Packetizing scalable streams in heterogenus peer-to-peer networks After the extensive effort dedicated by both Academia and Industry in the area of peer-to-peer (P2P)streaming by looking at models and network algorithms to achieve optimal load distribution, recent works are moving forward to enhance the overall P2P systems efficiency by focusing on specific video codecs and packetization techniques at application layer. The purpose to integrate different technologies with the aim to design full streaming solutions requires a joint efforts from the market and EU projects community. Many engineering issues have been brought out in terms of compatibility and integration that need to be addressed. In this paper we focused on a bottleneck discovered during the packetization step between the Scalable Video Coding (SVC) streaming module (during content creation) and the P2P engine before delivering the packets over the network. We compared the a priori fixed packet size solution adopted in P2P-Next project with a codec aware approach, gaining performance in terms of network overhead. We performed experiments with various sequences aiming at overall P2P streaming efficiency and measured the bandwidth cost under various conditions. Since we focused on the application layer, our statistics analysis can be helpful in designing P2P streamingsolutions dealing with any network type.