Performance Modeling of Computer Networks - Introduction

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1 Performance Modeling of Computer Networks - Introduction What this course is all about, what you will learn and how you use it in real life Sandip Chakraborty Department of Computer Science and Engineering, INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR July 17, 2017 Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

2 An Example Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

3 Objective of the Course Broad Objective To understand the behavior of different network components (hardware and their interconnections, protocols etc) and apply them to refine or boost up the network behavior Image Source: Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

4 What are the ways to understand the behavior of a Network Protocol? Implement it on a network testbed and check its performance. Difficult to check the scalability of the protocol - global implementation is not possible For many of the early network protocols (like IP, TCP) people have first implemented those, and then understood their shortcomings - large amount of network resources are wasted to maintain this backward compatibility Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

5 What are the ways to understand the behavior of a Network Protocol? Implement it on a network testbed and check its performance. Difficult to check the scalability of the protocol - global implementation is not possible For many of the early network protocols (like IP, TCP) people have first implemented those, and then understood their shortcomings - large amount of network resources are wasted to maintain this backward compatibility Simulate the behavior over a simulation framework (like NS-3, Qualnet, Opnet etc.) Simulators can not capture the real network conditions. Also the implementations may be questionable as the framework is seldom globally verified. Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

6 What are the ways to understand the behavior of a Network Protocol? Implement it on a network testbed and check its performance. Difficult to check the scalability of the protocol - global implementation is not possible For many of the early network protocols (like IP, TCP) people have first implemented those, and then understood their shortcomings - large amount of network resources are wasted to maintain this backward compatibility Simulate the behavior over a simulation framework (like NS-3, Qualnet, Opnet etc.) Simulators can not capture the real network conditions. Also the implementations may be questionable as the framework is seldom globally verified. Model the protocol mathematically, and analyze its behavior to understand its internals It is extremely difficult to capture all the dynamics - several assumptions are made to simplify the analysis Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

7 What are the ways to understand the behavior of a Network Protocol? Implement it on a network testbed and check its performance. Difficult to check the scalability of the protocol - global implementation is not possible For many of the early network protocols (like IP, TCP) people have first implemented those, and then understood their shortcomings - large amount of network resources are wasted to maintain this backward compatibility What is the best way? Simulate the behavior over a simulation framework (like NS-3, Apply Qualnet, all theopnet three etc.) methods together to do a rigorous analysis Simulators can not capture the real network conditions. Also the implementations may be questionable as the framework is seldom globally verified. Model the protocol mathematically, and analyze its behavior to understand its internals It is extremely difficult to capture all the dynamics - several assumptions are made to simplify the analysis Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

8 What you ll learn in this course How to characterize a network protocol? What parameters affect the behavior of a network protocol? Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

9 What you ll learn in this course How to characterize a network protocol? What parameters affect the behavior of a network protocol? How to verify that a protocol is correct (it ll do what it intends to do)? Say, you are designing a FAIR channel access protocol. How can you ensure that the protocol indeed provides fairness. Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

10 What you ll learn in this course How to characterize a network protocol? What parameters affect the behavior of a network protocol? How to verify that a protocol is correct (it ll do what it intends to do)? Say, you are designing a FAIR channel access protocol. How can you ensure that the protocol indeed provides fairness. How can you find out (guess or say something about) the performance of a network protocol? Example: How TCP will behave over a 4G (LTE) network? Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

11 What you ll learn in this course How to characterize a network protocol? What parameters affect the behavior of a network protocol? How to verify that a protocol is correct (it ll do what it intends to do)? Say, you are designing a FAIR channel access protocol. How can you ensure that the protocol indeed provides fairness. How can you find out (guess or say something about) the performance of a network protocol? Example: How TCP will behave over a 4G (LTE) network? With this knowledge of network performance (or protocol behavior), how can you tune the protocol for a given network scenario? Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

12 What you can do with this knowledge Understand the limitation of current network protocols and what are the requirements for future network protocols. Optimize the use of network resources - network planing The cellular network companies/service providers are very much interested to find out the optimal deployment of cellular base stations for maximizing performance-capex-cost trade-off. Can you design one? Exploit the internals of a network protocol Design a new security attack Prevent a security vulnerability Make the network INTELLIGENT (Cognitive Networks - You ll learn more later on!) Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

13 The bad thing is that we have to do some mathematics for all these stuffs! Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

