The present invention provides a method for avoiding demand forecast errors in a network topology model having a plurality of nodes, by monitoring and controlling the quantity of a selected port type at a node. The method comprises determining the actual quantity of a selected port type at a node, setting a forecast of the quantity of the port required, setting a forecast period for the ports, wherein the forecast period is a function of the time required to change the quantity of the ports, and setting a threshold value to generate alerts, wherein the threshold value is a function of the forecast period; monitoring the node for a forecast change, if a forecast change is found then computing the difference between the actual quantity and the forecast quantity, wherein if the difference is greater than the threshold value, then generating an alert and forwarding the alert to a user.