DOCSLIB.ORG

Juha Vihervaara Dual-Mode Congestion Control Mechanism for Video Services

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Juha Vihervaara Dual-Mode Congestion Control Mechanism for Video Services Juha Vihervaara Dual-Mode Congestion Control Mechanism for Video Services Julkaisu 1541 • Publication 1541 Tampere 2018 Tampereen teknillinen yliopisto. Julkaisu 1541 Tampere University of Technology. Publication 1541 Juha Vihervaara Dual-Mode Congestion Control Mechanism for Video Services Thesis for the degree of Doctor of Science in Technology to be presented with due permission for public examination and criticism in Auditorium 125, at Tampere University of Technology - Pori, on the 11th of May 2018, at 12 noon. Tampereen teknillinen yliopisto - Tampere University of Technology Tampere 2018 Doctoral candidate: Juha Vihervaara Laboratory of Electronics and Communications Engineering Faculty of Computing and Electrical Engineering Tampere University of Technology Finland Supervisor: Tarmo Lipping, professor Laboratory of Signal Processing Faculty of Computing and Electrical Engineering Tampere University of Technology Finland Pre-examiners: Marilia Curado, assistant professor Department of Informatics Engineering University of Coimbra Portugal Pasi Sarolahti, university lecturer Department of Communications and Networking Aalto University Finland Opponent: Ismo Hakala, professor Information Technology Kokkola University Consortium Chydenius Finland ISBN 978-952-15-4124-7 (printed) ISBN 978-952-15-4128-5 (PDF) ISSN 1459-2045 Juha Vihervaara, 2018. “Dual-Mode Congestion Control Mechanism for Video Services”. Tampere University of Technology, Tampere, Finland. Keywords: Congestion control, Video service Abstract Recent studies have shown that video services represent over half of Internet traffic, with a growing trend. Therefore, video traffic plays a major role in network congestion. Currently on the Internet, congestion control is mainly implemented through overprovisioning and TCP congestion control. Although some video services use TCP to implement their transport services in a manner that actually works, TCP is not an ideal protocol for use by all video applications. For example, UDP is often considered to be more suitable for use by real-time video applications. Unfortunately, UDP does not implement congestion control. Therefore, these UDP-based video services operate without any kind of congestion control support unless congestion control is implemented on the application layer. There are also arguments against massive overprovisioning. Due to these factors, there is still a need to equip video services with proper congestion control. Most of the congestion control mechanisms developed for the use of video services can only offer either low priority or TCP-friendly real-time services. There is no single congestion control mechanism currently that is suitable and can be widely used for all kinds of video services. This thesis provides a study in which a new dual-mode congestion control mechanism is proposed. This mechanism can offer congestion control services for both service types. The mechanism includes two modes, a backward-loading mode and a real-time mode. The backward-loading mode works like a low-priority service where the bandwidth is given away to other connections once the load level of a network is high enough. In contrast, the real-time mode always demands its fair share of the bandwidth. The behavior of the new mechanism and its friendliness toward itself, and the TCP protocol, have been investigated by means of simulations and real network tests. It was found that this kind of congestion control approach could be suitable for video services. The new mechanism worked acceptably. In particular, the mechanism behaved toward itself in a very friendly way in most cases. The averaged TCP fairness was at a good level. In the worst cases, the faster connections received about 1.6 times as much bandwidth as the slower connections. i Preface This thesis contains the results of research work, which has been carried out at the Pori Campus of the Tampere University of Technology. This work has been a challenging journey, including both uphill and downhill phases. Fortunately, I was not alone on this road but accompanied by a group of people always willing to coach, support, help, and motivate me. Certainly, I would have never reached the endpoint of this trip without the help and support of others. For this reason, I would like to thank all the people who have been involved in the process of creating this thesis throughout the years. First, I would like to thank my supervisors, Professors Pekka Loula and Tarmo Lipping, for taking me on as their student and guiding me through this study. They have been the ideal advisors in every respect. Secondly, I would like to thank my colleagues and fellow students for their support. I would also like to thank the pre-examiners Marilia Curado and Pasi Sarolahti for their constructive comments and criticism, which have been invaluable for the completion of this thesis. This work has been supported financially by the Ulla Tuominen Foundation, the High Technology Foundation of Satakunta, and the Finnish Cultural Foundation. I wish to express my thanks to these foundations. I owe a special debt of gratitude to my parents and family. They, more than anyone else, have been the reason I have been able to get this far. iii Table of Contents Abbreviations .................................................................................................................. ix 1 Introduction ................................................................................................................... 1 1.1. Background ....................................................................................................... 