A method for performing a performance measurement on a multipoint packet flow transmitted in a subnetwork of a packet-switched communication network, said method comprising: a) implementing in said subnetwork a monitoring network comprising a plurality of measurement points (A, B... J); b) before transmitting each packet of said multipoint packet flow, marking said packet by setting a marking field thereof to a marking value equal to either a first marking value or a second marking value, said marking comprising periodically switching between said first marking value and said second marking value; c) at each measurement point (A, B,... J) of said monitoring network, receiving at least one of said marked packets and, if said at least one of said marked packets is marked by said first marking value, updating a performance parameter; d) providing said performance measurement on said multipoint packet flow, said providing comprising: - identifying in said monitoring network a cluster of measurement points (MN, C1, C2, C3, C4), said cluster of measurement points (MN, C1, C2, C3, C4) being a set of measurement points of said monitoring network selected so that, if no packet loss occurs, each packet received by at least one input measurement point of said cluster is also received at at least one output measurement point of said cluster; and - providing said performance measurement on said multipoint packet flow using performance parameters provided by said at least one input measurement point and said at least one output measurement point of said cluster (C1, C2, C3, C4) upon expiration of a marking period. a) implementing in said subnetwork a monitoring network comprising a plurality of measurement points (A, B... J); b) before transmitting each packet of said multipoint packet flow, marking said packet by setting a marking field thereof to a marking value equal to either a first marking value or a second marking value, said marking comprising periodically switching between said first marking value and said second marking value; c) at each measurement point (A, B,... J) of said monitoring network, receiving at least one of said marked packets and, if said at least one of said marked packets is marked by said first marking value, updating a performance parameter; d) providing said performance measurement on said multipoint packet flow, said providing comprising: - identifying in said monitoring network a cluster of measurement points (MN, C1, C2, C3, C4), said cluster of measurement points (MN, C1, C2, C3, C4) being a set of measurement points of said monitoring network selected so that, if no packet loss occurs, each packet received by at least one input measurement point of said cluster is also received at at least one output measurement point of said cluster; and - providing said performance measurement on said multipoint packet flow using performance parameters provided by said at least one input measurement point and said at least one output measurement point of said cluster (C1, C2, C3, C4) upon expiration of a marking period. - identifying in said monitoring network a cluster of measurement points (MN, C1, C2, C3, C4), said cluster of measurement points (MN, C1, C2, C3, C4) being a set of measurement points of said monitoring network selected so that, if no packet loss occurs, each packet received by at least one input measurement point of said cluster is also received at at least one output measurement point of said cluster; and - providing said performance measurement on said multipoint packet flow using performance parameters provided by said at least one input measurement point and said at least one output measurement point of said cluster (C1, C2, C3, C4) upon expiration of a marking period.