CS 118 Computer Network Fundamentals u Instructor Songwu

CS 118: Computer Network Fundamentals u. Instructor: Songwu Lu (slu@cs. ucla. edu) – Office hours: 4: 00 -5: 00 Tue, 9: 00 -10: 00 Thur – Office: 4531 D BH u. TAs: – Nicolas Bertolami (berto@cs. ucla. edu) & Yu Uny Cao (yu@cs. ucla. edu) – Mailbox: 4428 BH u. Course homepage: – http: //www. cs. ucla. edu/classes/spring 00/cs 118/ u. Course newsgroup – ucla. classes. cs 118 CS 118/Spring 2000 1 4/3/00

Why are you sitting in this class? ? u. A few reasons: – “CS 118 is a requirement for my degree” – “I need 4 more units to graduate, and CS 118 seems the least evil among all the options” – “Probably useful for my job interview” – “If Internet is so hot now, I want to learn something about the Internet” – “I want to enter graduate school, and networking area is one of my options” – …. . . CS 118/Spring 2000 2 4/3/00

What can you learn from this course? u. Understand the basics of computer networks: design and practice u. Learn the basics of TCP/IP protocol suite in the current Internet u. Develop network programming skills CS 118/Spring 2000 3 4/3/00

Outline for this lecture u. Course online! information: everything will be – prerequisite – course workload – course grading policy – TA sections – course newsgroup and homepage u. Introduction CS 118/Spring 2000 to computer networks 4 4/3/00

Immediate Suggestions You are highly recommended to usubscribe to class newsgroup immediately: ucla. classes. cs 118 udownload lecture notes before each lecture – notes go online before the lecture ucheck the class homepage & newsgroup regularly (daily or bi-daily) – assignments are posted onto the homepage on Thursdays – other updates & notices are posted regularly CS 118/Spring 2000 5 4/3/00

Course Requirements u. Prerequisites – Upper division standing – Course work on (or experience with) computer architecture & operating systems – programming experience in C/Unix u. Required textbook: Computer Networks, A Systems Approach (2 nd edition) u. Recommended reference book: TCP/IP Illustrated, Vol. 1 by R. Stevens CS 118/Spring 2000 6 4/3/00

Course Workload u. Reading assignment for every lecture – mostly from textbook, plus occasional handouts u. Assignment – homeworks + machine assignments u. Programming projects u. Midterm and final exams u. Classroom participation CS 118/Spring 2000 7 4/3/00

Assignments u. Five homeworks + 2 Machine assignments – Machine assignments: learn – homeworks are given out on Thursdays, and they are due 12: 00 pm next Friday to TA's mailbox in 4428 Boelter Hall – you have about ten days to work out each machine assignment (posted on Mon/Tues, due on Fridays the following week) – you are expected to work out these assignments individually (no collaboration please)! CS 118/Spring 2000 8 4/3/00

Programming Projects u. Three programming projects – #1: introduction to network programming (3 weeks) – #2: developing a simple network protocol – #3: building a simple network application u. Two-person group project – each group has exactly two students – start to find your project partner immediately! u. Work CS 118/Spring 2000 out your projects in C/Unix 9 4/3/00

Course Grading and Policies u. Grading breakdown Homework 20% Project 30% Midterm 20% Final exam 30% ugrading based on curves uno late turn-in will be accepted for credit uno make-up exams no misconduct CS 118/Spring 2000 10 4/3/00

TA Sections u. Friday’s recitation – 12: 00 pm -- 1: 50 pm, Friday; 5280 BH – 4: 00 pm -- 5: 50 pm, Friday; 5440 BH u. TBA – TA sections homepage – TA office hours CS 118/Spring 2000 11 4/3/00

Newsgroup and Homepage u. Newsgroup – Post your questions to the newsgroup, TAs and I will answer them regularly – Please do NOT post detailed programming codes onto the newsgroup unless you get approval from me or the TAs! u. Homepage – check out the assignments, lecture notes, etc. regularly – If you have other interesting resources (e. g. , a useful network programming hyperlink, let us know) CS 118/Spring 2000 12 4/3/00

What this course will cover What are the underlying concepts and technologies that make the Internet work? u. What are the "network protocols", protocol design and implementations u. Basic concepts & principles, lots of practice – your reading assignment will include several protocol specifications for some basic Internet standard protocols – programming projects; machine assignments also require programming effort CS 118/Spring 2000 13 4/3/00