1 1.2. Problem statement and the aims of the thesis ................................................... 6 1.3. Structure of the thesis ....................................................................................... 7 2 Review of Congestion Control ................................................................................. 9 2.1. Background of congestion control .................................................................... 9 2.2. Queue management ........................................................................................ 13 2.2.1. Traffic phase effects and active queue management ......................... 15 2.2.2. Random Early Detection ................................................................... 16 2.2.3. CoDel ................................................................................................ 18 2.3. Fairness ........................................................................................................... 19 2.4. Round-trip times ............................................................................................. 21 2.5. AIMD principle .............................................................................................. 22 2.6. Stability, scalability, and selfish users ............................................................ 25 2.7. Implicit and explicit congestion control ......................................................... 27 2.7.1. Implicit Congestion Control .............................................................. 28 2.7.2. Explicit Congestion Control .............................................................. 28 2.8. Window-based versus rate-based congestion control ..................................... 30 2.9. Overprovisioning ............................................................................................ 31 2.10. Challenging environments ........................................................................ 32 3 TCP/IP Congestion Control and Video Transfer .................................................... 37 3.1. TCP congestion control .................................................................................. 37 3.1.1. TCP timeout management ................................................................. 38 3.1.2. Increasing sending rate by using slow start and congestion avoidance algorithms ....................................................................................................... 39 3.1.3. Decreasing sending rate by using slow start, fast retransmit, and fast recovery algorithms ........................................................................................ 42 3.1.4. TCP versions ..................................................................................... 44 3.1.5. TCP fairness ...................................................................................... 46 3.1.6. Explicit Congestion Notification ....................................................... 47 3.2. Delay-based congestion control mechanisms ................................................. 49 3.2.1. Packet Pair ......................................................................................... 49 3.2.2. TCP Vegas......................................................................................... 50 3.2.3. TCP-LP.............................................................................................. 53 3.2.4. Low Extra Delay Background Transport .......................................... 54 3.2.5. Delay Gradient Congestion Control Algorithm ................................ 55 3.3. Congestion control for multimedia streaming ................................................ 57 3.3.1. TCP for real-time multimedia applications ....................................... 57 3.3.2. Rate Adaptation Protocol .................................................................. 58 v 3.3.3. Enhanced loss-delay based adaptation algorithm.............................
Load more

Recommended publications
  • Modeling and Performance Evaluation of LTE Networks with Different TCP Variants Ghassan A
    World Academy of Science, Engineering and Technology International Journal of Electronics and Communication Engineering Vol:5, No:3, 2011 Modeling and Performance Evaluation of LTE Networks with Different TCP Variants Ghassan A. Abed, Mahamod Ismail, and Kasmiran Jumari Abstract—Long Term Evolution (LTE) is a 4G wireless Comparing the performance of 3G and its evolution to LTE, broadband technology developed by the Third Generation LTE does not offer anything unique to improve spectral Partnership Project (3GPP) release 8, and it's represent the efficiency, i.e. bps/Hz. LTE improves system performance by competitiveness of Universal Mobile Telecommunications System using wider bandwidths if the spectrum is available [2]. (UMTS) for the next 10 years and beyond. The concepts for LTE systems have been introduced in 3GPP release 8, with objective of Universal Terrestrial Radio Access Network Long-Term high-data-rate, low-latency and packet-optimized radio access Evolution (UTRAN LTE), also known as Evolved UTRAN technology. In this paper, performance of different TCP variants (EUTRAN) is a new radio access technology proposed by the during LTE network investigated. The performance of TCP over 3GPP to provide a very smooth migration towards fourth LTE is affected mostly by the links of the wired network and total generation (4G) network [3]. EUTRAN is a system currently bandwidth available at the serving base station. This paper describes under development within 3GPP. LTE systems is under an NS-2 based simulation analysis of TCP-Vegas, TCP-Tahoe, TCP- Reno, TCP-Newreno, TCP-SACK, and TCP-FACK, with full developments now, and the TCP protocol is the most widely modeling of all traffics of LTE system.
