The paper presents the architecture of a measurement system designed to reside into DiffServ/MPLS Linux based routers. The goal of this research is to develop an open source software product to be used for management purposes and to be integrated in the network control plane in order to automate resource allocation, admission control and Traffic Engineering functionalities. The system is designed to be flexible, configurable and modular and each module has been implemented in order to minimize the impact of the system itself on the traffic dynamics. The output of the system is a sequence of measurements that report the amount of per-PHB and per-LSP traffic offered to the router over a configurable time window. The system allows to perform prediction on the future traffic activity as well as trigger asynchronous threshold crossing events. The system has proven to be reliable as it passed several functional tests. Preliminary experimental results have shown that the output of the system accurately captures the traffic patterns offered to the router.