聊城大学计算机学院计算机操作系统（1）英文课件 Chapter13.ppt

Networking Chapter 12 Distributed Capabilities Communications architectures Software that supports a group of networked computers Network operating system Each computer has its own private operating system Distributed operating system Common operating system shared by a network of computers The Need for a Protocol Architecture Computer communications Exchange of information between computers for the purpose of cooperative action Computer network When tow or more computers are interconnected via a communication network Two Concepts Protocol Used for communication between entities in different systems Protocol architecture Broken into subtasks, each of which is implemented separately File Transfer The TCP/IP Protocol Architecture Protocol suite Five relatively independent layers Physical Network access Internet Host-to-host, or transport Application Physical Layer Specifying the characteristics of the transmission medium Nature of the signals Data rate Network Access Layer Concerned with the exchange of data between an end system and the network Different standards Circuit switching Packet switching (frame relay) LANs (Ethernet) Internet Layer Procedures for data to traverse different networks Implemented in the end systems and routers Transport Layer Ensures all data arrives at the destination and in the order sent TCP Application Layer Supports various user application Example: file transfer TCP Header UDP IP IPv6 Provides enhancements over existing IP Designed to accommodate higher speeds of a mix of data streams, graphic and video Provides more addresses Includes 128-bits for addresses IP uses 32-bit address IPv6 TCP/IP Concepts Protocols and Headers Items in the Header Destination network address Facilities requests Example: priority TCP.IP Applications Simple Mail Transfer Protocol (SMTP) File Transfer Protocol TELNET Sockets Enable communication between a client and server Concatenation of a port value and an IP address form a socket Two Types of Sockets Strea