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The development of higher speed Internet connections and improvements in streaming media technology promise to increase the volume of streamed media over the Internet. The performance of currently available streaming media products will play an important role in the network impact of streaming media. However, there are few empirical studies that analyze the network traffic characteristics and Internet impact of current streaming media products. This paper presents analysis from an empirical study of the two dominant streaming multimedia products, RealNetworks RealPlayer™ and Microsoft MediaPlayer™. Utilizing two custom media player measurement tools, RealTracker and MediaTracker, we are able to gather application layer and network layer information about RealPlayer and MediaPlayer for the same media under the same network conditions. Our analysis shows that RealPlayer and MediaPlayer have distinctly different behavior characteristics. The packet sizes and rates generated by MediaPlayer are essentially CBR while the packet sizes and rates generated by RealPlayer are more varied. During initial delay buffering, MediaPlayer sends data at the same rate as during playout while RealPlayer can buffer at up to three times the playout rate. For high bandwidth clips, MediaPlayer sends frames that are larger than the network MTU, resulting in multiple IP fragments for each application level frame. From the application perspective, for low bandwidth clips, MediaPlayer has a lower frame rate than RealPlayer. Our work exposes some of the impact of streaming media on the network and provides valuable information for building more realistic streaming media simulations.