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Transcript
Communication Networks A Second Course Jean Walrand Department of EECS University of California at Berkeley Administrative Details • 3 Units • Course Contents: • Review major recent networking research ideas • Provide background for these papers • Get a sense of where field is heading • Grade based on • Class participation: Writing lecture notes: • Lecture assigned “scribe” writes notes other students send comments on notes revised notes • Term project and its presentation: • Select topic by week 6; outline by week 9; ready to present by week 12; report by week 15. Contents • • • • • • Introduction Review of TCP/IP Moving Forward Wireless Networks Transport Incentives Introduction • • Explain network models and analysis Focus on three active areas of research 1. Wireless: Wi-Fi, Wi-Max, MANETs, Sensors 2. QoS, Transport, Routing, Cross-Layer… 3. Incentives: Differentiation, Revenue Sharing … • Along the way, we cover some useful tools • • • • Markov models Stability of nonlinear systems Duality in convex programming Game theory Introduction • Major developments in Internet and networks • • • • • • Economic value (B2B, B2C) New applications (voice, video, TV) New structures (P2P) Machine-to-machine communication Mobility support Security concerns • Internet protocols over-stretched • Protocols must adapt or be changed Introduction • Key Ideas: Introduction • Major research topics ARCHITECTURE Security Mobility Economics Management Applications Network Transport MIDDLEWARE Sensor Networks Link/PHY Service Model Packets/VC/C/… Names, Addresses Compatibility Structure PROTOCOL FUNCTIONS WIRELESS GENERAL VoIP - Streaming Ad Hoc Applications Sensor/Actuators Transport for Ad Hoc QoS Routing Network Processing Combining Networks Parallel Paths TDM/Reservation Multi-Channel Low energy Cognitive Relays, MIMO, Capacity Overlay Searching P2P Storage Fast Transport over fast links Service Differentiation QoS Routing Improved BGP Optical Packets, Bursts, Lambda Introduction • Architecture • • • • Service Model: Best effort or richer? Compatible or “Greenfield” New layer structure for wireless, “cross-layer?” Switching and transport modes Introduction • Architecture: Service Specification: soft or precise? Choice and select? Introduction • Architecture: Layers n Interface n Interface C’ C n-1 Services I’ I n-1 H H Services Introduction • Architecture: Mode Packet MPLS BURST Lambda BURST MPLS Packet Introduction • Middleware • • • • Economics: Differentiation, Revenue Sharing QoS: Specified or end-to-end choice Mobility: Indirection Name Address Security: Insurance? Introduction • Middleware: Differentiation Premium - $0.1/min Basic - free Introduction • Middleware: QoS • Specified: Premium = less than 150ms • Choice: premium better than basic… Introduction • Middleware: Mobility • Indirection (similar to cell phone) Bill (3): Bill = ? To H(Bill) D = H(Bill) (1) A (e.g., DHCP) Bill: A (4): Bill = A (2): Bill = A to H(Bill) Introduction • Middleware: Security • Insurance? To connect, you need an insurance Insurance company checks your “security” Incentive: Premium goes down if secure Introduction • Wireless: • Sensor and Ad Hoc • • • • • • • • Application-driven or generic? Network capacity Scheduling: graph coloring Power control: strategic issues Routing: interference; short or long hops; parallel paths Transport: How to include graph constraints? Network-processing Network coding • Wi-Fi • VoIP+Data Capacity • WiMax vs. Wi-Fi Introduction • Wireless: Application-Driven or Generic? • Basic observation: No universally best protocols • Using features of application yields better solutions • Example 1: If central node can reach all sensors, it can provide synchronization, polling, etc. • Example 2: Power constraints may not exist in some systems and be essential in others • Keep in mind technology trends Introduction • Wireless: Network Capacity • • • • Random network or given network? O(.)-results or precise results? Optimal or given set of protocols? Delay-constrained or not? Introduction • Wireless: Scheduling • • • • Graph coloring Key issue: correct model of constraints Difficulty: Interference;Uncertainties Question: Complexity (time, communication) 1, 4 2, 5 3, 5 1, 3 2, 4 Introduction • Wireless: Power Control • Strategic: In CDMA, increasing a improves rate for node but increases interference for others a c b Introduction • Wireless: Routing • Principle of optimality fails…. • Short or long hops? Introduction • Wireless: Transport • Constraints? Assume CDMA or TDMA? Introduction • Wireless: Network Processing • Complexity 1 1 4 7 7 Max(1, 4, 7) 5 2 8 Max(3, 6, 9) 3 3 6 6 9 Introduction • Wireless: Network Coding • Worthwhile? 1 1 2 2 1 2 1+2 3 1+2 4 Introduction • Wired • • • • • Overlay pros and cons P2P incentives Transport: Control problem, strategic aspects Service differentiation: benefits Routing: BGP, QoS, Strategic aspects