tailieunhanh - Lecture TCP-IP protocol suite (3/e): Chapter 11 - Behrouz Forouzan

Chapter 11 - User data gram protocol. Upon completion you will be able to: Be able to explain process-to-process communication, know the format of a UDP user datagram, be able to calculate a UDP checksum, understand the operation of UDP, know when it is appropriate to use UDP, understand the modules in a UDP package. | Chapter 11 Upon completion you will be able to: User Datagram Protocol Be able to explain process-to-process communication Know the format of a UDP user datagram Be able to calculate a UDP checksum Understand the operation of UDP Know when it is appropriate to use UDP Understand the modules in a UDP package Objectives TCP/IP Protocol Suite Figure Position of UDP in the TCP/IP protocol suite TCP/IP Protocol Suite PROCESS-TO-PROCESS COMMUNICATION Before we examine UDP, we must first understand host-to-host communication and process-to-process communication and the difference between them. The topics discussed in this section include: Port Numbers Socket Addresses TCP/IP Protocol Suite Figure UDP versus IP TCP/IP Protocol Suite Figure Port numbers TCP/IP Protocol Suite Figure IP addresses versus port numbers TCP/IP Protocol Suite Figure ICANN ranges TCP/IP Protocol Suite The well-known port numbers are less than 1024. Note: . | Chapter 11 Upon completion you will be able to: User Datagram Protocol Be able to explain process-to-process communication Know the format of a UDP user datagram Be able to calculate a UDP checksum Understand the operation of UDP Know when it is appropriate to use UDP Understand the modules in a UDP package Objectives TCP/IP Protocol Suite Figure Position of UDP in the TCP/IP protocol suite TCP/IP Protocol Suite PROCESS-TO-PROCESS COMMUNICATION Before we examine UDP, we must first understand host-to-host communication and process-to-process communication and the difference between them. The topics discussed in this section include: Port Numbers Socket Addresses TCP/IP Protocol Suite Figure UDP versus IP TCP/IP Protocol Suite Figure Port numbers TCP/IP Protocol Suite Figure IP addresses versus port numbers TCP/IP Protocol Suite Figure ICANN ranges TCP/IP Protocol Suite The well-known port numbers are less than 1024. Note: TCP/IP Protocol Suite Table Well-known ports used with UDP TCP/IP Protocol Suite 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 TFTP. Note TFTP can use port 69 on either UDP or TCP. Example 1 See Next Slide $ grep tftp /etc/services tftp 69/tcp tftp 69/udp TCP/IP Protocol Suite SNMP uses two port numbers (161 and 162), each for a different purpose, as we will see in Chapter 21. Example 1 (Continued) $ grep snmp /etc/services snmp 161/tcp #Simple Net Mgmt Proto snmp 161/udp #Simple Net Mgmt Proto snmptrap 162/udp #Traps for SNMP TCP/IP Protocol Suite Figure Socket address TCP/IP Protocol Suite USER DATAGRAM UDP packets are called user datagrams and have a fixed-size header of 8 bytes. TCP/IP Protocol Suite Figure .