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

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

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.

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

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

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

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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)

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

SNMP Environment Device Being Monitored SNMP Protocol Network Management Station Bridge