code: func getDataPathPort(portNum uint32) (uint32, error) {
  	// if the value comes as 0 by any reason we set it to default value 4789
  	if portNum == 0 {
  		portNum = 4789
  		return portNum, nil
  	}
  	// IANA procedures for each range in detail
  	// The Well Known Ports, aka the System Ports, from 0-1023
  	// The Registered Ports, aka the User Ports, from 1024-49151
  	// The Dynamic Ports, aka the Private Ports, from 49152-65535
  	// So we can allow range between 1024 to 49151
  	if portNum < 1024 || portNum > 49151 {
  		return 0, fmt.Errorf("Datapath port number is not in valid range (1024-49151) : %d", portNum)
  	}
  	return portNum, nil
  }
docs: // getDataPathPort validates vxlan udp port (data path port) number.
  // if no port is set, the default (4789) is returned
  // valid port numbers are between 1024 and 49151