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| 1.1 |  | Network Baselining |
| 1.1.4 |  | Determining the duration of the baseline |

IIt is important that the length of time and the baseline information being gathered is sufficient to establish a typical picture of the network. This period should be at least seven days, in order to capture any daily or weekly trends. Weekly trends are just as important as daily or hourly trends.

As an example, the engineers in Building 7 run a massive backup and software refresh, on Sundays at 2 A.M., on all 200 of their workstations. Because the backup server happens to be in Building 9, the push and backup saturate the corporate backbone. If the baseline was only performed from Monday through Friday, the saturation would be missed.

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.

Examples of baselines for CPU utilization over various intervals of time can be provided by the Multi Router Traffic Grapher (MRTG). This tool can be found at http://mrtg.hdl.com/mrtg.html.

It is recommended that baseline measurement is not performed during times of unique traffic patterns. As an example, it would not be beneficial to perform the baseline over a holiday or during December if most of the company is on vacation.

However long the initial baseline is chosen to last, plan to try different durations on subsequent baselines. This will allow discovery of the optimal analysis collection interval for the network.