A network element includes multiple interfaces and circuitry. The interfaces are configured to connect to a communication system. The circuitry is configured to receive via an ingress interface a packet that includes an Error Detection Code (EDC) field including an input EDC value, to determine an input timestamp indicative of a time-of-arrival of the received packet at the network element, and overwrite at least part of the input EDC value in the EDC field of the packet with the input timestamp, to estimate for the packet a traversal latency between reception at the ingress interface and transmission via a selected egress interface, based at least on the input timestamp, and to produce a deliverable version of the packet by writing an output EDC value to the EDC field, and send the deliverable version of the packet via the selected egress interface.