In one embodiment, a message is received at a node in a network indicating that the node is classified as a critical node, and requesting the node to proactively time-stamp data packets. Data packets are received from one or more child nodes of the node, and the node selects a data packet of the received data packets to time-stamp. Then, the node proactively inserts a time-stamp in the selected data packet. The time-stamped data packet is sent toward a central management node.