哈尔滨工业大学：《网络应用开发》英文版 NAD-chapter1new

What's the Internet: nuts and bolts view millions of connected router workstation computing devices: hosts, server end-systems mobile cal Isp pcs worksTaTions, servers PDA's phones, toasters running network apps regional/TSP communication links fiber, copper radio satellite routers: forward packets (chunks) of data thru company network network 哈工大计算机学院李全龙 Netork Application Development 1: Introduction 11

哈工大计算机学院 李全龙 Network Application Development 1: Introduction 11 What’s the Internet: “nuts and bolts” view „ millions of connected computing devices: hosts, end-systems „ pc’s workstations, servers „ PDA’s phones, toasters running network apps „ communication links „ fiber, copper, radio, satellite „ routers: forward packets (chunks) of data thru network local ISP company network regional ISP router workstation server mobile

What's the Internet: nuts and bolts view protocols: control sending router workstation receiving of msgs server mobile e.g., Tcp, Ip, Http, Ftp, PPP cal IsP Internet: " network of networks loosely hierarchical regional/TSP Internet standards RFC: Request for comments IETF: Internet Engineering Task Force company network 哈工大计算机学院李全龙 Netork Application Development 1: Introduction 12

哈工大计算机学院 李全龙 Network Application Development 1: Introduction 12 What’s the Internet: “nuts and bolts” view „ protocols: control sending, receiving of msgs „ e.g., TCP, IP, HTTP, FTP, PPP „ Internet: “network of networks” „ loosely hierarchical „ Internet standards „ RFC: Request for comments „ IETF: Internet Engineering Task Force local ISP company network regional ISP router workstation server mobile

What's a protocol? Used for communications between entities in a system Must speak the same language Entities User applications protocols define format, order e-mail facilities o f msgs sent and received terminals among network entities. and Systems actions taken on msg Computer transmission, receipt Terminal Remote sensor 哈工大计算机学院李全龙 Netork Application Development 1: Introduction 13

哈工大计算机学院 李全龙 Network Application Development 1: Introduction 13 What’s a protocol? „ Used for communications between entities in a system „ Must speak the same language „ Entities „ User applications „ e-mail facilities „ terminals „ Systems „ Computer „ Terminal „ Remote sensor protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

Key elements of a Protocol Syntax Data formats Signal levels Semantics Control information Error handling Timing Speed matching Sequencing 哈工大计算机学院李全龙 Netork Application Development 1: Introduction 14

哈工大计算机学院 李全龙 Network Application Development 1: Introduction 14 Key Elements of a Protocol „ Syntax „ Data formats „ Signal levels „ Semantics „ Control information „ Error handling „ Timing „ Speed matching „ Sequencing

Protocol Functions Encapsulation Segmentation and reassembly Connection contro Ordered delivery Flow control Error control Addressing Multiple×ig a Transmission services 哈工大计算机学院李全龙 Netork Application Development 1: Introduction 15

哈工大计算机学院 李全龙 Network Application Development 1: Introduction 15 Protocol Functions „ Encapsulation „ Segmentation and reassembly „ Connection control „ Ordered delivery „ Flow control „ Error control „ Addressing „ Multiplexing „ Transmission services