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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:
1-3© 2001 by Prentice Hall
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.
1-4© 2001 by Prentice Hall
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
1-5© 2001 by Prentice Hall
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
1-6© 2001 by Prentice Hall
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
1-7© 2001 by Prentice Hall
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.
1-8© 2001 by Prentice Hall
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.
1-9© 2001 by Prentice Hall
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.
1-10© 2001 by Prentice Hall
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
1-11© 2001 by Prentice Hall
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.
1-12© 2001 by Prentice Hall
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.
1-13© 2001 by Prentice Hall
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.
1-14© 2001 by Prentice Hall
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
1-15© 2001 by Prentice Hall
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.
1-16© 2001 by Prentice Hall
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.
1-17© 2001 by Prentice Hall
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)
1-18© 2001 by Prentice Hall
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
1-19© 2001 by Prentice Hall
SNMP Environment
NetworkManagement
Station
Device BeingMonitored
SNMPProtocol
Bridge
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