Techniques for testing a networked system using simulated abnormal node failure are disclosed. In some embodiments, a computer system performs operations comprising: repeatedly transmitting simulated requests to a networked system on which a software application is implemented using a plurality of nodes, the networked system being configured to respond to the simulated requests using the plurality of nodes; randomly selecting one or more nodes from the plurality of nodes; terminating the randomly selected one or more nodes; restarting the terminated randomly selected one or more nodes; repeating the randomly selecting one or more nodes, the terminating the randomly selected one or more nodes, and the restarting the terminated randomly selected one or more nodes until each one of the plurality of nodes has been terminated and restarted at least once during the first period of time; and determining response times of the networked system in responding to the simulated requests.

Techniques for testing a networked system using simulated abnormal node failure are disclosed. In some embodiments, a computer system performs operations comprising: repeatedly transmitting simulated requests to a networked system on which a software application is implemented using a plurality of nodes, the networked system being configured to respond to the simulated requests using the plurality of nodes; randomly selecting one or more nodes from the plurality of nodes; terminating the randomly selected one or more nodes; restarting the terminated randomly selected one or more nodes; repeating the randomly selecting one or more nodes, the terminating the randomly selected one or more nodes, and the restarting the terminated randomly selected one or more nodes until each one of the plurality of nodes has been terminated and restarted at least once during the first period of time; and determining response times of the networked system in responding to the simulated requests.

Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.

Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.

An error rate measuring apparatus includes an operation unit that sets one Codeword length and one FEC Symbol length of FEC according to a communication standard of a device under test W, a storage unit that stores symbol string data obtained by receiving and converting a signal from the device under test W, data division means for dividing the stored symbol string data into MSB data and LSB data, a data comparison unit that compares each of the divided MSB data and LSB data with error data to detect each of MSB errors and LSB errors of each one Codeword length, and detects FEC Symbol Errors of each of the MSB data and the LSB data at one FEC Symbol interval, and error counting means for counting the detected MSB errors, LSB errors, and FEC Symbol Errors.

Test entity for verifying user equipment (UE) device layer 2 sustained downlink maximum data rate decoding performance may send a non-access stratum message to the UE device that requests activation of a downlink-only test mode, sending a first Packet Data Convergence Protocol (PDCP) status request to the UE device, send downlink PDCP packets to the UE device during a measurement interval, receive a physical layer (PHY) hybrid acknowledge request (HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) from the UE device and determine expected missed layer 1 packets based on the received PHY HARQ ACK/NACK, send a second PDCP status request to the UE device after the measurement interval, receive a PDCP status report from the UE device, and determine missed layer 2 packets from a First Missing Count (FMC) value or bitmap included in the received PDCP status report.

Conventional test systems can experience issues when attempting to test network nodes or system with realistic high speed forward error correction (FEC) encoded test data. For example, a test system may use a packet data generator to generate eight data streams or lanes of 50 Gigabits per second (Gbps) test data and may then use a multiplexer to combine the eight lanes into a 400 Gbps data stream for transmission using 4-level pulse amplitude modulation (PAM4). To generate a high speed data stream comprising multiple data lanes, the test system may be required to use a master clock or other time synchronization technique to keep the data lanes in sync. Further, to generate an FEC encoded high speed data stream comprising multiple data lanes, the test system may perform FEC encoding across all of the data lanes comprising the high speed data stream, which can make test data modifications difficult afterwards. Hence, issues can arise if a packet data generator lacks capabilities, e.g., analog distortion or analog fuzzing features, that are needed for testing some aspect of network node functionality.

An error rate measuring apparatus includes an operation unit that sets one Codeword length and one FEC Symbol length of FEC according to a communication standard of a device under test W, a storage unit that stores symbol string data obtained by receiving and converting a signal from the device under test W, data division means for dividing the stored symbol string data into MSB data and LSB data, a data comparison unit that compares each of the divided MSB data and LSB data with error data to detect each of MSB errors and LSB errors of each one Codeword length, and detects FEC Symbol Errors of each of the MSB data and the LSB data at one FEC Symbol interval, and error counting means for counting the detected MSB errors, LSB errors, and FEC Symbol Errors.

A data communication device includes a host receive section for receiving incoming host data from a host device. The host receive section includes a plurality of host receive lanes. A host transmit section for transmitting outgoing host data to the host device includes a plurality of host transmit lanes and a host cross point section. A line receive section for receiving incoming line data from a line device includes a plurality of line receive lanes. A line transmit section for transmitting outing line data to the line device includes a plurality of line transmit lanes and a line cross point section. A link monitor section coupled to the host transmit section and the line receive section is configured to detect errors between the host transmit section and the line receive section.

Test entity for verifying user equipment (UE) device layer 2 sustained downlink maximum data rate decoding performance may send a non-access stratum message to the UE device that requests activation of a downlink-only test mode, sending a first Packet Data Convergence Protocol (PDCP) status request to the UE device, send downlink PDCP packets to the UE device during a measurement interval, receive a physical layer (PHY) hybrid acknowledge request (HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) from the UE device and determine expected missed layer 1 packets based on the received PHY HARQ ACK/NACK, send a second PDCP status request to the UE device after the measurement interval, receive a PDCP status report from the UE device, and determine missed layer 2 packets from a First Missing Count (FMC) value or bitmap included in the received PDCP status report.