DEGREE PROJECT IN INFORMATION AND COMMUNICATION TECHNOLOGY, SECOND CYCLE, 30 CREDITS STOCKHOLM, SWEDEN 2020 Is QUIC a Better Choice than TCP in the 5G Core Network Service Based Architecture? PETHRUS GÄRDBORN KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE Is QUIC a Better Choice than TCP in the 5G Core Network Service Based Architecture? PETHRUS GÄRDBORN Master in Communication Systems Date: November 22, 2020 Supervisor at KTH: Marco Chiesa Supervisor at Ericsson: Zaheduzzaman Sarker Examiner: Peter Sjödin School of Electrical Engineering and Computer Science Host company: Ericsson AB Swedish title: Är QUIC ett bättre val än TCP i 5G Core Network Service Based Architecture? iii Abstract The development of the 5G Cellular Network required a new 5G Core Network and has put higher requirements on its protocol stack. For decades, TCP has been the transport protocol of choice on the Internet. In recent years, major Internet players such as Google, Facebook and CloudFlare have opted to use the new QUIC transport protocol. The design assumptions of the Internet (best-effort delivery) differs from those of the Core Network. The aim of this study is to investigate whether QUIC’s benefits on the Internet will translate to the 5G Core Network Service Based Architecture. A testbed was set up to emulate traffic patterns between Network Functions. The results show that QUIC reduces average request latency to half of that of TCP, for a majority of cases, and doubles the throughput even under optimal network conditions with no packet loss and low (20 ms) RTT. Additionally, by measuring request start and end times “on the wire”, without taking into account QUIC’s shorter connection establishment, we believe the results indicate QUIC’s suitability also under the long-lived (standing) connection model. In conclusion, from a performance perspective, QUIC appears to be a better candidate than TCP in the 5G Core Network Service Based Architecture. iv Sammanfattning Den snabba utvecklingen av det mobila nätverket 5G har medfört högre krav för 5G Core Network och dess protokoll. Under årtionden har TCP dominerat Internet som transportprotokoll. De senaste åren har dock stora aktörer som Google, Facebook och CloudFlare börjat använda det relativt nya transport- protokollet QUIC. Designantagandena för Internet (best-effort delivery) och 5G Core skiljer sig dock åt. Målet med denna studie är att undersöka huruvida QUIC är lika fördelaktigt att använda i 5G Core Network Service Based Ar- chitecture som på Internet. En testbädd sattes up för att emulera trafiken mel- lan två nätverksfunktioner. Resultaten visar att QUIC har halverar latensen jämfört med TCP i en majoritet av fallen, samt dubblerar genomströmning- en även under mycket goda nätverksförhållanden där inga paket förloras och tur-och-retur-tiden är låg (20 ms). Genom att mäta ett HTTP requests start- och sluttider “rakt på ledningen”, utan att inbegripa QUICs kortare förbin- delseetableringstid, menar vi att resultaten indikerar QUICs lämplighet också vid användande av långlivade kommunikationsförbindelser. Med avseende på prestanda, framstår QUIC som ett bättre alternativ än TCP också i 5G Core Network Service Based Architecture. v Acknowledgements I would like to express my gratitude to several experts at Ericsson for the op- portunity to work on this interesting topic and for the enriching discussions that emerged. I would like to thank my industrial supervisor, Zaheduzzaman Sarker, for his knowledgeable guidance, help, and feedback during this project. I would like to thank Patrick Sellstedt, for providing me the platform at Eric- sson for this work. I would also like to thank Magnus Westerlund and Mirja Kühlewind for additional very valuable feedback and insights. I am also grateful to my KTH supervisor, Marco Chiesa, for his valuable feedback and insights, and to my examiner, Peter Sjödin, for reviewing and approving the initial thesis proposal and providing helpful academic feedback on the report. I would also like to thank my parents for always being supportive, my father for the encouragement and support during all my studies, and my mother for believing in a positive outcome of this work. Finally, I want to thank my wife for enabling me to spend time, sometimes on nights and weekends, to track down bugs and finalize the report. Without your support, I would not be able to have both a Master Thesis and a beautiful family as well. Contents 1 Introduction 1 1.1 Overview . .1 1.2 QUIC vs. TCP . .2 1.3 Problem Area . .3 1.4 Goals . .4 1.5 Methodology . .4 1.6 Delimitations . .5 1.7 Ethics and Sustainability . .5 1.8 Outline . .5 2 Background 7 2.1 Mobile Systems Architecture . .7 2.1.1 Common Logical Building Blocks . .7 2.1.2 5G Core Service Based Architecture . .8 2.2 Protocols . .9 2.2.1 Introduction . .9 2.2.2 TCP/TLS . 11 2.2.3 HTTP/1.1 and HTTP/2 . 