proximity, not satellite coverage, influences web performance, requiring fundamental changes to CDN mapping and DNS resolution for satellite ISPs.

cs.NI↗

arXiv2025

BISCAY: Practical Radio KPI Driven Congestion Control for Mobile Networks

Mobile application performance relies heavily on the congestion control design of the underlying transport, which is typically bottlenecked by cellular link and has to cope with rapid cellular link bandwidth fluctuations. We observe that radio KPI measurements from the mobile device chipset can be exploited for precise and timely measurement of available bandwidth on the cellular link. Building on this insight, we propose Biscay, a practical and radio KPI-driven congestion control system design for mobile networks. Biscay leverages OpenDiag, the in-kernel real-time radio KPI extraction tool we introduce in this paper, along with our KPI-based accurate bandwidth determination layer towards dynamically adjusting the congestion window to optimally use the available bandwidth while keeping delay to the minimum. Our solution is practical and deployable, as shown through our implementation of Biscay and OpenDiag on unrooted Android 5G phones. We extensively evaluate Biscay against different state-of-the-art congestion control designs including BBR and CUBIC with emulations driven by real measurement traces as well as real-world experiments spanning diverse 4G and 5G scenarios, and show that it provides significant average and tail delay improvements (typically over 90% reduction) while yielding better or similar throughput. These gains are enabled by 100% improvement in the granularity of on-device radio KPI measurements with OpenDiag compared to existing alternatives like MobileInsight.

cs.NI↗

arXiv2024

Through the Lens of Google CrUX: Dissecting Web Browsing Experience Across Devices and Countries

User quality of experience in the context of Web browsing is being researched widely, with plenty of developments occurring alongside technological advances, not seldom driven by big industry players. With the huge reach and infrastructure of Google, the Chrome User Experience Report (CrUX) provides quantitative real-life measurement data of a vast magnitude. Analysis of this steadily expanding dataset aggregating different user experience metrics, yields tangible insights into actual trends and developments. Hence, this paper is the first to study the CrUX dataset from the viewpoint of relevant metrics by quantitative evaluation of users Web browsing experience across three device types and nine European countries. Analysis of data segmented by connection type in the device dimension shows desktops outperforming other device types for all metrics. Similar analysis in the country dimension, shows North European countries (Sweden, Finland) having maximum 4G connections (85.99%, 81.41% respectively) and steadily performing 25%-36% better at the 75th percentile across all metrics compared to the worst performing country. Such a high-level longitudinal analysis of real-life Web browsing experience provides an extensive base for future research.

cs.NI↗

arXiv2022

ACP+: An Age Control Protocol for the Internet

We present ACP+, an age control protocol, which is a transport layer protocol that regulates the rate at which update packets from a source are sent over the Internet to a monitor. The source would like to keep the average age of sensed information at the monitor to a minimum, given the network conditions. Extensive experimentation helps us shed light on age control over the current Internet and its implications for sources sending updates over a shared wireless access to monitors in the cloud. We also show that many congestion control algorithms proposed over the years for the Transmission Control Protocol (TCP), including hybrid approaches that achieve higher throughputs at lower delays than traditional loss-based congestion control, are unsuitable for age control.

cs.NI↗

arXiv2022

Perspectives on Negative Research Results in Pervasive Computing

Not all research leads to fruitful results; trying new ways or methods may surpass the state of the art, but sometimes the hypothesis is not proven or the improvement is insignificant. In a systems discipline like pervasive computing, there are many sources of errors, from hardware issues over communication channels to heterogeneous software environments. However, failure to succeed is not a failure to progress. It is essential to create platforms for sharing insights, experiences, and lessons learned when conducting research in pervasive computing so that the same mistakes are not repeated. And sometimes, a problem is a symptom of discovering new research challenges. Based on the collective input of the First International Workshop on Negative Results in Pervasive Computing (PerFail 2022), co-located with the 20th International Conference on Pervasive Computing and Communications (PerCom 2022), this paper presents a comprehensive discussion on perspectives on publishing negative results and lessons learned in pervasive computing.

cs.DC↗

arXiv2022

A Longitudinal View at the Adoption of Multipath TCP

Multipath TCP (MPTCP) extends traditional TCP to enable simultaneous use of multiple connection endpoints at the source and destination. MPTCP has been under active development since its standardization in 2013, and more recently in February 2020, MPTCP was upstreamed to the Linux kernel. In this paper, we provide an in-depth analysis of MPTCPv0 in the Internet and the first analysis of MPTCPv1 to date. We probe the entire IPv4 address space and an IPv6 hitlist to detect MPTCP-enabled systems operational on port 80 and 443. Our scans reveal a steady increase in MPTCPv0-capable IPs, reaching 13k+ on IPv4 (2$\times$ increase in one year) and 1k on IPv6 (40$\times$ increase). MPTCPv1 deployment is comparatively low with $\approx$100 supporting hosts in IPv4 and IPv6, most of which belong to Apple. We also discover a substantial share of seemingly MPTCP-capable hosts, an artifact of middleboxes mirroring TCP options. We conduct targeted HTTP(S) measurements towards select hosts and find that middleboxes can aggressively impact the perceived quality of applications utilizing MPTCP. Finally, we analyze two complementary traffic traces from CAIDA and MAWI to shed light on the real-world usage of MPTCP. We find that while MPTCP usage has increased by a factor of 20 over the past few years, its traffic share is still quite low.

