Network Baselining
Network baselining overview

When networks are originally designed and installed, user requirements are gathered, analyzed, and translated into a network topology. The user requirements may be further extended into network performance goals such as bandwidth utilization, network latency and delay, and collision and error thresholds. To validate and document that the goals were achieved, specialized network monitoring and data collection is required. The process of network monitoring and data collection is called baselining.

Baselining allows discovery of the true performance and operation of the network in terms of the policies that have been defined. Performance trends and faults may be identified by comparing future performance metrics to the baseline metrics.

Establishing a baseline for a network provides answers to the following questions:

  • How does the network perform during a normal or average day?
  • Where are the under-utilized 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?

The purpose of conducting a network baseline is to measure the initial performance and availability of critical network devices and links in order to compare them to future performance. The baseline allows a network administrator to determine the difference between abnormal behavior and proper network performance. It also provides insight into whether the current network design can deliver the required policies.

Sophisticated network management software is often used to baseline large and complex networks. In simpler networks, the baseline tasks may require a combination of manual data collection and simple network protocol inspectors. The Fluke Protocol Expert is an example of one network protocol inspector. Shareware protocol inspectors can be downloaded from the Internet at http://www.statscout.com or other shareware sites. Selected examples of tools that may be used for baselining are discussed in Module 2, "Troubleshooting Methodologies and Tools"   .

The collected data will reveal the true nature of congestion or potential congestion in a network. It may also reveal areas in the network that are underutilized. Analysis after an initial baseline tends to reveal hidden problems and quite often can lead to network redesign efforts based on quality and capacity observations.

Without a baseline, no standard exists to measure the optimum nature of network traffic and congestion levels. Establishing an initial baseline or conducting a performance monitoring analysis may require many hours or days to accurately reflect network performance. Network management software or protocol inspectors and sniffers may run continuously over the course of the data collection process. Hand collection by way of show commands on individual network devices is extremely time consuming and should be limited to mission critical network devices.

The following sections describe the general methodology for defining, collecting, and reporting a network performance baseline. This entails the collection of key performance data from the ports and devices considered to be mission critical. The baseline is a vital preliminary step in determining the "personality" of the network.

The following are steps to building a baseline:

  • Planning for the first baseline
  • Identifying devices and ports of interest
  • Determining the duration of the baseline