# The Firmware Design and Implementation Scheme for C Form-Factor Pluggable Optical Transceiver +
## 4 Evaluation and Result
### Results
#### 4.2.2 Performance Test Result  
Figure 13 shows the results for the data throughput through the CFP test bed. The CFP transceiver was loaded to transmit and receive 99% of the available bandwidth. The test results confirmed that  
Figure 11: Access of CFP Memory Map. Figure 12: Results of Digital Diagnostic Monitoring (DDM) and Alarm. the data were transmitted and received without error at a utilization of more than 99%. Figure 14 shows the results of a long-term test for the safety and reliability of optical transceivers produced by the proposed firmware technique. It was verified that the operation was stable for more than 144 h without errors. To verify the performance of the DDM function, we measured the received optical power DDM of the CFP transceiver for each channel. By adjusting the optical power input into the CFP transceiver using a variable attenuator, the received optical power DDM accuracy was measured over several sections. Figure 15 shows the received optical power DDM value of each channel measured for input optical powers ranging from \(-3\) dBm to \(-15\) dBm. All channels are within the margin of error, and channel 4 has the highest accuracy of 93.4%. By section, the accuracy is the highest when the optical power of \(-9\) dBm is received. The accuracy trend varies depending on the characteristics of the optical component. Figure 14: Reliability Test of the CFP Optical Transceiver. Figure 13: Throughput of the CFP Optical Transceiver. Figure 16 shows a measurement graph of the received optical power DDM before (a,c,e,g) and after (b,d,f,h) the temperature calibration at high temperature and low temperature. The measurement indicates that the DDM value is reading lower and lower as the temperature goes from low to high. Therefore, the accuracy of DDM becomes lower when it is in low temperature and high temperature environment. For channels 3 and 4, the low temperature DDM value before temperature calibration is close at the upper limit of the error range. However, the graphs of the results of applying the temperature calibration method proposed in this paper all have sufficient margins in the margin of error. This result is show that the application of the temperature calibration method proposed in this paper can maintain high DDM accuracy even in the change of optical component properties with temperature. Figure 17 shows the received optical power DDM accuracy of the proposed firmware and a conventional commercial CFP transceiver. Unfortunately, the methods for calculating DDM in existing CFP are not disclosed, so technical differences cannot be compared, but they can be compared by measuring DDM accuracy. The results show that the DDM accuracy of an existing CFP product is higher than that of the proposed scheme in some channels, but the accuracy in all channels with the proposed method is higher than that of an existing CFP transceiver. Moreover, the results confirm that the deviation of the DDM accuracy among the channels in the proposed firmware is less than that resulting from the conventional method. Finally, the advantages of the proposed firmware design are summarized in Table 4. The proposed technique allows up to 16 channels to be expanded using the FPGA and can flexibly expand external chips depending on the required functions. The external ADC/DAC chips are used, and communication interfaces are implemented, if high-end ADC/DAC chips are required, external chips can be changed without MCU replacement. Furthermore, the implementation of the CFP standard memory in the FPGA is hardware separated from the MCU. This method can ensure the optical transceiver stability by being managed by the FPGA to allow access to the CFP standard memory from outside, even if there is a temporary problem with MCU operation. Our proposed method also used vendor IOport (Vendor IOport) on CFP standard connectors to help update the FPGA and MCU, and to allocate serial interfaces to debug the optical transceiver. Figure 15: Graph of Rx power DDM. Figure 16: Graph of Rx Power DDM about Temperature Calibration.