cs.NI↗

arXiv2022

Coexistence of Age Sensitive Traffic and High Throughput Flows: Does Prioritization Help?

We study the coexistence of high throughput traffic flows with status update flows that require timely delivery of updates. A mix of these flows share an end-to-end path that includes a WiFi access network followed by paths over the Internet to a server in the cloud. Using real-world experiments, we show that commonly used methods of prioritization (DSCP at the IP layer and EDCA at the 802.11 MAC layer) in networks are highly effective in isolating status update flows from the impact of high throughput flows in the absence of WiFi access contention, say when all flows originate from the same WiFi client. Prioritization, however, isn't as effective in the presence of contention that results from the throughput and status update flows sharing WiFi. This results in prioritized status update flows suffering from a time-average age of information at the destination server that is about the same as when all flows have the same priority.

cs.NI↗

arXiv2022

Impact of Evolving Protocols and COVID-19 on Internet Traffic Shares

The rapid deployment of new Internet protocols over the last few years and the COVID-19 pandemic more recently (2020) has resulted in a change in the Internet traffic composition. Consequently, an updated microscopic view of traffic shares is needed to understand how the Internet is evolving to capture both such shorter- and longer-term events. Toward this end, we observe traffic composition at a research network in Japan and a Tier-1 ISP in the USA. We analyze the traffic traces passively captured at two inter-domain links: MAWI (Japan) and CAIDA (New York-Sao Paulo), which cover 100GB of data for MAWI traces and 4TB of data for CAIDA traces in total. We begin by studying the impact of COVID-19 on the MAWI link: We find a substantial increase in the traffic volume of OpenVPN and rsync, as well as increases in traffic volume from cloud storage and video conferencing services, which shows that clients shift to remote work during the pandemic. For traffic traces between March 2018 to December 2018, we find that the use of IPv6 is increasing quickly on the CAIDA monitor: The IPv6 traffic volume increases from 1.1% in March 2018 to 6.1% in December 2018, while the IPv6 traffic share remains stable in the MAWI dataset at around 9% of the traffic volume. Among other protocols at the application layer, 60%-70% of IPv4 traffic on the CAIDA link is HTTP(S) traffic, out of which two-thirds are encrypted; for the MAWI link, more than 90% of the traffic is Web, of which nearly 75% is encrypted. Compared to previous studies, this depicts a larger increase in encrypted Web traffic of up to a 3-to-1 ratio of HTTPS to HTTP. As such, our observations in this study further reconfirm that traffic shares change with time and can vary greatly depending on the vantage point studied despite the use of the same generalized methodology and analyses, which can also be applied to other traffic monitoring datasets.

cs.NI↗

arXiv2021

From Single Lane to Highways: Analyzing the Adoption of Multipath TCP in the Internet

Multipath TCP (MPTCP) extends traditional TCP to enable simultaneous use of multiple connection endpoints at the source and destination. MPTCP has been under active development since its standardization in 2013, and more recently in February 2020, MPTCP was upstreamed to the Linux kernel. In this paper, we provide the first broad analysis of MPTCPv0 in the Internet. We probe the entire IPv4 address space and an IPv6 hitlist to detect MPTCP-enabled systems operational on port 80 and 443. Our scans reveal a steady increase in MPTCP-capable IPs, reaching 9k+ on IPv4 and a few dozen on IPv6. We also discover a significant share of seemingly MPTCP-capable hosts, an artifact of middleboxes mirroring TCP options. We conduct targeted HTTP(S) measurements towards select hosts and find that middleboxes can aggressively impact the perceived quality of applications utilizing MPTCP. Finally, we analyze two complementary traffic traces from CAIDA and MAWI to shed light on the real-world usage of MPTCP. We find that while MPTCP usage has increased by a factor of 20 over the past few years, its traffic share is still quite low.

cs.NI↗

arXiv2021

Beyond QUIC v1: A First Look at Recent Transport Layer IETF Standardization Efforts

