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CMPE 150- Introduction to Computer Networks 1 CMPE 150 Fall 2005 Lecture 1 Introduction to Computer Networks.

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Presentation on theme: "CMPE 150- Introduction to Computer Networks 1 CMPE 150 Fall 2005 Lecture 1 Introduction to Computer Networks."— Presentation transcript:

1 CMPE 150- Introduction to Computer Networks 1 CMPE 150 Fall 2005 Lecture 1 Introduction to Computer Networks

2 CMPE 150- Introduction to Computer Networks 2 Class Information Class time and location: –M, W, F from 2:00 – 3:10. –E2 180 Class Web page: –http://www.cse.ucsc.edu/classes/cmpe150/Fall05 Instructor: –Katia Obraczka –E2 323 –Office hours: TBD

3 CMPE 150- Introduction to Computer Networks 3 Class Information Teaching Assistant –Sudharsan Rangarajan Lab Assistants –Jay Boice –Todd Nagengast

4 CMPE 150- Introduction to Computer Networks 4 Textbook

5 CMPE 150- Introduction to Computer Networks 5 Pre-requisites CMPE 16 CMPE 12C/L

6 CMPE 150- Introduction to Computer Networks 6 Focus Intro to data networks from an engineering perspective. Broad coverage. –Network architectures. –Network protocols, –Layered design. –Protocol stack. –TCP/IP and the Internet, Hands-on aspect.

7 CMPE 150- Introduction to Computer Networks 7 Topics Covered Introduction and Overview. Physical Layer. Medium Access Control (MAC). Link Layer. Network Layer. Routing. Internetworking and IP. IP Routing and Control. Transport Layer. Application Layer. Putting It All Together!

8 CMPE 150- Introduction to Computer Networks 8 Other Networking Courses CE 151Network Administration CE 152Protocols CE 156Network Programming CE 107 Stochastic System Analysis EE 103Signals and Systems CE 154Data Communication CE 153Digital Signal Processing EE 151Communications Systems CE 108 Data Compression CE 163 Multimedia CS 111Operating Systems

9 CMPE 150- Introduction to Computer Networks 9 Grading Mid-term 35% Assignments 25% –Homework –Labs Final 40% No credit for work that is not your own.

10 CMPE 150- Introduction to Computer Networks 10 Academic Integrity Academic integrity policies will be strictly enforced! Academic integrity policy violations will NOT be tolerated!

11 CMPE 150- Introduction to Computer Networks 11 Course Outline Introduction –History, basic concepts, terminology. –More, not-so-basic concepts:protocols, layering,, etc. Physical layer –Transmitting data. Data link layer –Reliable transmission. –Accessing the communication medium Medium access control protocols. LANs –Ethernet, token ring, wireless LANs.

12 CMPE 150- Introduction to Computer Networks 12 Course Outline (contd) Network layer –Types of network services. –Circuit- vs. packet switching. –Virtual circuits and datagrams. –Routing. –Addressing. –Unicast and multicast. Internetworking –IP. –The Internet. –IP Routing and Control.

13 CMPE 150- Introduction to Computer Networks 13 Course Outline (contd) Transport layer –E2E communication.. –Types of transport service. –Connectionless versus connection-oriented. –UDP. –TCP. Application layer –DNS, ssh, telnet, ftp, news, . –The Web. HTTP. HTML. Search engines. Proxy and caches –Peer-to-peer. –Security.

14 CMPE 150- Introduction to Computer Networks 14 Whats a network?

15 CMPE 150- Introduction to Computer Networks 15 Whats a network? Merriam-Webster Dictionary: –|A fabric or structure of cords or wires that cross at regular intervals… –A system of computers, terminals and databases connected by communication lines A computer network is defined as the interconnection of 2 or more independent computers. [Ramteke,Networks, pg. 24].

16 CMPE 150- Introduction to Computer Networks 16 Why network? Before networks: –One large computer (mainframe) used for all processing in businesses, universities, etc. Smaller, cheaper computers… –Personal computers or workstations on desktops. –Interconnecting many smaller computers is advantageous! Why?

17 CMPE 150- Introduction to Computer Networks 17 Ubiquitous Computing Computers everywhere. Also means ubiquitous communication. –Users connected anywhere/anytime. –PC (laptop, palmtop) equivalent to cell phone. Networking computers together is critical!

