1OverviewEECS 122: Lecture 1Department of Electrical Engineering and Computer SciencesUniversity of CaliforniaBerkeleyJanuary 17, 2006EECS122 Lecture 1 (AKP)2Today’s Outline Course Information and Goals Overview Applications, Protocols and Components The Network Edge and Core Divsion Packet and Circuit Switching Examples of Networks What is the Internet? Great way to familiarize you with some terms and concepts The rest of course will delve deeper into what you hear about today…January 17, 2006EECS122 Lecture 1 (AKP)3Administrivia Instructors Abhay Parekh ([email protected], 223 Cory) David Tse ([email protected], 224 Cory) TAs Marghoob Mohiyuddin (marghoob@eecs, Office hours: TBA) Nikhil Shetty (nikhils@eecs, Office Hours: TBA) Recitations: W F Lecture time Tues/Thursday, 12:30 – 2pm Office hour: Tues/Thursday, 2-3pm in the Qualcomm Room (200 Cory) Class Web page http://inst.eecs.berkeley.edu/~ee122/ (not up yet) Text Computer Networking: A Top Down Approach Featuring the Internet (3rdEdition) by Kurose and RossJanuary 17, 2006EECS122 Lecture 1 (AKP)4Course Structure Prerequisites: C and Java (you don’t have to be a great programmer, but comfortable with the syntax) Algorithms and their analysis – no difficult math, but you have to be comfortable looking at problems analytically Grading Homework Assignments: 15% Projects: 30% Midterm: 20% Final: 35% Homework: Paper-pencil problems and “Ethereal Lab” problems Projects: Network Simulator (NS2) based project Several shorter programming projects based on C and Java2January 17, 2006EECS122 Lecture 1 (AKP)5Course Structure This is a big class so please Attend Lecture Be on Time Ask Questions Utilize the course resources: Lectures, Recitations, Labs, Office Hours, Companion Website for the book Networking is a very complex subject try to focus on concepts, not just details. Late Hand-ins: 25% off for the first late day Nothing accepted that is more late than one dayJanuary 17, 2006EECS122 Lecture 1 (AKP)6What is networking?RoutersTCP/IPFree Stuff802.11WWWP2POptical FiberIMCable ModemhttpVoice/DataJanuary 17, 2006EECS122 Lecture 1 (AKP)7ApplicationsRoutersTCP/IPFree Stuff802.11WWWP2PCable ModemIMOptical FiberhttpJanuary 17, 2006EECS122 Lecture 1 (AKP)8ComponentsRoutersTCP/IPFree Stuff802.11WWWP2PCable ModemIMOptical Fiberhttp3January 17, 2006EECS122 Lecture 1 (AKP)9ProtocolsRoutersTCP/IPFree Stuff802.11WWWP2PCable ModemIMOptical FiberhttpJanuary 17, 2006EECS122 Lecture 1 (AKP)10What’s a protocol?human protocols: Meal time “I have a question” introductions… specific msgs sent… specific actions taken when msgs received, or other eventsnetwork protocols: machines rather than humans all communication activity in Internet governed by protocolsprotocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receiptJanuary 17, 2006EECS122 Lecture 1 (AKP)11Sure! Over and outLet’s hang up, OverWhat’s a protocol?a human protocol and a computer network protocol:Hi, OverHello, OverTCP connectionrequestTCP connectionresponseGet http://www.berkeley.edu<file>timeJanuary 17, 2006EECS122 Lecture 1 (AKP)12Applications, Protocols, Components…How do they all come together? Our Focus will be on the internet What is its structure? How does it scale? Who owns it? How can we make it better? How does one write a new network application? How does one insert a new component (a faster router for example)? This will help us understand other kinds of networks (e.g. the voice network) as well4January 17, 2006EECS122 Lecture 1 (AKP)13Course Goals To gain a fundamental understanding of what the internet is and how it works today This is a “first course” so we may be more wide than deep! To understand how the internet may evolve in the futureJanuary 17, 2006EECS122 Lecture 1 (AKP)14The Simplest Network…A BHostsLinkJanuary 17, 2006EECS122 Lecture 1 (AKP)15Networks are created from a need to communicate…SkypePhonesWeb ServersHundreds of Millions of End Nodes or HostsJanuary 17, 2006EECS122 Lecture 1 (AKP)16Inevitably, Networks GrowAB1. The forwarding function becomes a performance bottleneck 2. There too many alternative paths – the overhead to select among them becomes prohibitiveC EDDirectly connectingn hosts takes O(n2) links!Complications: Hosts1. must forward2. choose among multiplepaths5January 17, 2006EECS122 Lecture 1 (AKP)17Enter Routers…ABHosts connect to specialized devices called Routers. Routers are built (HW and Software) to discover the topology, select good paths and forward messagesquickly. They respond to changing network conditions.C EDJanuary 17, 2006EECS122 Lecture 1 (AKP)18Enter Routers…ABHosts connect to specialized devices called Routers. Routers are built (HW and Software) to discover the topology, select good paths and forward messagesquickly. They respond to changing network conditions.C EDJanuary 17, 2006EECS122 Lecture 1 (AKP)19Enter More Network InfrastructureABC EDA directory server that helps an applicationnode figure out which network address(es) it shouldsend its messages to.In the internet, this is DNSJanuary 17, 2006EECS122 Lecture 1 (AKP)20Host-Core DivisionABThe devices inside the network cloud are what makethe internet tickThe applications in end hosts make the internet useful and powerful •The end hosts form the Network EdgeC EDThe Core providesa network service to the hosts6January 17, 2006EECS122 Lecture 1 (AKP)21Special Case: BroadcastABC EDDirectly connectingn hosts takes O(n2) links!Every transmission is received by all the other hostsExamples:1. Satellite Transmission2. Local Area NetworksThe core is very simplefor broadcast networksalthough other problems(to be studied later) ariseJanuary 17, 2006EECS122 Lecture 1 (AKP)22The network edge: client/server model client host requests, receives service from always-on server e.g. Web browser/server; email client/server peer-peer model: minimal (or no) use of dedicated servers e.g. Gnutella, KaZaA, SkypeJanuary 17, 2006EECS122 Lecture 1 (AKP)23The Network Core Many interconnected “sub-networks” Many different architectures Advertises a “service” to the end devices E.g. Phone network v/s the InternetJanuary 17, 2006EECS122 Lecture 1
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