The transport layer is ossified. With most of the research and deployment efforts in the past decade focussing on the Transmission Control Protocol (TCP) and its extensions, the QUIC standardization by the Internet Engineering Task Force (IETF) is to be finalized in early 2021. In addition to addressing the most urgent issues of TCP, QUIC ensures its future extendibility and is destined to drastically change the transport protocol landscape. In this work, we present a first look at emerging protocols and their IETF standardization efforts beyond QUIC v1. While multiple proposed extensions improve on QUIC itself, Multiplexed Application Substrate over QUIC Encryption (MASQUE) as well as WebTransport present different approaches to address long-standing problems, and their interplay extends on QUIC's take to address transport layer ossification challenges.

cs.NI↗

arXiv2021

An Empirical Study of Ageing in the Cloud

We quantify, over inter-continental paths, the ageing of TCP packets, throughput and delay for different TCP congestion control algorithms containing a mix of loss-based, delay-based and hybrid congestion control algorithms. In comparing these TCP variants to ACP+, an improvement over ACP, we shed better light on the ability of ACP+ to deliver timely updates over fat pipes and long paths. ACP+ estimates the network conditions on the end-to-end path and adapts the rate of status updates to minimize age. It achieves similar average age as the best (age wise) performing TCP algorithm but at end-to-end throughputs that are two orders of magnitude smaller. We also quantify the significant improvements that ACP+ brings to age control over a shared multiaccess channel.

cs.NI↗

arXiv2019

Is two greater than one?: Analyzing Multipath TCP over Dual-LTE in the Wild

Multipath TCP (MPTCP) is a standardized TCP extension which allows end-hosts to simultaneously exploit all of their network interfaces. The recent proliferation of dual-SIM mobile phones makes multi-LTE MPTCP setup an attractive option. We perform extensive measurements of MPTCP over two LTE connections in low and high-speed mobility scenarios over five months, both in controlled and in-the-wild environments. Our findings indicate that MPTCP performance decreases at high speeds due to increased frequency of signal strength drops and handovers. Both LTE paths experience frequent changes which result in a sub-optimal subflow utilization. We also find that while path changes are unpredictable, their impact on MPTCP follows a deterministic trend. Finally, we show that both application traffic patterns and congestion control variants impact MPTCP adaptability at high speeds.

cs.NI↗

arXiv2019

ACP: An End-to-End Transport Protocol for Delivering Fresh Updates in the Internet-of-Things

The next generation of networks must support billions of connected devices in the Internet-of-Things (IoT). To support IoT applications, sources sense and send their measurement updates over the Internet to a monitor (control station) for real-time monitoring and actuation. Ideally, these updates would be delivered at a high rate, only constrained by the sensing rate supported by the sources. However, given network constraints, such a rate may lead to delays in delivery of updates at the monitor that make the freshest update at the monitor unacceptably old for the application. We propose a novel transport layer protocol, namely the Age Control Protocol (ACP), that enables timely delivery of such updates to monitors, in a network-transparent manner. ACP allows the source to adapt its rate of updates to dynamic network conditions such that the average age of the sensed information at the monitor is minimized. We detail the protocol and the proposed control algorithm. We demonstrate its efficacy using extensive simulations and real-world experiments, which have a source send its updates over the Internet to a monitor on another continent.

cs.NI↗

arXiv2018

QAware: A Cross-Layer Approach to MPTCP Scheduling

Multipath TCP (MPTCP) allows applications to transparently use all available network interfaces by creating a TCP subflow per interface. One critical component of MPTCP is the scheduler that decides which subflow to use for each packet. Existing schedulers typically use estimates of end-to-end path properties, such as delay and bandwidth, for making the scheduling decisions. In this paper, we show that these scheduling decisions can be significantly improved by incorporating readily available local information from the device driver queues in the decision-making process. We propose QAware, a novel cross-layer approach for MPTCP scheduling. QAware combines end-to-end delay estimates with local queue buffer occupancy information and allows for a better and faster adaptation to the network conditions. This results in more efficient use of the available resources and considerable gains in aggregate throughput. We present the design of QAware and evaluate its performance through simulations, and also through real experiments, comparing it to existing schedulers. Our results show that QAware performs significantly better than other available approaches for various use-cases and applications.

cs.NI↗

arXiv2017

More Than The Sum Of Its Parts: Exploiting Cross-Layer and Joint-Flow Information in MPTCP

Multipath TCP (MPTCP) is an extension to TCP which aggregates multiple parallel connections over available network interfaces. MPTCP bases its scheduling decisions on the individual RTT values observed at the subflows, but does not attempt to perform any kind of joint optimization over the subflows. Using the MPTCP scheduler as an example, in this paper we demonstrate that exploiting cross-layer information and optimizing scheduling decisions jointly over the multiple flows, can lead to significant performance gains. While our results only represent a single data point, they illustrate the need to look at MPTCP from a more holistic point of view and not treat the connections separately, as is currently being done. We call for new approaches and research into how multiple parallel connections offered by MPTCP should be used in an efficient and fair manner.

cs.NI↗