18 CMPE 150- Introduction to Computer Networks 18 Computer Network Provide access to local and remote resources. Collection of interconnected end systems: –Computing devices (mainframes, workstations, PCs, palm tops) –Peripherals (printers, scanners, terminals).

19 CMPE 150- Introduction to Computer Networks 19 Why network? Resource sharing! –Hardware: printers, disks, terminals, etc. –Software: text processors, compilers, etc. –Data. Robustness. –Fault tolerance through redundancy. Load balancing. –Processing and data can be distributed over the network. Location independence. –Users can access their files, etc. from anywhere in the network.

20 CMPE 150- Introduction to Computer Networks 20 Problems? Security! –Its much easier to protect centralized resources than when they are distributed. –Network itself as the target..

21 CMPE 150- Introduction to Computer Networks 21 Some History

22 CMPE 150- Introduction to Computer Networks 22 Before the Internet Postal network. –Delivers different types of objects (letters, packages, etc.) world-wide. –Relatively high delay but relatively cheap. –Sender and receiver identified by their postal address (name, number, street, city, etc.). Telephone network. –Engineered to deliver real-time voice. –Also world-wide. –Low delay but more expensive. –Users identified but telephone number.

23 CMPE 150- Introduction to Computer Networks 23 The Telephone Network

24 CMPE 150- Introduction to Computer Networks 24 The Telephone Network Telephone was patented by G. Bell in For one telephone to be able to talk with another telephone, a direct connection between the two telephones was needed. –Within one year, cities were covered with a wild jumble of wires!

25 CMPE 150- Introduction to Computer Networks 25 The Telephone Network (contd) In 1878, the Bell Telephone company opened its first switching office (in New Haven, CT). Each user would connect to the local switching office. –When a user wanted to make a call, s/he rang to the office, and would be manually connected to the other end.

26 CMPE 150- Introduction to Computer Networks 26 The Telephone Network (contd) To allow for long-distance calls, switching offices (switches) were connected. Several connections can go through inter- switch trunks simultaneously. At some point, there were too many connections between switching offices!

27 CMPE 150- Introduction to Computer Networks 27 Thus, a second-level hierarchy was added. The current telephone system has at least five levels of hierarchy. The Telephone Network (contd)

28 CMPE 150- Introduction to Computer Networks 28 Addressing Uniquely identifies users. Examples: –Postal address, telephone number. Types of addresses: –Flat. –Hierarchical. –Are postal addresses flat or hierarchical? –And phone numbers?

29 CMPE 150- Introduction to Computer Networks 29 POTS or PSTN For over 100 years, the POTS (Plain Old Telephone System) a.k.a. PSTN (Public Switched Telephone Network) handles voice- band communications. The PSTN is well designed and engineered for the transmission and switching of voice –Real-time. –Low latency. –High reliability. –Moderate fidelity.

30 CMPE 150- Introduction to Computer Networks 30 Evolution of Communications Networks About 30 years ago, a second communications network was created with the goal of providing a better transport mechanism for data. In this class, we will study the technology underpinning data networks.

31 CMPE 150- Introduction to Computer Networks 31 Communication Model Network SourceDestination

32 CMPE 150- Introduction to Computer Networks 32 Simplified Communication Model

33 CMPE 150- Introduction to Computer Networks 33 Components End systems (or hosts), Routers/switches/bridges, and Links (twisted pair, coaxial cable, fiber, radio, etc.).

34 CMPE 150- Introduction to Computer Networks 34 Components (contd) Source –generates data to be transmitted Transmitter –Converts data into transmittable signals Transmission System –Carries data Receiver –Converts received signal into data Destination –Takes incoming data

35 CMPE 150- Introduction to Computer Networks 35 Simplified Data Communications Model

36 CMPE 150- Introduction to Computer Networks 36 Key Tasks Transmission. Signal Generation. Synchronization. Error detection and correction. Addressing and routing End-to-end Recovery. Security.

37 CMPE 150- Introduction to Computer Networks 37 Networking Point to point communication not usually practical –Devices are too far apart. –Large set of devices would need impractical number of connections. Solution is a communications network.

38 CMPE 150- Introduction to Computer Networks 38 Simplified Network Model


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