14 Don t think this is a pure mathematical course! We ll apply the knowledge of mathematics over computer systems (specifically networks) and learn/design new aspects of it... Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

15 Contents of this course We ll cover the mathematical pre-requisites as a part of this course: Network Optimization: Network resource allocation Stochastic Modeling: Network resource allocation Game Theory and online learning: Network intelligence Petri-nets, Formal modeling: Protocol verification We ll apply this knowledge in different protocols span over different domains (wired/wireless; mobile/cellular etc) Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

16 Classroom/Exam Policies In the classroom: Discuss the basic mathematical pre-requisites along with how to apply them Out the classroom: I ll periodically post some practice problems, try to solve them in groups Class discussion and problem solving: We ll collectively try to solve some unsolved problems! Term Paper: In a group of maximum two select a problem and try to solve! (TAs and instructors will help) Grading Policy: Mid Sem (25%), End Sem(45%), Term paper, Class discussion and problem solving assignments (30%) Expectations from students: Make the class-room interactive! Feel free to ask question. No question is a bad question. Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

17 Why Both Assignments and Term Papers? Assignments are for understanding existing ideas Term papers are for innovating new ideas. Many good publications from previous term papers, Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

18 Why Both Assignments and Term Papers? Assignments are for understanding existing ideas Term papers are for innovating new ideas. Many good publications from previous term papers, Kumar Ayush, Varun Rawal, Raja Karmakar, Pradyumna Kumar Bishoyi, Samiran Chattopadhyay and Sandip Chakraborty, Supporting Throughput Fairness in IEEE ac Dynamic Bandwidth Channel Access: A Hybrid Approach, in proc. of the 42nd Annual IEEE Conference on Local Computer Networks (IEEE LCN 2017), Singapore, October 09-12, 2017 (Acceptance Rate: 25%) Satadal Sengupta, Vinay Kumar Yadav, Yash Saraf, Harshit Gupta, Niloy Ganguly, Sandip Chakraborty, Pradipta De, MoViDiff: Enabling Online Service Differentiation for Mobile Video Apps, in proc. of the Mini-Conference track of the 2017 IFIP/IEEE International Symposium on Integrated Network Management (IM 2017), Lisbon, Portugal, May 08 - May 12, 2017 (Acceptance rate: 16.88%) Kumar Saurav, Kartik Vermun, and Sandip Chakraborty, Adaptive Redistribution of Resources for Ensuring Service Quality in a Post Disaster Situation Analysis Network, in proc. of the IEEE International Conference on Advanced Networks and Telecommunications Systems (IEEE ANTS 2016), Bangalore, India, November 06-09, 2016 (Acceptance Rate: 26%) Gurman Bhalla, Raja Karmakar, Sandip Chakraborty, and Samiran Chattopadhyay, CrowdAP: Crowdsourcing Driven AP Coordination for Improving Energy Efficiency in Wireless Access Networks, in proc. of the IEEE International Conference on Communications (IEEE ICC 2016) - Green Communications Systems and Networks, Kuala Lumpur, Malaysia, May 23-27, 2016 (Acceptance Rate: 30%) Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

19 Classroom/Exam Policies Feedback: Two anonymous feedbacks will be taken - mid-term (by the course instructor) and end-term (by the institute). Always feel free to share your expectations. Contact me for any doubts/clarifications/suggestions. Attendance: Institute attendance policy would be followed. Poor attendance may result in de-registration. Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

20 Books/Study Materials Michal Pioro, Deepankar Medhi, Routing, Flow and Capacity Design in Communication and Computer Networks, Morgan Kaufman Publishers Anurag Kumar, D. Manjunath and Joy Kuri, Communication Networking: An Analytical Approach, Morgan Kaufman Publishers Dimitri P. Bertsekas and Robert G. Gallager, Data Networks Research Publications - will be discussed and distributed time to time Lecture notes - will be published in the course website Course website: CS_60019_Autumn_2017.html Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

21 Teaching Assistants Satadal Sengupta ac.in CNeRG Lab Abhijit Mondal Systems and Mobile Research Lab Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

22 Class Timings Slot H3, Classroom: CSE-120 MON 02:00 pm - 02:55 pm TUE 04:00 pm - 05:55 pm Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14

23 Thank You Sandip Chakraborty (IIT Kharagpur) CS July 17, / 14