What this course will not cover: u. Hardware u. Communication theory – AM/FM modulation – coding theory u. Queuing theory – topic of CS 112 u. Survey of all network protocols – OSI model – ATM CS 118/Spring 2000 14 4/3/00

Some basic concepts u. Networks: telephone network , cable TV network u. Computer networks: a set of computers connected by switches & communication links so that they can talk to each other. – Fundamental feature: seek to serve all types of computer applications – information sharing u. Internet: an interconnection of computers using the Internet Protocol (IP) suite CS 118/Spring 2000 15 4/3/00

Cost-effective resource sharing u. Multiplexing: multiple data streams share one communication channel L 1 R 1 L 2 R 2 L 3 u. Statistical Switch 1 Switch 2 multiplexing Packet (carries destination address) CS 118/Spring 2000 Switch 1 16 Switch 2 4/3/00 R 3

u. Why Reasons. . . multiplexing? – Multiple users share resources – contending for shared resources u. Three types of multiplexing – time-division multiplexing: synchronous & asynchronous – frequency-division multiplexing – statistical multiplexing u. Why statistical multiplexing for data app. ? – On-demand resource allocation for bursty traffic – limit the channel sharing time of each data application: variable but bounded packet size CS 118/Spring 2000 17 4/3/00

Packet Switched Networks u. Hosts send data in packets unetwork supports all data communication services by delivering packets – Web, email, multimedia Host video Application Host Web Host email CS 118/Spring 2000 18 4/3/00

One network application example Dave@cs. ucla. edu msg CS 118/Spring 2000 Jim@lcs. mit. edu 19 4/3/00

One network application example Dave@cs. ucla. edu msg email Jim@lcs. mit. edu Transport protocol Network protocol Physical net CS 118/Spring 2000 Network protocol Physical net 20 Network protocol physical net 4/3/00

Match protocol pieces to real boxes: Email program Dave's computer transport protocol Internet Ethernet driver Jim's computer Ethernet card CS 118/Spring 2000 21 4/3/00

Layered Network Architecture unetwork consists of geographically distributed hosts and switches (nodes) u. Nodes communicate with each other by standard protocols host A switch A B C D B physical connectivity Protocol layers network topology CS 118/Spring 2000 C 22 4/3/00

a picture of protocol layers A Application (data) header data Transport segment header DATA network packet DATA header Ethernet frame tail B physical connectivity What’s in the header: info needed for the protocol’s function CS 118/Spring 2000 23 4/3/00

Course Outline: 1. Introduction (Ch 1) Basic network components ulinks: coaxial cable, twisted pair, optical fiber, radio, satellite…… – their data transmission properties uswitches: mostly special boxes – can also be general-purpose computers u. Host: CS 118/Spring 2000 workstations, PC’s, laptops. . . 24 4/3/00

2. Data link layer and LAN’s (Ch 2, 3) u. Point-to-point links – how to send data over such a link u. Multi-access u. Bridges: together CS 118/Spring 2000 LAN’s (Local Area Network) switches that connect LAN's 25 4/3/00

3. Internetwork (Ch 4) ua network can be defined recursively – two or more nodes connected by point-to-point links make a network – two or more networks connected by routers make an internet u. IP: Internet Protocol CS 118/Spring 2000 26 4/3/00

4. Network routing protocols (Ch 4) u. Network address: a bit string that uniquely identifies a connecting point in the network u. Network routing: determining where to forward packets towards the destination node identified by the address uunicast routing sender umulticast routing (Midterm exam) CS 118/Spring 2000 27 4/3/00

5. The transport layer (Ch 5) u. How to provide reliable data delivery over unreliable channels u. TCP: Transmission Control Protocol 6. Advanced topics (Ch 6, 9) u. Network congestion control u. Application examples: email, Web CS 118/Spring 2000 28 4/3/00

What to do after this class u. Subscribe to the class newsgroup ufinish reading assignment before next lecture ustart to look for your project partner ustart reading the network programming tutorial posted in the course homepage CS 118/Spring 2000 29 4/3/00

Important question to think about. . . uwhat makes the Internet so popular these days? – Fundamental driving force: human/society’s communication need – The fuel for the Internet growth: the chips, and optical fiber – Fundamental enabler: the Internet Protocol architecture (focus of this course) – The future? u. Interesting articles on Internet histories – http: //www. isoc. org/internet-history (see homepage) CS 118/Spring 2000 30 4/3/00