In this talk, we will explore the idea of using the sketch data structure to summarize information about network flows, and then use the "sketch" to detect changes in the traffic pattern. The change detection is based on forecasting models such as EWMA and ARIMA. These models are typically used in time series forecasting and change detection. The paper first describes a variant of the sketch data structure called k-ary sketch and elaborates the technique to detect changes by performing certain operations on the data structure. Next, the paper describes the experimental results obtained by running experiments on real Internet traffic data. The authors compare the performance of the sketch based technique by running similar experiments on a per-flow basis. Finally, the paper concludes with a brief discussion of the ongoing work and future directions.