1. Basic Concepts of Internet Technology What is a computer network? Isolated computers vs. networked computers internetworking The Internet What’s a protocol?

2. What is a computer network? An interconnected collection of computers Examples of networks: –Telephone networks –Satellite networks –Mobile telephone networks –Cable TV networks –Intranets and extranets –Internet Computer networks vs. other types networks (general, different types of data vs particular application)

3. Basic Concepts: Isolated Machines Independent Workstations (Local Processing) How to share data?

4. Basic Concepts: Networked Machines Computer Network Workstations (Local Processing) File Servers Application Servers Client-Server Model

5. Classifications of Computer Networks Based on size: –System/Storage area networks (SAN) within the same room connecting processors to storage servers. –Local area networks (LAN) in a close proximity –Metropolitan area networks (MAN) span a city –Wide area networks (WAN) connecting computers situated anywhere Connects many networks together

6. internetwork A collection of networks

7. The Internet Topology See http://www.cybergeography.org/atlas/topology.html for more Internet topologies.

8. What’s the Internet: a service view communication infrastructure: enables distributed applications: –WWW, email, games, e- commerce, database., cyberspace

9. What’s the Internet: “nuts and bolts” view millions of connected computing devices: hosts, end-systems –pc’s workstations, servers –PDA’s communication links –fiber, copper, radio, satellite routers: forward packets (chunks) of data across networks local ISP company network regional ISP router workstation server mobile

10. What’s the Internet: “nuts and bolts” view protocols: control sending, receiving of msgs –e.g., TCP, IP, HTTP, FTP Internet: “network of networks” –public Internet versus private intranet –collection(s) of SAN, LAN, MAN, WAN local ISP company network regional ISP router workstation server mobile

11. What’s a protocol? a human protocol and a computer network protocol: Hi Got the time? 2:00 TCP connection req. TCP connection reply. Get http://gaia.cs.umass.edu/index.htm time

12. What’s a protocol? human protocols: “what’s the time?” “I have a question” introductions … specific messages sent … specific actions taken when messages received, or other events network protocols: machines rather than humans all communication activity in Internet governed by network protocols protocols define format, order of messages sent and received among network entities, and actions taken on message transmission, receipt