12 2.2.4 QUIC and HTTP/3 . 13 2.3 QUIC on the Web vs. the 5G Core . 15 2.4 Related Work . 16 2.4.1 QUIC in the 5G Core Service Based Architecture . 16 2.4.2 QUIC on the Web . 17 3 Method 19 3.1 Testbed Requirements . 19 3.1.1 Overview . 19 3.1.2 Requirements to Ensure Comparability . 20 3.2 Testbed Components . 24 vi CONTENTS vii 3.2.1 Platform & Network Tools . 24 3.2.2 QUIC/TCP Client & Server Implementations . 25 3.3 Benchmark Parameter Settings . 26 3.3.1 Main Parameters . 26 3.3.2 Sub-parameters . 27 3.4 Key Performance Indicators . 27 3.5 Test Design . 28 4 Results 30 4.1 Sub-parameters . 30 4.1.1 Number of Multiplexed Requests . 31 4.1.2 Request Payload . 35 4.1.3 Response Payload . 39 4.2 Main Parameters . 46 4.2.1 Round Trip Time . 46 4.2.2 Packet Loss Rate . 47 5 Discussion 50 5.1 Faster Connection Establishment – Not the Only Factor for Improving Latency . 50 5.2 QUIC has a Significant Advantage Also in QoS Networks . 52 5.3 Performance Difference is Negligible With Few Multiplexed GET Requests . 52 5.4 Impacts of the Method used to Measure Request Duration . 53 5.5 Limitations & Future Work . 53 5.6 Conclusions . 54 Bibliography 56 Chapter 1 Introduction A short background overview of the research is presented followed by a brief comparison of QUIC and TCP. We then lay out the problem area, research question and hypotheses followed by the goals, methodology and a brief dis- cussion of ethical concerns and impacts on sustainability. Chapter 2 contains a more thorough background presentation. 1.1 Overview Mobile telecommunication systems evolve continuously in order to meet new and increasing demands such as massive IoT deployment, time-sensitive re- mote control of robots over a network and increased throughput. Between 2010 and 2020, there was an expected capacity increase of a 1000 times more devices, 100 times higher data rate and 10 times lower latency. The fifth gener- ation (5G) mobile telecommunication system has been designed to meet these demands. [1] 3G, 4G and 5G architectures all have in common that they consist of two networks: the Radio Access Network and the Core Network. The role of the Radio Access Network is to provide a connection between the User Equipment – a cell phone or other device – and the Core Network. The Core Network is responsible for handling everything related to connection management and the forwarding of data to and from the Internet. It is logically divided in two parts, the Control Plane and the User Plane. The User Plane only handles the forwarding of data and the Control Plane handles all other functionality such as authentication, authorization, policy control and so forth. [2] In order to modularize network components and make them independently scalable and evolvable, the new Service Based Architecture (SBA) was in- 1 2 CHAPTER 1. INTRODUCTION troduced with 5G for the Control Plane of the Core Network [3]. SBA is a microservices-type architecture where the goals are to provide easier scaling and more rapid development [4, p. 12]. According to the "System architecture for the 5G System" specification [3], Network Functions (NFs) communicate over Representational State Transfer (REST) interfaces via request-response and subscribe-notify communication patterns. The authors argue that by iso- lating NFs and using generic protocols such as HTTP for communication, scal- ing and evolvability of individual components become easier; thereby, SBA also paves the way for eventual transitioning into a cloud-based environment where NFs run in containers in data centers. The choice of protocols impacts all types of communication. With the introduction of REST interfaces in SBA, the protocol stack of the higher layers – layer 3 to layer 5 – becomes very similar to the protocol stack used on the Web [4, p. 22]. Therefore, any new protocol development in the Web stack could also be of use in the SBA protocol stack. In this thesis, we are interested in evaluating the transport protocol performance within the context of the 5G Core Network Control Plane SBA. 1.2 QUIC vs. TCP The Transmission Control Protocol (TCP) has been the transport protocol of choice on the Internet for decades and provides reliability as well as congestion control [5]. In conjunction with the Transport Layer Security (TLS) protocol, authentication and encryption are also ensured [6]. However, in 2012 Google laid out the guidelines for a new transport protocol called QUIC [7]. The protocol was submitted to the Internet Engineering Task Force (IETF) which has since continued the development [8] and made substantial changes to the protocol. It is the IETF draft of QUIC [9] that this thesis is concerned with. To understand why companies such as Google, CloudFlare and others opt for QUIC whenever possible [10, 11], we need to understand the design goals of QUIC and in what regards QUIC performs better than TCP.