Exemplary embodiments for use in a communications source network node for identifying a destination port associated with a destination network node to which a selected network link is connected. The embodiments include receiving a communications protocol packet at a destination network node via said selected network link connected to the destination port associated with the destination network node; inspecting the packet for a predetermined identifier; and if the predetermined identifier is present in said packet then outputting an indication that the identifier has been received comprising an identification of the destination port via which the packet was received. The indication is output by at least one of illumination for a pre-set period of a destination switch associated with the destination port, and by an output provided via a user interface of a network interface controller associated with the destination port.