A baseline defines the typical activity of your network. Keeping a baseline document of activity on a segment lets you determine when the activity is atypical. Atypical activity might be caused by a problem or network growth. To create a baseline activity, you should gather statistical information when the network is functioning typically.
The following sections provide information about creating and using a baseline:
For segment statistics such as bandwidth utilization, you should create a trend graph that plots information over a period of time. Statistics sampling that gathers data over a short period of time can be misleading. If you have added one or more network components, it is useful to create another baseline against which you can compare future activity.
You can export the data you gather in Novell ZENworks Server Management into programs, such as spreadsheets, for further analysis and to maintain records over time.
You can use the baseline document for the following purposes:
Novell ZENworks Server Management lets you set alarm thresholds for statistics on segments monitored by the network monitoring agent software, so that if the threshold is exceeded, you are notified at Novell ConsoleOne. Setting alarm threshold values for statistics on a segment eliminates the need for you to constantly monitor segments for problems.
Novell ZENworks Server Management provides default values for thresholds of various alarms on Ethernet, FDDI, and token ring segments. Refer to the table in Configuring Alarm Options from the Set Alarm Dialog Box for a list of alarm statistics tracked by Novell ZENworks Server Management. By creating a baseline of activity on the segment, you can determine whether the default values are appropriate for segments in your network. For example, after tracking segment utilization, you would set an alarm threshold for bandwidth utilization at about 5% to 10% higher than typical utilization. You are then alerted if utilization is greater than usual for that segment.
IMPORTANT: If you want to use this alarm notification feature, you must enable segment alarms.
By comparing current network performance against the performance recorded in your baseline document, you can determine how performance is affected by network changes. This comparison also helps you plan for network growth and justify network upgrades and expansion. You can view graphs of real-time trends for various Ethernet, FDDI, and token ring statistics. If an RMON2 agent is installed on a segment, you can also view historical trends for those statistics over hourly, daily, weekly, monthly, and yearly periods. Refer to Analyzing Trend Data for a Segment for details about how to view a trend of segment performance. Refer to the table in Choosing Options to Display Stations on a Segment for a list of statistics based on which you can display a trend of segment performance.
You should include the following key characteristics in each network baseline document:
The bandwidth utilization statistic indicates the percentage of network bandwidth used. Bandwidth utilization is likely to be higher at certain times during the day (for example, when users log in to the network in the morning), week, or month. Tracking bandwidth utilization helps you balance traffic loads among network segments, servers, and routers for a more efficient network. This information also helps you determine the effect of network growth on performance. As new workstations and applications are added to a network, bandwidth utilization typically increases.
Monitoring the number of packets on the wire provides information about the traffic on the segment. By looking at the change in the packets per second after a user launches a new application, you can calculate what the increase in packets per second will be when all the users you expect to use the application start using it. Packets per second differs from utilization. Utilization is based on the number of kilobytes on the segment per second, but packets can range in size. Therefore, utilization can increase as a result of an increase in the size or number of packets. If the number of packets increases but utilization does not, it is likely that the number of small packets increased but the increase did not affect utilization.
By including error rates in your baseline, you can determine when error rates on the network are atypical. This is important because network errors can bring down the network. A higher error rate can result from a hardware problem or network growth. If errors increase but utilization does not, there might be a problem with a component, for example a faulty network board or transceiver.
Tracking kilobytes per second lets you determine the throughput of your network. From this information, you can determine the percentage of the total possible bandwidth that is in use. For Ethernet networks, the maximum possible utilization is 10 Mbps. For token ring networks, the maximum possible utilization is 4 or 16 Mbps (depending on the hardware).
Keeping track of the top three servers on the network helps you distribute the load among them as you add new users and applications. See Viewing Statistics of the Top 20 Nodes for details about how to display a list of top nodes on a monitored segment. You should also monitor the number of Request Being Processed packets. A constantly increasing number of these packets indicates a server overload condition. You can monitor these packets by doing a packet capture and decode. See Capturing Packets and Displaying Captured Packets for details about how to capture and display decoded packets.
With the Segment Trends view, you can view many segment statistics and export that data into another application (such as a spreadsheet) for later analysis. The data is saved as a text file that stores statistical values of the trend you display. To export the trend data to a file, click the Export button in the toolbar of the Segment Trends view. For details, see Analyzing Trend Data for a Segment.
You can view current utilization for a segment through the Segment Dashboard view. To access this view, select a segment, click View > click Segment Dashboard. For details, see Determining the Performance of Individual Segments.