This Recommendation describes measurements that are applicable to: 1) provider delivery assurance of customer network performance; 2) providers to supply performance information for prospective customers; 3) provider troubleshooting among networks along defined paths; 4) provider internal indication of performance impact of changes within networks; 5) provider monitoring of performance of other network operators; 6) providing information to other network components@ e.g.@ automated network management. This Recommendation covers active and passive measurement and combinations of these two techniques. Active measurement employs packets dedicated to the measurement function inserted at one measurement point (MP) and collected at a remote MP. Passive measurement usually involves observations of user packet traffic at one or more MPs. Spatial measurement is a special category of active measurement that employs both active and passive techniques. It utilizes observations of measurement-dedicated packets at three or more MPs@ where one or more point(s) simply monitor(s) [and do(es) not terminate] the test packets. This Recommendation presents requirements for performance measurement including performance attributes and time-scales. Building upon existing standards@ it recommends best practice in these areas based on [ITU-T Y.1540]. Comparisons with IETF RFC standards are included. This Recommendation also defines one possibility for the probe packet format@ based on [IETF RFC 5357]. This Recommendation describes a network model that locates key points of demarcation and measurement. It categorizes various measurements and shows how they may be applied to the network model. It reviews time synchronization and sets targets for equipment that is located at various points in the network model. Security requirements for measurement traffic are analysed@ approaches are considered@ and then a set of approaches is selected. The security of the border gateway protocol (BGP)@ synchronization systems and customer equipment lie outside the scope of this Recommendation. Customer interactions with their service provider (SP) are discussed at a high level. Details of transferring results to customers lie outside the scope of this Recommendation. The target networks of this Recommendation are IP networks@ including those enabled by multiprotocol label switching (MPLS); pure layer 2 (L2) and other non-native IP networks lie outside the scope of this Recommendation. This Recommendation specifies how to measure the minimally required set of metrics to determine network performance. Specification of advanced analysis and dissemination of measurement data lie outside the scope of this Recommendation. Impairment allocation and mapping performance among IP and non-IP networks lie outside the scope of this Recommendation. Methods to determine the exact network path that packets will follow lie outside the scope of this Recommendation.