    [Show full text]
  • Analysing TCP Performance When Link Experiencing Packet Loss
    Analysing TCP performance when link experiencing packet loss Master of Science Thesis [in the Programme Networks and Distributed System] SHAHRIN CHOWDHURY KANIZ FATEMA Chalmers University of Technology University of Gothenburg Department of Computer Science and Engineering Göteborg, Sweden, October 2013 The Author grants to Chalmers University of Technology and University of Gothenburg the non-exclusive right to publish the Work electronically and in a non-commercial purpose make it accessible on the Internet. The Author warrants that he/she is the author to the Work, and warrants that the Work does not contain text, pictures or other material that violates copyright law. The Author shall, when transferring the rights of the Work to a third party (for example a publisher or a company), acknowledge the third party about this agreement. If the Author has signed a copyright agreement with a third party regarding the Work, the Author warrants hereby that he/she has obtained any necessary permission from this third party to let Chalmers University of Technology and University of Gothenburg store the Work electronically and make it accessible on the Internet. Analysing TCP performance when link experiencing packet loss SHAHRIN CHOWDHURY, KANIZ FATEMA © SHAHRIN CHOWDHURY, October 2013. © KANIZ FATEMA, October 2013. Examiner: TOMAS OLOVSSON Chalmers University of Technology University of Gothenburg Department of Computer Science and Engineering SE-412 96 Göteborg Sweden Telephone + 46 (0)31-772 1000 Department of Computer Science and Engineering Göteborg, Sweden October 2013 Acknowledgement We are grateful to our supervisor and examiner Tomas Olovsson for his valuable time and assistance in compilation for this thesis.
    [Show full text]
  • Latency and Throughput Optimization in Modern Networks: a Comprehensive Survey Amir Mirzaeinnia, Mehdi Mirzaeinia, and Abdelmounaam Rezgui
    READY TO SUBMIT TO IEEE COMMUNICATIONS SURVEYS & TUTORIALS JOURNAL 1 Latency and Throughput Optimization in Modern Networks: A Comprehensive Survey Amir Mirzaeinnia, Mehdi Mirzaeinia, and Abdelmounaam Rezgui Abstract—Modern applications are highly sensitive to com- On one hand every user likes to send and receive their munication delays and throughput. This paper surveys major data as quickly as possible. On the other hand the network attempts on reducing latency and increasing the throughput. infrastructure that connects users has limited capacities and These methods are surveyed on different networks and surrond- ings such as wired networks, wireless networks, application layer these are usually shared among users. There are some tech- transport control, Remote Direct Memory Access, and machine nologies that dedicate their resources to some users but they learning based transport control, are not very much commonly used. The reason is that although Index Terms—Rate and Congestion Control , Internet, Data dedicated resources are more secure they are more expensive Center, 5G, Cellular Networks, Remote Direct Memory Access, to implement. Sharing a physical channel among multiple Named Data Network, Machine Learning transmitters needs a technique to control their rate in proper time. The very first congestion network collapse was observed and reported by Van Jacobson in 1986. This caused about a I. INTRODUCTION thousand time rate reduction from 32kbps to 40bps [3] which Recent applications such as Virtual Reality (VR), au- is about a thousand times rate reduction. Since then very tonomous cars or aerial vehicles, and telehealth need high different variations of the Transport Control Protocol (TCP) throughput and low latency communication.
    [Show full text]
  • Lab 6: Understanding Traditional TCP Congestion Control (HTCP, Cubic, Reno)
    NETWORK TOOLS AND PROTOCOLS Lab 6: Understanding Traditional TCP Congestion Control (HTCP, Cubic, Reno) Document Version: 06-14-2019 Award 1829698 “CyberTraining CIP: Cyberinfrastructure Expertise on High-throughput Networks for Big Science Data Transfers” Lab 6: Understanding Traditional TCP Congestion Control Contents Overview ............................................................................................................................. 3 Objectives............................................................................................................................ 3 Lab settings ......................................................................................................................... 3 Lab roadmap ....................................................................................................................... 3 1 Introduction to TCP ..................................................................................................... 3 1.1 TCP review ............................................................................................................ 4 1.2 TCP throughput .................................................................................................... 4 1.3 TCP packet loss event ........................................................................................... 5 1.4 Impact of packet loss in high-latency networks ................................................... 6 2 Lab topology...............................................................................................................
