Download Local Area Networks, 3rd Edition David A. Stamper

Local Area Networks, 3rd Edition
David A. Stamper
Part 4: Installation and Management
Chapter 12
LAN Administration:
Reactive and Proactive
Management
© 2001 by Prentice Hall
1-1
Chapter Preview
In this chapter you will study:
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Problem identification and correction
System tuning
Capacity planning
Managing system expansion
Network management systems
Network management protocols
© 2001 by Prentice Hall
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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
AUI
Cable connectors
R145
BNC
Cable types
Twisted-pair—UTP,
STP, CAT 3-5
Coaxial cable
Protocols
Ethernet
Token ring
Printer interface
Serial
Parallel
Faults detected
Opens
Shorts
Length
Pair length
mismatch
Near end crosstalk
(NEXT)
Crossed pairs
Terminator
resistance
Category
conformance
Attenuation
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ARCnet
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Protocol Analyzer Functions
Utilization statistics
Number of packets sent by a node
Number of packets received by a node
Packet errors
Data logging
Test packet transmission
Packet filtering
Logging of protocol headers
Logging of data portion of packets
Network load statistics
Alarms
Cable testing
Support for multiple protocols
Printed reports
© 2001 by Prentice Hall
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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.
© 2001 by Prentice Hall
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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.
© 2001 by Prentice Hall
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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.
© 2001 by Prentice Hall
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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
Alerts and alarms
Graphic user interface
Virus protection
Message traffic statistics
Server status monitoring
Workstation status monitoring
Automatic log backup
Meter use of software licenses
Trend analysis
Expert system problem diagnosis
Network topology graphs
User logon statistics
Intruder detection
Media monitoring
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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:
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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
Network
Management
Station
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Device Being
Monitored
SNMP
Protocol
Bridge
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