Introduction Examines a de facto standard for external data representation and presentation as well as a set of library procedures used to perform data conversion Describes the general motivations for using an external data representation and the details of one particular implementation

CONTENTS THE OSI MODEL LAYERS IN THE OSI MODEL TCPIP PROTOCOL SUITE ADDRESSING Tcp/IP VERSIONS CSIE, NTUT, TAIWAN

Multiple Threads Master thread for connection requests Slave threads for handling communication with clients Thread of execution: an abstraction of independent computation Single process can contain one or more threads CSIE, NTUT, Taiwan

Examples Iterative, Connectionless Server (UDP) Iterative, Connected-Oriented Server (TCP) Concurrent. Connection-Oriented Server(TCP)

Conceptual Server Algorithm Simple Server Algorithm Create a socket Bind the socket to the port Enter an infinite loop Accept request Process request Reply request Not enough in practice generally

Introduction Single thread for multiple transport protocols Motivation Server design and process structure An iterative example Concurrent multiprotocol servers

How applications become clients by initiating communication How applications use TCP or UDP protocols to contact a server How they use socket calls to interact with the protocols CSIE, NTUT, Taiwan

Introduction Loosely specified protocol software interface Interface functionality Conceptual interface specification · System calls Two basic approaches to network communication Basic I/ functions in Linux

CONTENTS TCP SERVICES NUMBERING BYTES FLOW CONTROL SILLY WINDOW SYNDROME ERROR CONTROL TCP TIMERS CONGESTION CONTROL SEGMENT OPTIONS CHECKSUM

Transport layer protocol is to reate a process-to-process communication Provide control mechanisms Provide a connection mechanism for the processes