Overview EE450 Introduction to Computer Networks Professor A Zahid EE450 USC Zahid 1 Course Overview Part Part Part Part Part Part Part Part 1 Data Communications Networking 2 Computer Networking Protocols TCP IP 3 Wide Area Networks WANs 4 Local Area Networks LANs 5 Internetworking 6 Transport Layer Protocols 7 Network Applications 8 Network Security Focus throughout the course is on the public Internet EE450 USC Zahid 2 Growth of Computer Networks Computer Networking has grown explosively Since the 1970s computer communication has changed from a research topic to an essential part of infrastructure Networking is used in every aspect of our lives Business Education Advertising Social Entertainment Production Planning Billing Accounting EE450 USC Zahid 3 Growth of CN Continued In short computer networks are everywhere In 1980 the Internet was a research project that involved a few dozen sites Today the Internet has grown into a huge Network that reaches all of the world The advent and utility of networking has created dramatic economic shifts Network has made telecommuting available to individuals An entire industry emerged that develops networking technologies products and services The importance of computer networks has produced a demand in all industries for people with more networking expertise Companies need professionals to plan acquire install operate and manage the hardware and software systems for networks EE450 USC Zahid 4 Multimedia Convergence Major Industries Video Broadcast TV Film pre recorded on demand e g MPEG Real Net live video phone video teleconference Wireless Computer Software Financial e Commerce etc e mail files Recording executables Broadcast source code Radio data Data Voice Audio html image Network pre recorded on demand streaming or file mp3 live Real Net VoIP Telephone companies Telco Internet Service Providers ISP PDA Computer Hardware Software Telco wireless Hardware Cell phone Pager EE450 USC Zahid 5 Computer Networks A Computer Network is a set of nodes such as routers switches hosts etc interconnected via transmission facilities such as copper cable fiber satellite radio microwave etc for the purpose of providing services to end systems users So why the question mark Non traditional end systems Laptops Cell Phones Tablets gaming Consoles Sensor devices Toasters Refrigerators etc are being connected to the internet Point to point communication is not practical Devices are too far apart Large set of devices would need impractical number of connections See illustration next chart EE450 USC Zahid 6 Generic Computer Network EE450 USC Zahid 7 Example Telephone Network Central Office CO Fully Connected Mesh of FDX links N N 1 2 e g N 6 6 5 2 15 links Total ports N N 1 e g N 6 6 5 30 ports EE450 USC Zahid With Central Office of FDX links N e g N 6 6 links Total of ports N e g N 6 6 ports 8 Clients Servers and Peers A network computer can either provide service or request service A server is a service provider providing access to network resources A Client is a service requester A Peer to Peer network does not have a dedicated server All computers are equal and they both provide and request services EE450 USC Zahid 9 Server Roles Servers can assume several roles and a single server could also have several roles Examples of Servers include File Servers Manages user access to shared files Print Servers Manages user access to print resources Application Servers Similar to FS with some processing Mail Servers Manages electronic messages between users Communications Remote Access Servers Manages data flow and e messages from one network to another Web Servers Runs WWW and FTP servers for access via the Internet Intranet Directory DNS Servers Locates information about networks such as domains EE450 USC Zahid 10 Client Server Model Example World Wide Web Client web browser source Server web server destinationRequest GET index html Http www yahoo com Network html html Response HTML file gif jpeg EE450 USC Zahid html file image file 11 Peer to Peer Model Peer to Peer Each host has both client and server functionalities CPU cycle sharing Example Gnutella KaZaA Skype BitTorrent etc Client Server Request Client Network Response Server Server EE450 USC Zahid 12 Network Applications E mail Voice over IP e g Skype WWW Real time video conferencing Instant messaging Grid computing Remote login On line Social Network P2P file sharing Multi user network games Streaming audio video You Tube Hulu Netflix Facebook Twitter etc E Commerce Distributed Databases Search Note different applications may have different Requirements delay loss Throughput jitter bounds security Number of participants unicast multicast broadcast etc Architecture client server p2p flat hierarchical hybrid etc All applications can communicate over a single shared network EE450 USC Zahid 13 Creating a Networked Application Write programs that run on different end systems communicate over network e g web server software communicates with browser software No need to write software for network core devices application transport network data link physical network core devices do not run user applications applications on end systems allows for rapid application EE450 USC Zahid development application transport network data link physical application transport network data link physical 14 Client Server Architecture Server Always on host Permanent IP address Data centers for scaling Clients Communicate with server May be intermittently connected client server May have dynamic IP addresses Do not communicate directly with each other EE450 USC Zahid 15 P2P Architecture No always on server peer peer arbitrary end systems directly communicate Peers request service from other peers provide service in return to other peers self scalability new peers bring new service capacity as well as new service demands Peers are intermittently connected and change IP addresses e g Gnutella complex management EE450 USC Zahid 16 P2P Centralized Directory EE450 USC Zahid 17 P2P Case Study Skype Architecture Proprietary application layer protocol with encrypted msgs Skype Peers connect to each other for a VoIP call Super Nodes are Skype Peers with special functionality Usernames to IP Address mappings SN Overlay Network Skype Login Server EE450 USC Zahid 18 Cloud Computing EE542 EE450 USC Zahid 19 Cloud Computing Service Models EE450 USC Zahid 20 CDN Content Delivery Networks EE450 USC Zahid 21 Case Study Netflix Architecture