1-1© 2001 by Prentice Hall

Local Area Networks, 3rd EditionDavid A. Stamper

Part 4: Installation and Management

Chapter 12

LAN Administration: Reactive and Proactive

Management

1-2© 2001 by Prentice Hall

Chapter Preview

• Problem identification and correction

• System tuning

• Capacity planning

• Managing system expansion

• Network management systems

• Network management protocols

In this chapter you will study:

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Reactive Network Management

• Information gathering– Any failure experienced by a user can be the result of user errors, software errors, hardware

errors, inappropriate environment settings, or faulty security. The first step in problem resolution, information gathering, involves the identification of various possible causes of the failure.

• Diagnosis and Analysis– The objective of problem diagnosis and analysis is to isolate the source of the problem. This

leads to problem identification and solution.

• Identification and Resolution– Once the LAN administrator has correctly identified the problem, it must be corrected. The

problem dictates the solution.

• Documentation– Sometime one problem occurs several times. Having good documentation of previous

problems and their solutions can significantly reduce the time it takes to correct a problem that appears again.

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Features of Remote Control Software

Remote screen display

Remote keyboard entry

Ability for many viewers to be connected to on node

Ability of one viewer to view multiple nodes

Password protection

Audio tone to indicate when someone begins viewing

File transfer

Ability to discover and report the host configuration

Ability to print a memory map of a host

Chat mode, allowing users at both ends to exchange messages over the connection

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Cable Tester Functions

Cable connectors

Cable types

Protocols

Printer interface

Faults detected

R145

Twisted-pair—UTP, STP, CAT 3-5

Ethernet

Serial

Opens

Pair length mismatch

Terminator resistance

BNC

Coaxial cable

Token ring

Parallel

Shorts

Near end crosstalk (NEXT)

Category conformance

AUI

ARCnet

Length

Crossed pairs

Attenuation

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Protocol Analyzer Functions

Utilization statistics

Number of packets received by a node

Data logging

Packet filtering

Logging of data portion of packets

Alarms

Support for multiple protocols

Number of packets sent by a node

Packet errors

Test packet transmission

Logging of protocol headers

Network load statistics

Cable testing

Printed reports

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Proactive Network Management

• Ideally, the network administrator anticipates problems and corrects them before they occur. This type of administration is called proactive network management. This is not always possible because an administrator cannot usually anticipate hardware and software failures.

• A good LAN administrator notices small changes in performance of the system and takes steps to avoid their becoming major problems for LAN users.

• Another LAN-administration task is capacity planning, which basically is planning for the future.

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Tuning a System

• One of the primary tools used to tune a network is a network management system (NMS). A good NMS has both data collection and analysis components and creates monitors that raise alarms if performance degenerates below certain levels.

• Another tool used in tuning is a network analyzer. The network analyzer reports on the type and number of packets being sent, the number of transmission errors encountered, and so on.

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Tuning a System (cont.)

• The general process of tuning is outlined as follows:– 1. Measure system performance; collect and analyze data.– 2. Identify possible solutions to problems.– 3. Choose one solution that has the highest merit; the best gain in

efficiency and returned performance per cost of implementation, or the quickest and easiest to implement.

– 4. Install and test the selected solution.– 5. Evaluate the results.– 6. If performance is still poor, go back to step 1.– 7. Implement and document the solution.

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Capacity Planning

• Capacity planning is a key responsibility of the network administrator. Capacity planning is the art of anticipating the workload of the network months or years in advance and taking steps to ensure that the network is able to withstand future loads.

• Among the many tools that have been developed for capacity planning on microcomputers, three are particularly effective:

– performance monitors– simulation models– workload generators

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Simulation Models

• Simulation models allow the user to describe network hardware configurations and application activities. The model analyzes how the system can be expected to perform under the described conditions. This is useful for estimating response times, processor use, line congestion, and potential bottlenecks.

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Workload Generators

• Whereas the simulation model estimates system use and can be run on a single microcomputer, a workload generator actually generates transaction loads for execution on the proposed configuration. A workload generator together with a performance monitor can illustrate how the system will actually function in the proposed configuration.

• A workload generator requires that you build the network to test it out. It is therefore used more often when acquiring a new LAN.

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Configuration of Hardware and Software Upgrades

• Installing hardware and software upgrades affects existing LAN users, whereas initial LAN installation is not impeded by the needs of existing users. LAN administrators must plan upgrades carefully to minimize the disruption to LAN users.

• Ideally, the administrator can first install and test all hardware and software upgrades on an experimental LAN, that is, a small LAN separate from the production LAN. Many installations do not have the luxury of an experimental LAN and make all changes directly to the operational system.

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Network Management System Functions

Event logging

Graphic user interface

Message traffic statistics

Workstation status monitoring

Meter use of software licenses

Expert system problem diagnosis

User logon statistics

Media monitoring

Alerts and alarms

Virus protection

Server status monitoring

Automatic log backup

Trend analysis

Network topology graphs

Intruder detection

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Network Management Systems

• Monitors, or agents, located throughout the network, can be dedicated hardware or software devices, or they can be intelligent network devices such as bridges, hubs, or intelligent microcomputer device controllers.

• Network management software collects data from the monitors. The data is usually stored in a database for later analysis.

• The filter receives warning messages, reformats them, forwards the messages to one or more control centers, and suppresses redundant messages.

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Network Management Systems (cont.)

• An alarm can be an audio signal, a flashing light, a call to a pager, a FAX message, or a message to a remote system. An alert is less obvious than an alarm. An alert may indicate potential problems by using colors on a color monitor.

• The report generator allows network administrators to analyze data that has been captured in the network database.

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Simple Network Management Protocol

• The simple network management protocol (SNMP) is based on the transmission control protocol/internet protocol (TCP/IP)

• SNMP has four key components:– the protocol itself– structure of management information (SMI)– management information base (MIB)– network management system (NMS)

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Common Management Information Protocol

• In competition with SNMP is the International Standards Organization’s (ISOs) common management information protocol (CMIP).

• CMIP has a more complex protocol for exchanging messages among network components and has a richer command language and management information base. Therefore, CMIP has the potential for better control and the ability to overcome the limitations of SNMP.

• There are currently no provisions for interoperability of SNMP and CMIP, and it will take some time for CMIP to overcome the impetus of SNMP

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SNMP Environment

NetworkManagement

Station

Device BeingMonitored

SNMPProtocol

Bridge