Abstract: A method and apparatus for analyzing traffic arriving at and/or departing from a traffic aggregate defined as a given IP-related protocol, a given port associated with a given protocol, an IP address or subset of IP addresses, or by other traffic aggregation, during a given time interval, to determine whether there is a significant increase or decrease in traffic aggregate's traffic volume as compared to the traffic aggregate's expected traffic volume are disclosed. In one embodiment, the present method defines a traffic share ratio threshold associated with a given protocol or a given protocol port or a given IP address or a given subset of IP addresses or other traffic aggregation using said collected volumetric traffic data. The present method also defines a current traffic share, a baseline traffic share and a traffic share ratio to be evaluated for the said traffic aggregate.