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

Guide to TCP/IP, Third Edition

Chapter 11: Monitoring and Managing IP

Networks

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 IP-based network, and understand its basic structure and function

• Understand how to install, configure, and use SNMP consoles, tools, and utilities

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Objectives (continued)

• Deploy tools and utilities to maintain an SNMP network management system

• Explain the issues involved in integrating SNMP-based network management tools with other network management environments

• Understand common SNMP errors and how to troubleshoot them

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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)

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The OSI Network Management Model

• OSI network management model incorporates the following five layers– Accounting management– Configuration management– Fault management– Performance management– Security management

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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

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In-band Versus Out-of-band Management

• In-band 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

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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

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Understanding SNMP (continued)

• SNMPv1 consists of the following basic elements:– Management Information Base objects– SNMP agents– SNMP managers– SNMP messages

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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)

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Management Information Base Objects (continued)

• OID– 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

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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

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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

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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

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SNMP Messages

• SNMP managers and agents communicate over UDP with a specific set of commands– GET-REQUEST– GET-RESPONSE– GET-NEXT– SET– TRAP

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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

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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

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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

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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

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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)

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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

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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

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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

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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