Establishing The Network Performance Baseline


Establishing a network performance baseline requires collecting key performance data from the ports and devices that are essential to network operation. This information helps to determine the "personality" of the network and provides answers to the following questions:
How does the network perform during a normal or average day?
Where are the underutilized and over-utilized areas?
Where are the most errors occurring?
What thresholds should be set for the devices that need to be monitored?
Can the network deliver the identified policies?
Measuring the initial performance and availability of critical network devices and links allows a network administrator to determine the difference between abnormal behavior and proper network performance as the network grows or traffic patterns change. The baseline also provides insight into whether the current network design can deliver the required policies. Without a baseline, no standard exists to measure the optimum nature of network traffic and congestion levels.
In addition, analysis after an initial baseline tends to reveal hidden problems. The collected data reveals the true nature of congestion or potential congestion in a network. It may also reveal areas in the network that are underutilized and quite often can lead to network redesign efforts based on quality and capacity observations.

Steps For Establishing a Network Baseline:

Planning for the First Basline
Because the initial network performance baseline sets the stage for measuring the effects of network changes and subsequent troubleshooting efforts, it is important to plan for it carefully. Here are the recommended steps for planning the first baseline:
Step 1. Determine what types of data to collect
When conducting the initial baseline, start by selecting a few variables that represent the defined policies. If too many data points are selected, the amount of data can be overwhelming, making analysis of the collected data difficult. Start out simply and fine-tune along the way. Generally, some good starting measures are interface utilization and CPU utilization. The figure shows some screenshots of interface and CPU utilization data, as displayed by a Fluke Networks network management system.
Step 2. Identify devices and ports of interest
The next step is to identify those key devices and ports for which performance data should be measured. Devices and ports of interest include:
Network device ports that connect to other network devices
Servers
Key users
Anything else considered critical to operations.
By narrowing the ports polled, the results are concise, and network management load is minimized. Remember that an interface on a router or switch can be a virtual interface, such as a switch virtual interface (SVI).
This step is easier if you have configured the device port description fields to indicate what connects to the port. For example, for a router port that connects to the distribution switch in the Engineering workgroup, you might configure the description, "Engineering LAN distribution switch."
Step 3. Determine the baseline duration
It is important that the length of time and the baseline information being gathered are sufficient to establish a typical picture of the network. This period should be at least seven days to capture any daily or weekly trends. Weekly trends are just as important as daily or hourly trends.
examples of several screenshots of CPU utilization trends captured over a daily, weekly, monthly, and yearly period. The work week trends are too short to accurately reveal the recurring nature of the utilization surge that occurs every weekend on Saturday evening when a major database backup operation consumes network bandwidth. This recurring pattern is revealed in the monthly trend. The yearly trend shown in the example is too long a duration to provide meaningful baseline performance details. A baseline needs to last no more than six weeks, unless specific long-term trends need to be measured. Generally, a two-to-four-week baseline is adequate.
You should not perform a baseline measurement during times of unique traffic patterns because the data would provide an inaccurate picture of normal network operations. You would get an inaccurate measure of network performance if you performed a baseline measurement on a holiday or during a month when most of the company is on vacation.
Baseline analysis of the network should be conducted on a regular basis. Perform an annual analysis of the entire network or baseline different sections of the network on a rotating basis. Analysis must be conducted regularly to understand how the network is affected by growth and other changes.

Measuring Network Performance Data
Sophisticated network management software is often used to baseline large and complex networks. For example, the Fluke Network SuperAgent module enables administrators to automatically create and review reports using its Intelligent Baselines feature. This feature compares current performance levels with historical observations and can automatically identify performance problems and applications that do not provide expected levels of service.

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