    [Show full text]
  • The Effects of Different Congestion Control Algorithms Over Multipath Fast Ethernet Ipv4/Ipv6 Environments
    Proceedings of the 11th International Conference on Applied Informatics Eger, Hungary, January 29–31, 2020, published at http://ceur-ws.org The Effects of Different Congestion Control Algorithms over Multipath Fast Ethernet IPv4/IPv6 Environments Szabolcs Szilágyi, Imre Bordán Faculty of Informatics, University of Debrecen, Hungary [email protected] [email protected] Abstract The TCP has been in use since the seventies and has later become the predominant protocol of the internet for reliable data transfer. Numerous TCP versions has seen the light of day (e.g. TCP Cubic, Highspeed, Illinois, Reno, Scalable, Vegas, Veno, etc.), which in effect differ from each other in the algorithms used for detecting network congestion. On the other hand, the development of multipath communication tech- nologies is one today’s relevant research fields. What better proof of this, than that of the MPTCP (Multipath TCP) being integrated into multiple operating systems shortly after its standardization. The MPTCP proves to be very effective for multipath TCP-based data transfer; however, its main drawback is the lack of support for multipath com- munication over UDP, which can be important when forwarding multimedia traffic. The MPT-GRE software developed at the Faculty of Informatics, University of Debrecen, supports operation over both transfer protocols. In this paper, we examine the effects of different TCP congestion control mechanisms on the MPTCP and the MPT-GRE multipath communication technologies. Keywords: congestion control, multipath communication, MPTCP, MPT- GRE, transport protocols. 1. Introduction In 1974, the TCP was defined in RFC 675 under the Transmission Control Pro- gram name. Later, the Transmission Control Program was split into two modular Copyright © 2020 for this paper by its authors.
    [Show full text]
  • Computer Networks ICS
    Computer Networks ICS 651 ● congestion collapse ● congestion control: TCP Reno ● congestion control: TCP Vegas ● other ways of detecting congestion ● addressing congestion ● router intervention ● Internet Explicit Congestion Notification ● FIFO queueing ● fair queueing Router Congestion • assume a fast router • two gigabit-ethernet links receiving lots of outgoing data • one (relatively) slow internet link (10 Mb/s uplink speed) sending the outgoing data • if the two links send more than a combined 10 Mb/s over an extended period, the router buffers will fill up • eventually the router will have to discard data due to congestion: more data being sent than the line can carry Congestion Collapse • assume a fixed timeout • if I have n bytes/second to send, I send them • if they get dropped, I retransmit them (total 2n bytes/second, 3n bytes/second, ...) • when there is congestion, packets get dropped • if everybody retransmits with fixed timeout, the amount of data sent grows, increasing congestion • so some congestion (enough to drop packets) causes more congestion!!!! • eventually, very little data gets through, most is discarded • the network is (nearly) down TCP Reno • exponential backoff: if retransmit timer was t before retransmission, it becomes 2t after retransmission • careful RTT measurements give retransmission as soon as possible, but no sooner • keep a congestion window: • effective window is lesser of: (1) flow control window, and (2) congestion window • congestion window is kept only on the sender, and never communicated between
    [Show full text]
  • Better Throughput in TCP Congestion Control Algorithms on Manets
    (IJACSA) International Journal of Advanced Computer Science and Applications, Special Issue on Wireless & Mobile Networks Scalable TCP: Better Throughput in TCP Congestion Control Algorithms on MANETs M.Jehan Dr. G.Radhamani Associate Professor, Department of Computer Science, Professor & Director, Department of Computer Science, D.J.Academy for Managerial Excellence, Dr.G.R.Damodaran College of Science, Coimbatore, India Coimbatore, India Abstract—In the modern mobile communication world the This paper is entirely devoted to evaluating the Control congestion control algorithms role is vital to data transmission Window (cwnd), Round Trip Delay Time (rtt) and Throughput between mobile devices. It provides better and reliable using the TCP BIC, Vegas and Scalable TCP congestion communication capabilities in all kinds of networking control algorithms in the wireless networks. environment. The wireless networking technology and the new kind of requirements in communication systems needs some II. BACKGROUND WORK extensions to the original design of TCP for on coming technology development. This work aims to analyze some TCP congestion A. Congestion Control in Transmission Control Protocol control algorithms and their performance on Mobile Ad-hoc Algorithms Networks (MANET). More specifically, we describe performance TCP (Transmission Control Protocol) is a set of rules behavior of BIC, Vegas and Scalable TCP congestion control (protocol) used along with the Internet Protocol (IP) to send algorithms. The evaluation is simulated through Network data in the form of message units between computers over the Simulator (NS2) and the performance of these algorithms is Internet. It operates at a higher level, concerned only with the analyzed in the term of efficient data transmission in wireless and two end systems.
