US Patent 7142518 Monitoring communications networks

Selected data (LSP1, LSP2) is monitored among other data passing through label switched paths (LSPs) of a communications network of interconnected label switching routers (LSR–LSR4). The method comprises designating at least one of the routers (LSR3) as a monitoring station and at least one of the routers (here LSR3 also) as a probe interface station, and connecting a probe apparatus to that interface station. The monitoring station (LSR3) is configured to multicast forward the selected data for monitoring additionally to the probe apparatus via the probe interface (506). Also disclosed is a probe apparatus including means for configuring the router to perform multicast forwarding of selected data to the interface.