33 Axiomatizing Congestion Control DORON ZARCHY, Hebrew University of Jerusalem RADHIKA MITTAL, University of Illinois at Urbana-Champaign MICHAEL SCHAPIRA, Hebrew University of Jerusalem SCOTT SHENKER, UC Berkeley, ICSI The overwhelmingly large design space of congestion control protocols, along with the increasingly diverse range of application environments, makes evaluating such protocols a daunting task. Simulation and experi- ments are very helpful in evaluating the performance of designs in specific contexts, but give limited insight into the more general properties of these schemes and provide no information about the inherent limits of congestion control designs (such as, which properties are simultaneously achievable and which are mutually exclusive). In contrast, traditional theoretical approaches are typically focused on the design of protocols that achieve to specific, predetermined objectives (e.g., network utility maximization), or the analysis of specific protocols (e.g., from control-theoretic perspectives), as opposed to the inherent tensions/derivations between desired properties. To complement today’s prevalent experimental and theoretical approaches, we put forth a novel principled framework for reasoning about congestion control protocols, which is inspired by the axiomatic approach from social choice theory and game theory. We consider several natural requirements (“axioms”) from congestion control protocols – e.g., efficient resource-utilization, loss-avoidance, fairness, stability, and TCP-friendliness – and investigate which combinations of these can be achieved within a single design. Thus, our framework allows us to investigate the fundamental tradeoffs between desiderata, and to identify where existing and new congestion control architectures fit within the space of possible outcomes. CCS Concepts: • Networks → Network protocols; ACM Reference Format: Doron Zarchy, Radhika Mittal, Michael Schapira, and Scott Shenker. 2019. Axiomatizing Congestion Control. Proc. ACM Meas. Anal. Comput. Syst. 3, 2, Article 33 (June 2019), 33 pages. https://doi.org/10.1145/3326148 1 Introduction Recent years have witnessed a revival of both industrial and academic interest in improving congestion control designs. The quest for better congestion control is complicated by the extreme diversity and range of (i) the design space (as exemplified by the stark conceptual and operational differences between recent proposals [8, 14, 18, 19, 49, 50]), (ii) the desired properties (ranging from high performance to fairness to TCP-friendliness), (iii) the envisioned operational setting (inter- and intra-datacenter, wireless, the commercial Internet, satellite), and (iv) the application loads and requirements (small vs. large traffic demands, latency- vs. bandwidth-sensitive). Most congestion control research uses simulation and experiments under a limited range of network conditions. This is extremely important for understanding the detailed performance of Authors’ addresses: Doron Zarchy, Hebrew University of Jerusalem, doronz@cs.huji.ac.il; Radhika Mittal, University of Illinois at Urbana-Champaign, radhikam@illinois.edu; Michael Schapira, Hebrew University of Jerusalem, schapiram@huji. ac.il; Scott Shenker, UC Berkeley, ICSI, shenker@icsi.berkeley.edu. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from permissions@acm.org. © 2019 Association for Computing Machinery. 2476-1249/2019/6-ART33 $15.00 https://doi.org/10.1145/3326148 Proc. ACM Meas. Anal. Comput. Syst., Vol. 3, No. 2, Article 33. Publication date: June 2019.