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Technologies for EC/EB Walt Scacchi FEMBA 290 Winter 2003 1 Chapter 2 Internet Infrastructure Copyright (C) 2003, Addison-Wesley Figure 2.1 This chapter introduces the technology foundation for EC/EB. Applications The World Wide Web The Internet The global data communication network Figure 2.2 Communication requires five elements. Transmitter Medium Receiver Message Protocol: a set of rules for transmitting a message. Message Information/content Transmitter Source or sender Medium Path or pipe Receiver Sink or destination Figure 2.6 Bandwidth. Amount of data a medium can transmit in a given time. Conventions B – bytes b – bits K – 1,000 M – 1,000,000 G – 1,000,000,000 T -- 1,000G P -- 1,000T Connection Type Bandwidth Local telephone line 56 Kbps Wireless 2G digital cellular 2.5G digital cellular 3G digital cellular Bluetooth Wi-Fi (802.11b) 19.2 Kbps 144 Kbps 2 Mbps 1 Mbps Up to 11 Mbps Home satellite service 400 Kbps DSL 1.44 Mbps Cable service 2 to 10 Mbps Leased line (T-1, T-3) 1.5 to 43 Mbps Fiber optic cable Up to 10 Gbps Networks Network: two or more computers or devices linked by communication lines. Each computer/device is a node Transmitter and receiver are nodes The network is the medium Communication rules are defined by a protocol Protocols Communication protocol An agreed-upon format or procedure for transmitting data. Implemented in software Key issues Deliver message reliably (TCP) or without delay (e.g., UDP, RTSP) Detect and correct message transmission errors (TCP yes, UDP no) Figure 2.7 An electronic message consists of a header, a body, and a trailer. Message Header The header carries delivery information Body Information about the message The trailer is often optional. Trailer Message Delivery Broadcast Point-to-point (Narrowcast) Every message sent to every node Node picks out messages addressed to it Bus and some star networks Message moves node-to-node Topology or routing determines path Peer-to-Peer (e.g, Instant messaging) Direct point-to-point connection Figure 2.17 A message’s packets can follow different paths. Router 1 Router 6 Router 8 Router 3 Router 4 Router 4 Router 2 Router 5 Router 5 Router 5 Router 7 Router 9 Figure 2.11 Internetworking. Process of linking two or more networks. Workstation Workstation Workstation Workstation Workstation Workstation Server Bridge Server A bridge links similar networks Workstation A gateway links dissimilar networks Workstation Server Gateway Workstation Workstation Figure 2.12 A client/server network. Client Client Server Server Printer Controls access (view) to served resources Software (e.g., Apache Web Server) Hardware also called server Client Client Requests resources from server (on demand) Software (e.g., Mozilla Web Browser) Hardware is PC/workstation File system Client The Backbone Network Service Provider (NSP) Network Access Point (NAP) National wide-area network (e.g., WorldCom) Lease bandwidth to Internet Service Providers (ISPs) Place where NSPs meet and exchange data Regional ISP Statewide of regional backbones Figure 2.18 The TCP/IP model. Application layer The top two layers work with the message. Transport layer Internet layer The bottom two layers work with packets and control the network. Network access layer Figure 2.20 The application layer protocols support application programs. From application program Application layer FTP telnet http SMTP POP SNMP Other DNS Transport layer Internet layer Network access layer To transport layer Open standards TCP/IP is an example Promotes Platform independence Interoperability Open standards make the Internet a true public medium. Figure 2.28 A domain name consists of two to four words separated by dots. sbaserver1.sba.muohio.edu Top-level domain Miami University domain SBA sub-domain Server within SBA sub-domain Domain: a set of nodes administered as a unit. Figure 2.31 A domain name and an IP address convey the same information. sbaserver1.sba.muohio.edu 134.53.40.2 Physical transmission requires IP address Domain name system converts domain name to equivalent IP address Figure 2.35 The e-commerce infrastructure. Web application E-commerce application World Wide Web Internet Data communication network