A source node can append a unique identifier to an outbound client packet, transmit the outbound client packet to a recipient node via a port, and create a transmission record including: the unique identifier, a time stamp of the outbound client packet, and an identifier for the port. The source node can receive an inbound client packet that is appended with the unique identifier and a delta time indicating an amount of elapsed time between the recipient node receiving the outbound client packet and the recipient node transmitting the inbound client packet. The source node can determine a performance level of a VPN tunnel provided by the port based on the time stamp value of the outbound client packet, the delta time, and a time stamp value of the inbound client packet indicating a time at which the inbound client packet was received by the source node.