Chapter 12

LAN Administration: Reactive and Proactive Management

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Reactive Network Management

Unfortunately most network management is reactive.  This means that you as an administrator react to a problem and solve it.  For example if users can not receive e-mail you would fix that problem.  But what steps do you take to fix it?  There are logical step used to identify the problem and resolve it.

  • Information gathering: Gather as much information about the problem as you can.  What kind of computer are they on?  What was running when the error occurred?  What has changed since it has worked?  Does it work on a computer near by?  What is the severity of the problem?  What priority is the problem.

  • Diagnosis and analysis: Take the data you gather and analyze it.  Is it a localized problem or is it affecting multiple users?  Is it user error or hardware/software error?

    • In this section we talk about remote control software.  Once you have gathered as much information from the user as you can, you will want to look at the computer itself and see what else you can find.  Since you may be managing a large network with multiple sites it might prove to be useful to see the users desktop on your screen.  There are many software packages for remote controlling some with more features then others.  Below is a list of a few of them

  • Problem identification: Use the information you gathered in the previous steps to determine what the problem is.  As you gain experience in the field this will become easier because you will have past experiences to rely on.  As a new tech you shouldn't be afraid to ask questions.  It is better to ask a question of a more senior tech and solve the problem quickly then it would be to try and figure it out on your own.

  • Problem resolution: Once you have identified the problem you will take the appropriate steps to fix what is causing the problem.  In this step you want to be careful not to chase symptoms and actually fix the problem.  For example if the problem was a damaged file and you restore it from tape you have fixed the symptom of a larger problem.  You might want to take the time and figure out how it became damaged in the first place.  Once you have fixed the problem you will want to let the user know and verify that it is working.  If not you will want to go back to Problem Identification.

  • Documentation: If you solved the problem document what you did to fix it and what the symptoms were.  This way if the problem happens in the future you will be able to identify it easily.

Proactive Network Management

Proactive management is solving problems before they happen.  You should know how the network is supposed to perform and notice when there is a slow down.  Also you may realize you are running low on network ports so you would do an upgrade to add more ports.  Unfortunately proactive management can be difficult since you spend a lot of time with reactive management and it is hard to predict failures.

System tuning and capacity planning

Network Associates Sniffer

(View there website)

Part of proactive management is using tools to analyze your network and looking for trends.  A NMS (Network Management System) can be used to monitor certain aspects of a network and server hardware.  We will talk more about NMS's in the next section.  Another tool that can be used is a network analyzer to analyze packets on your network.  This can help to determine what kind of data is being sent and if network load increases.  Also they will help you find computers using protocols that aren't needed.  For example if you recently removed an old Novell server that was using IPX/SPX as its protocol and the new server uses TCP/IP you can locate all clients that are still using IPX/SPX.  Once you find them you can remove the protocols and eliminate unneeded traffic.  If you are interested in playing with a network analyzer you can download a copy of Ethereal.  This is a free program for Windows, Mac (OS X), Linux.

Capacity Planning is planning ahead to add network drops and improve network throughput.  Sometimes it is obvious that you need to add drops to the network, for example when new offices will be added, etc.  But the need to improve your network is not as easy to identify.  As you use the tools mentioned in this chapter you might find the the speed of the network has decreased.  This might be because people are utilizing more network applications then when the network was installed.  In this case you might decide to upgrade to 100Mbps or even 1000Mpbs.  You also might decide to replace some copper runs with fiber runs.  In any case you will want to run tests on your network at different times to establish data showing the speed of the network then after the upgrade you will run the same tests to verify that the networks speed has increased.

You can use Simulation Models to setup the network logically in a computer model and run tests on it to see if a proposed upgrade will produce the desired results.  In the Simulation model you would use a Workload Generator to generate simulated work in the model.

Hardware and Software Acquisition

  • Site Planning and Preparation: Once you have decided what hardware you are going to purchase you will want to make sure the it will work in your site.  You might have to install power lines or maybe data lines.

  • Configuration or Hardware and Software Upgrades: If possible test all upgrades in a test network.  When you have determined everything will work you will want to do the upgrades at a time when it will interfere with the end user the least.  For example, you might want to install a new server on the weekend when the network isn't in use.

  • Upgrade Configuration Steps: This can be broken down into four steps.

    • Installation: One the ordered equipment comes in you will want to physically hook it up or install it if it is software.  If this is going to affect used you will want to schedule this work.

    • Testing: You will then test the new software and verify that it works and that security is setup properly.

    • Training: Next you would train users how to use the upgraded software so when it is put in place they will have no problem using it.

    • Making Changes Operational: Finally you roll over to the new system and monitor it to verify it is working.  You might find you need to do some tweaking at this point.

  • Planning Software Upgrades: This can be broken down into three steps.

    • User Transition: You will be changing the way the user interfaces with there application.  You will want to make sure they are trained on the new system. 

    • File Compatibility: You will want to make sure the new and old systems can read each others files and that data will not be lost in the upgrade

    • Reliability: You will want to make sure the system is reliable. 

Network Management Systems and Network Management Protocols

A good NMS has both data collection and analysis components and creates that sound alarms if performance drops below a predefined level.  Devices such as switches and router can be setup to interact with the NMS through common protocols.  A router may report back to the NMS that a T1 line is down and in turn that might trigger an e-mail or page to the person(s) responsible for the T1 line.  To the right is a picture of a very simple NMS type system that is built into Windows NT/2k/XP/2003.  This will allow you to monitor hardware and system state as well as trigger alerts.

The protocols that network devices would use to report to the NMS are SNMP (Simple Network Management Protocol) and CMIP (Common Management Information Protocol)

SNMP is an application layer protocol which is part of the TCP/IP protocols and has four key components:

Performance Monitor in Windows 2003 Server

  • The protocol itself

  • SMI: Structure of management information - Defines how all information will be displayed in the MIB

  • MIB: Management information base - This is the database that defines the hardware and software elements to be monitored.

  • NMS: Network management system - The user interface for the data collected from the hardware and software.

CMIP is a protocol in direct competition with SNMP that supports a richer command structure and has the potential for better control.  This protocol came out later then SNMP and hasn't been adopted as widely.

More Information


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