    [Show full text]
  • An Efficient Mechanism of TCP-Vegas on Mobile IP Networks
    An Efficient Mechanism of TCP-Vegas on Mobile IP Networks Cheng-Yuan Ho, Yi-Cheng Chan, and Yaw-Chung Chen Department of Computer Science and Information Engineering National Chiao Tung University 1001 Ta Hsueh Road, Hsinchu 30050, Taiwan, R.O.C. [email protected], [email protected], [email protected] Abstract— Mobile IP network provides hosts the connectivity Mobile IP [2], [3]. to the Internet while changing locations. However, when using MIP (Mobile Internet Protocol) provides hosts with the TCP Vegas over a mobile network, it may respond to a handoff ability to change their point of attachment to the network by invoking a congestion control algorithm, thereby resulting in performance degradation, because TCP Vegas is sensitive to the without compromising their ability in communications. The change of RTT (Round-Trip Time) and it may recognize the mobility support provided by MIP is transparent to other increased RTT as a result of network congestion. Since TCP protocol layers so as not to affect those applications which do Vegas could not differentiate whether the increased RTT is due not have mobility features. MIP introduces three new entities to route change or network congestion. This work investigates required to support the protocol: the Home Agent (HA), the how to improve the performance of Vegas after a Mobile IP handoff and proposes a variation of TCP Vegas, so-called Demo- Foreign Agent (FA) and the Mobile Node (MN). Further Vegas, which is able to detect the movement of two end-hosts of information on MIP functionality can be found in [2], [3].
    [Show full text]
  • Performance Evaluation of TCP Vegas Over TCP Reno and TCP New Reno Over TCP Reno
    VOL 3 (2019) NO 3 e-ISSN : 2549-9904 ISSN : 2549-9610 INTERNATIONAL JOURNAL ON INFORMATICS VISUALIZATION Performance Evaluation of TCP Vegas over TCP Reno and TCP New Reno over TCP Reno Tanjia Chowdhury #, Mohammad Jahangir Alam # # Department of Computer Science and IT, Southern University Bangladesh, Bangladesh E-mail: [email protected], [email protected] Abstract — In the Transport layer, there are two types of Internet Protocol are worked, namely- Transmission Control Protocol (TCP) and User datagram protocol (UDP). TCP provides connection-oriented service and it can handle congestion control, flow control, and error detection whereas UDP does not provide any of service. TCP has several congestion control mechanisms such as TCP Reno, TCP Vegas, TCP New Reno, TCP Tahoe, etc. In this paper, we have focused on the behavior performance between TCP Reno and TCP Vegas, TCP New Reno over TCP Reno, when they share the same bottleneck link at the router. For instigating this situation, we used drop-tail and RED algorithm at the router and used NS-2 simulator for simulation. From the simulation results, we have observed that the performance of TCP Reno and TCP Vegas is different in two cases. In drop tail algorithm, TCP Reno achieves better Performance and throughput and act more an aggressive than Vegas. In Random Early Detection (RED) algorithm, both of congestion control mechanism provides better fair service when they coexist at the same link. TCP NewReno provides better performance than TCP Reno. Keywords — Drop-tail algorithm, Fairness, RED, TCP Congestion control. sending and receiving transmission rate when congestion I.
    [Show full text]
  • TCP in Manets – Challenges and Solutions
    FFI-rapport 2012/01289 TCP in MANETs – challenges and Solutions Erlend Larsen Norwegian Defence Research Establishment (FFI) 27 September 2012 FFI-rapport 2012/01289 1175 P: ISBN 978-82-464-2133-9 E: ISBN 978-82-464-2134-6 Keywords Mobile Ad Hoc Nettverk Metningskontroll Transportprotokoll Approved by Torunn Øvreås Project Manager Anders Eggen Director 2 FFI-rapport 2012/01289 English summary Mobile Ad hoc NETworks (MANETs) have gained significant popularity through the last decade, not least due to the emergence of low cost technology and the pervasiveness of the IP protocol stack. The FFI-project 1175, ”Gjennomgaende˚ kommunikasjon for operative enheter”, is chartered with researching MANETs for use by the Norwegian operational military forces. Self-organizing and self-healing wireless multihop networks, MANETs are aimed at supporting tactical domain communications with a high grade of mobility. These networks will interconnect with other networks in the Networking and Information Infrastructure (NII) using IP as the common connecting protocol. The Transmission Control Protocol (TCP) is ”the protocol that saved the Internet”, most importantly because of its congestion control mechanism. It is a vital building stone in IP-based networks, but it faces serious challenges when used in MANETs, since MANETs are challenged with interference and high grade of mobility, from which wired networks are spared. Thus, to employ MANETs interconnected in the defense communication infrastructure, it is important to study the problems and the current state of the art of TCP in MANETs. This report is aimed at introducing readers to the TCP protocol, describing the challenges that TCP faces in MANETs, and give an overview of ongoing research to adapt TCP to MANETs.
