Recommendation ITU-T Y.2122 specifies the requirements and architecture for flow aggregate information exchange functions (FIXF). FIXF allows network domains to exchange flow aggregate information that reflects the current network conditions. In order to guarantee end-to-end QoS in NGN, cooperation among networks in an end-to-end path is necessary. Exchange of network configuration information is a key component of cooperation among participating networks. Flow aggregation has been considered a scalable technique for traffic management. Additional information obtained through FIXF can improve the accuracy of performance estimation and effectiveness of resource management.