Guide to TCP/IP, Third Edition. Chapter 11: Monitoring and Managing IP Networks

Transcription

1 Guide to TCP/IP, Third Edition Chapter 11: Monitoring and Managing IP Networks

2 Objectives Understand the basic principles and practices involved in managing modern networks Explain the role that the SNMP can play on an IPbased network, and understand its basic structure and function Understand how to install, configure, and use SNMP consoles, tools, and utilities Monitoring and Managing IP Networks 2

3 Objectives (continued) Deploy tools and utilities to maintain an SNMP network management system Explain the issues involved in integrating SNMPbased network management tools with other network management environments Understand common SNMP errors and how to troubleshoot them Monitoring and Managing IP Networks 3

4 Understanding Network Management Practices and Principles Tasks involved in managing a network Depend on the ability to collect data about a network and detect network-related occurrences End stations Usually known as managed devices Any kind of system where management-related software is installed and running Management entities Usually function within the context of a network management system (NMS) Monitoring and Managing IP Networks 4

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6 The OSI Network Management Model OSI network management model incorporates the following five layers Accounting management Configuration management Fault management Performance management Security management Monitoring and Managing IP Networks 6

7 Practical Network Management OSI network management model Does an excellent job of categorizing and cataloging tasks and activities Make systematic network management a priority Obtain right mix of software components and tools that can be used as part of a program of Regular, scheduled network maintenance and care Monitoring and Managing IP Networks 7

8 In-band Versus Out-of-band In-band management Management Traffic travels along the regular network data path. Out-of-band management Traffic alerts travel on a separate non-data path Solution supports communications between management agents and the manager device Monitoring and Managing IP Networks 8

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11 Understanding SNMP Request/response-based protocol used to Transport management messages between an SNMP agent and an SNMP manager SNMP version 1 (SNMPv1) Uses plain text passwords SNMP version 2 (SNMPv2) Includes two improvements: protocol enhancements and security enhancements SNMP version 3 (SNMPv3) Addresses shortcomings of previous versions Monitoring and Managing IP Networks 11

12 Understanding SNMP (continued) SNMPv1 consists of the following basic elements: Management Information Base objects SNMP agents SNMP managers SNMP messages Monitoring and Managing IP Networks 12

13 Management Information Base Objects Management Information Base (MIB) Database of manageable objects for a device Structure of Management Information (SMI) Defines object formats in any MIB using a particular form of notation called Abstract Syntax Notation One (ASN.1) ASN.1 Language used to describe a type of object and the object identifier (OID) Monitoring and Managing IP Networks 13

14 OID Management Information Base Objects (continued) Sequence of non-negative integers that traverses an object tree Subordinates Branches of the object tree In SNMP Object is identified by the path used to get to a specific device identifier on an object tree Monitoring and Managing IP Networks 14

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19 Remote Monitoring Used to monitor and administer remote segments of a distributed network Places agents, called network probes, at various locations on the distributed network Probes Standalone devices that contain a NIC, a processor, memory, and software Monitoring and Managing IP Networks 19

20 ROM Ethernet First version of RMON Ethernet based Has nine distinct groups of objects Ethernet statistics, History control Alarm, Host HostTopN, Matrix Filter, Packet capture Event Monitoring and Managing IP Networks 20

21 SNMP Agents SNMP agent software Placed on devices that can be managed by SNMP managers SNMP agents Answer to SNMP manager s queries for information about the objects in agent s MIB SNMP managers Query SNMP agents for the information maintained about MIB objects Monitoring and Managing IP Networks 21

22 SNMP Messages SNMP managers and agents communicate over UDP with a specific set of commands GET-REQUEST GET-RESPONSE GET-NEXT SET TRAP Monitoring and Managing IP Networks 22

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24 SNMP Security SNMPv1 Offers only a simple password system, and cannot be considered truly secure Basic community names Read-Only (or Monitor) community name Read/Write (or Control) community name Alert (or Trap) community name Monitoring and Managing IP Networks 24

25 Installing and Configuring SNMP Agents and Consoles Installing a network management console is more complex than installing agent software Many proprietary consoles that differ greatly from one another Console configuration also is fairly complex For many packages, completing an initial configuration may take six months or longer Configuration is never truly finished Typically require dedicated resources and constant maintenance Monitoring and Managing IP Networks 25

26 SNMP Consoles, Tools, Utilities, and Key Files Lion s share of market belongs to three products HP OpenView s Network Node Manager (NNM) Advanced Edition IBM s Tivoli NetView Computer Associates Unicenter Monitoring and Managing IP Networks 26

27 Integrating SNMP with Other Management Environments Common modules PING Database change control modules Dynamic topological maps Inventory modules Service-level tracking To effectively use data gathered via SNMP Other managed environments usually have reporting capabilities Monitoring and Managing IP Networks 27

28 Troubleshooting SNMP Community names Must match on both the SNMP agent and the network management station Case sensitive Three levels of community strings Read-Only (Monitor) Read/Write (Control) Alert (Trap) Monitoring and Managing IP Networks 28

29 Summary Network management Involves placing specific software components, called management agents, into managed devices Network management systems rely on two kinds of activities to perform management tasks The ability of managed devices to issue alerts when specific events occur The ability of management entities to poll managed devices regularly Monitoring and Managing IP Networks 29

30 Summary (continued) Most NMSs Provide various methods for out-of-band management Discipline of network management Described in the OSI network management model For IP-based networks SNMP carries management-related messages and data among network management agents and entities Monitoring and Managing IP Networks 30

31 Summary (continued) SNMP s management data Resides in a database of manageable objects called a Management Information Base Order is important When loading MIBs into a management station Remote Monitoring MIB Used to monitor and manage remote segments on a distributed network Monitoring and Managing IP Networks 31

32 Summary (continued) SNMP messages Use UDP for transport and IP for network access Ensuring SNMP security requires Changing default community names Managing the transit of SNMP messages across organizational network Boundaries Troubleshooting SNMP requires Good working knowledge of local network conditions Monitoring and Managing IP Networks 32