A network management system, for example for use in a telecommunications network, comprises a performance measurement tool for carrying out a plurality of performance measurements relating to physical or logical components of the network. Prior to hand-over of the mobile node in response to its movement, a service context is transferred to APs arranged in a moving direction of the mobile node based upon context transfer policies according to the determined AP types. The clipping member has pawl structures spaced in an annular manner and formed in a conical structure. The hook has a shank and a barbed point, the shank being fixedly attached to and extending from the paddle such that the hook lies on the same vertical plane as the paddle, and such that the hook extends rearwardly opposite the direction of movement. Additionally, in accordance with an exemplary embodiment of the invention, labels corresponding to the data content may be presented in an index in a specialized format based on the discrimination criteria. The observation circuits determine the number of lost packets across a node and between nodes, according to an aggregate definition.