    [Show full text]
  • Scenario Based Performance Analysis of Variants of TCP Using NS2-Simulator
    International Journal of Advancements in Technology http://ijict.org/ ISSN 0976-4860 Scenario Based Performance Analysis of Variants of TCP using NS2-Simulator Yuvaraju B. N, Niranjan N Chiplunkar Department of Computer Science and Engineering NMAM Institute of Technology, Nitte - 574110, Karnataka, INDIA. [email protected], [email protected] Abstract The increasing demands and requirements for wireless communication systems especially in settings where access to wired infrastructure is not possible like natural disasters, conferences and military settings have led to the need for a better understanding of fundamental issues in TCP optimization in MANETS.TCP primarily designed for wired networks, faces performance degradation when applied to the ad-hoc scenario. Earlier work in MANETs focused on comparing the performance of different routing protocols. Our analysis is on performance of the variants of TCP in MANETS. Several different variants have been developed in order to refine congestion control in Mobile Adhoc Networks. These variants of TCP perform better under specific scenarios, our Analysis of the variants of TCP is based on three performance metrics: TCP Throughput ,Average End- to -End delay and Packet Delivery Fraction in high and low mobility. This analysis will be useful in determining the better variant among TCP Protocols to ensure better data transfer, speed, and reliability and congestion control. In this paper we carry out performance study of six variants of TCP to be able to classify which variant of TCP performs better in various possible scenarios in MANETs. Keywords: Ad-hoc Networks, Congestion and Mobile Relays. 1. Introduction Effectively and fairly allocating the resources of a network among a collection of competing users is a major issue.
    [Show full text]
  • CSCI-1680 Transport Layer III Congestion Control Strikes Back
    CSCI-1680 Transport Layer III Congestion Control Strikes Back Rodrigo Fonseca Based partly on lecture notes by David Mazières, Phil Levis, John Janno<, Ion Stoica Last Time • Flow Control • Congestion Control Today • More TCP Fun! • Congestion Control Continued – Quick Review – RTT Estimation • TCP Friendliness – Equation Based Rate Control • TCP on Lossy Links • Congestion Control versus Avoidance – Getting help from the network • Cheating TCP Quick Review • Flow Control: – Receiver sets Advertised Window • Congestion Control – Two states: Slow Start (SS) and Congestion Avoidance (CA) – A window size threshold governs the state transition • Window <= ssthresh: SS • Window > ssthresh: Congestion Avoidance – States differ in how they respond to ACKs • Slow start: +1 w per RTT (Exponential increase) • Congestion Avoidance: +1 MSS per RTT (Additive increase) – On loss event: set ssthresh = w/2, w = 1, slow start AIMD Fair: A = B AI MD Flow Rate B Efficient: A+B = C Flow Rate A States differ in how they respond to acks • Slow start: double w in one RTT – Tere are w/MSS segments (and acks) per RTT – Increase w per RTT à how much to increase per ack? • w / (w/MSS) = MSS • AIMD: Add 1 MSS per RTT – MSS/(w/MSS) = MSS2/w per received ACK Putting it all together cwnd Timeout Timeout AIMD AIMD ssthresh Slow Slow Slow Time Start Start Start Fast Recovery and Fast Retransmit cwnd AI/MD Slow Start Fast retransmit Time TCP Friendliness • Can other protocols co-exist with TCP? – E.g., if you want to write a video streaming app using UDP, how to do congestion control? 10 9 8 RED 1 UDP Flow at 10MBps 7 6 31 TCP Flows 5 Sharing a 10MBps link 4 3 2 Throughput(Mbps) 1 0 1 4 7 10 13 16 19 22 25 28 31 Flow Number TCP Friendliness • Can other protocols co-exist with TCP? – E.g., if you want to write a video streaming app using UDP, how to do congestion control? • Equation-based Congestion Control – Instead of implementing TCP’s CC, estimate the rate at which TCP would send.
    [Show full text]