Evaluation and testing of 400G Ethernet equipment

Evaluation of 400G Ethernet Equipment

Until now, testing and evaluation of 400G Ethernet equipment has been based on evaluating performance, such as throughput and latency, etc., in the same manner as network equipment. Adding this option to the Network Master Pro MT1040A supports evaluation of fundamental Ethernet parameters by connecting the 400G Ethernet equipment to two ports.

【Video】MT1040A 400G Dual-port/100G 4-port Measurements

Click here for leaflet

Moreover, as well as evaluating and testing 400G equipment performance, such as throughput and latency, etc., output signal quality must also be evaluated.

Evaluation of Equipment Output Signal Quality

At evaluation of the equipment output signal quality, the optical signal from the equipment is input to the MT1040A for FEC distribution analysis, which confirms the equipment output signal quality by displaying a distribution graph of any Symbol Errors occurring in one codeword.

About details on the FEC evaluation

The signal quality becomes worse as more Symbol Errors occur per codeword.

The output signal quality at Layer 1 depends on the combination of the optical transceiver signal performance and the electrical signal quality of the equipment in which the transceiver is installed. As a consequence, evaluation requires using the optical transceiver and equipment as a set.

Evaluation of Optical Transceiver Output Signal Quality

When evaluating the standalone optical transceiver signal quality, the optical transceiver is installed directly in the MT1040A with an optical-fiber loopback connection at the transceiver to perform FEC distribution analysis.

At evaluation, the pre-emphasis is set at the MT1040A side, and the pre-emphasis and equalizer settings for optical transceivers, such as QSFP-DD, are changed to evaluate whether or not the signal quality changes. The FEC distribution analysis is the most effective evaluation item for confirming the most suitable values for these parameters.

400G Degraded SER Evaluation

Since 400G Ethernet uses FEC error correction to implement error-free operation, signal deterioration in the transmission path cannot be detected. As a consequence, countermeasures cannot be taken, because faults in the transmission path cannot be recognized until they suddenly become very serious when even FEC error correction cannot solve the situation.

It is very important for the line-operation side to quickly discover signal deterioration and faults. Consequently, IEEE802.3 specifies a function called 400G Degraded SER, which continuously monitors the SER of received signals and when the signal deterioration exceeds a set threshold value, the deterioration condition is detected and a deterioration alarm (called remote degraded or RD) is sent to the send source. However, installation of this 400G Degraded SER function is only optional and whether it is installed or not depends on the equipment vendor.

The function for evaluating 400G Degraded SER is built-in to the MT1040A as standard.

This function demonstrates its usefulness both at equipment development and at actual testing and evaluation of in-service equipment.