Bài giảng TCP/IP - Chapter 23: Simple Network Management Protocol (SNMP)

Chapter 23Simple NetworkManagement Protocol(SNMP)CONTENTS CONCEPT MANAGEMENT COMPONENTS SMI MIB SNMP MESSAGES UDP PORTS SECURITYCONCEPT23.1Figure 23-1ConceptMANAGEMENTCOMPONENTS23.2Figure 23-2Components of network management on the InternetSNMP defines the format of packets exchanged between a manager and an agent. It reads and changes the status (values) of objects (variables) in SNMP packets.SMI defines the general rules for naming objects, defining object types (including range and length), and showing how to encode objects and values. SMI defines neither the number of objects an entity should manage, nor names the objects to be managed nor defines the association between the objects and their values.MIB creates a collection of named objects, their types, and their relationships to each other in an entity to be managed. We can compare the task of network management to the task of writing a program.1. Both tasks need rules. In network  management this is handled by SMI.2. Both tasks need variable declarations.  In network management this is handled  by MIB.3. Both tasks have actions performed by  statements.In network management this is  handled by SNMP.SMI23.3Figure 23-3Object attributesFigure 23-4Object identifierAll objects managed by SNMP are given an object identifier. The object identifier always starts with 1.3.6.1.2.1.Figure 23-5Data typesFigure 23-6Conceptual data typesFigure 23-7Encoding formatFigure 23-8Length formatFigure 23-9Example 1: INTEGER 14Figure 23-10Example 2: OCTET STRING “HI”Figure 23-11Example 3: ObjectIdentifier 1.3.6.1Figure 23-12Example 4: IPAddress 131.21.14.8MIB23.4Figure 23-13mib-2Figure 23-14udp group Figure 23-15udp variables and tables Figure 23-16Indexes for udpTableFigure 23-17Lexicographic orderingSNMP23.5Figure 23-18SNMP PDUsFigure 23-19SNMP PDU formatMESSAGES23.6Figure 23-20SNMPmessage Figure 23-21GetRequestmessageUDPPORTS23.7Figure 23-22Port numbers for SNMP23.8SECURITY