The transport layer is responsible for process-to-process delivery—the delivery of a packet, part of a message, from one process to another. Two processes communicate in a client/server relationship, as we will see later. | Chapter 23 Process-to-Process Delivery: UDP, TCP, and SCTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 23. 23-1 PROCESS-TO-PROCESS DELIVERY The transport layer is responsible for process-to-process delivery—the delivery of a packet, part of a message, from one process to another. Two processes communicate in a client/server relationship, as we will see later. Client/Server Paradigm Multiplexing and Demultiplexing Connectionless Versus Connection-Oriented Service Reliable Versus Unreliable Three Protocols Topics discussed in this section: 23. The transport layer is responsible for process-to-process delivery. Note 23. Figure Types of data deliveries 23. Figure Port numbers 23. Figure IP addresses versus port numbers 23. Figure IANA ranges 23. Figure Socket address 23. Figure Multiplexing and demultiplexing 23. Figure Error control 23. Figure Position of UDP, | Chapter 23 Process-to-Process Delivery: UDP, TCP, and SCTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 23. 23-1 PROCESS-TO-PROCESS DELIVERY The transport layer is responsible for process-to-process delivery—the delivery of a packet, part of a message, from one process to another. Two processes communicate in a client/server relationship, as we will see later. Client/Server Paradigm Multiplexing and Demultiplexing Connectionless Versus Connection-Oriented Service Reliable Versus Unreliable Three Protocols Topics discussed in this section: 23. The transport layer is responsible for process-to-process delivery. Note 23. Figure Types of data deliveries 23. Figure Port numbers 23. Figure IP addresses versus port numbers 23. Figure IANA ranges 23. Figure Socket address 23. Figure Multiplexing and demultiplexing 23. Figure Error control 23. Figure Position of UDP, TCP, and SCTP in TCP/IP suite 23. 23-2 USER DATAGRAM PROTOCOL (UDP) The User Datagram Protocol (UDP) is called a connectionless, unreliable transport protocol. It does not add anything to the services of IP except to provide process-to-process communication instead of host-to-host communication. Well-Known Ports for UDP User Datagram Checksum UDP Operation Use of UDP Topics discussed in this section: 23. Table Well-known ports used with UDP 23. In UNIX, the well-known ports are stored in a file called /etc/services. Each line in this file gives the name of the server and the well-known port number. We can use the grep utility to extract the line corresponding to the desired application. The following shows the port for FTP. Note that FTP can use port 21 with either UDP or TCP. Example 23. Example (continued) SNMP uses two port numbers (161 and 162), each for a different purpose, as we will see in Chapter 28. 23. Figure User datagram format .
