A network device is configured to implement a QoS function to optimize bandwidth utilization includes a memory configured to store a high priority throughput value and a low priority bandwidth value, a network device input to communicate a data stream including a plurality of data packets to and from at least one computer system on the internal network, and a network device output to communicate the data stream including the plurality of data packets to and from at least one computer system on the external network. The network device further includes a computer processor configured to execute steps stored in non-volatile memory, the steps including identifying high priority data packets in the data stream to detect the high priority throughput value, setting the low priority bandwidth value, and periodically adjusting the low priority bandwidth value. This QoS function can work without the knowledge of actual bandwidth for any link in the networks.