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Department of Computer Science and Technology

Date: 
Thursday, 21 May, 2026 - 15:00 to 16:00
Speaker: 
Sawsan El Zahr, University of Oxford
Venue: 
FW11

Abstract:

As sustainability becomes a requirement in network operations, accurately quantifying the carbon footprint of Internet traffic is essential. While energy-aware networking has seen significant attention, the ability to trace carbon emissions at the flow level remains an open challenge due to the complexity of shared infrastructure and lack of related telemetry. In this paper, we present a methodology to obtain fine-grained per-flow carbon emissions from traffic statistics. To this end, we collect power measurements from three switches under varying traffic conditions, including synthetic and real-world traces. From these measurements, we derive a regression model that accurately estimates instantaneous router power consumption using only throughput and packet rate counters–achieving >96% accuracy across all switch types and traces. We then extend this model to compute per-flow carbon emissions, distinguishing between consequential and attributional perspectives, and validate the results using traces from CAIDA and Google services. Our findings uncover actionable insights into how flow and network characteristics such as packet size, packet rate, and network utilization influence carbon cost. Finally, we propose feasible deployment strategies for flow-level carbon estimation frameworks. This work provides a foundational step towards enabling carbon-aware flow-level decision-making for users, applications, and network operators.

Speaker bio:

Sawsan El Zahr is a final year PhD student within the Computing Infrastructure Group at the University of Oxford. She received her B.E. in Electrical Engineering and M.S. in Computer and Communications Engineering from the Lebanese American University in 2021 and 2022, respectively. Her current research focuses on reducing the carbon footprint of computer networks. Her focus is on carbon emissions, rather than energy consumption alone, and her research combines routing algorithms, power modelling, and net-zero solutions. Sawsan is a recipient of the Oxford-Qatar-Thatcher scholarship and a titular Clarendon scholarship. Her research has earned her several awards, including the Dyson Award for Outstanding Research towards a more sustainable future at STEM for Britain 2024 and the 2024 Applied Networking Research Prize (ANRP) issued by IRTF.

Online meeting link:

Microsoft Teams

Seminar series: 
Systems Research Group Seminar

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