To determine normal reference traffic for a network, the ITU recommends that a network traffic analyst must take measurements for the busiest hour of each day for a whole year. The busiest hour is defined as that four consecutive quarter hours whose traffic intensity is the greatest. Measurements taken outside the busy hour can be discarded. The reference intensity of traffic is then calculated by taking the average traffic intensity of the top thirty days in the year. Measurements taken on individual days can be discarded. This will give the normal high traffic intensity in the network, allowing network managers to make long-term strategic decisions.