1. Local Area Networks, 3rd Edition David A. Stamper
Part 4: Installation and Management
Chapter 12
LAN Administration: Reactive and Proactive Management

2. Chapter Preview Problem identification and correction System tuning
In this chapter you will study:
Problem identification and correction
System tuning
Capacity planning
Managing system expansion
Network management systems
Network management protocols

3. 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.

4. 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

5. 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

6. 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

7. 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.

8. 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.

9. 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.

10. 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

11. 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.

12. 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.

13. 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.

14. 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

15. 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.

16. 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.

17. 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)

18. 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

19. SNMP Environment Device Being Monitored SNMP Protocol Network
Management
Station
Bridge