Faults and performance on a service
ITU-T G.8013/Y.1731 defines operations, administration and maintenance (OAM) functions for Ethernet networks. It covers fault management functions such as continuity checks and performance functions such as Ethernet frame loss and delay measurement.
A service may continue to pass continuity checks while user traffic experiences loss or variable delay. Performance measurements give operators observations to compare with a service objective or a healthy baseline.
Measure loss and delay between endpoints
A counter-based Ethernet loss measurement (ETH-LM) compares the number of frames sent and received in a direction over a measurement interval. The counter differences across successive samples provide an estimate of how many frames did not arrive.
Ethernet delay measurement (ETH-DM) uses timestamps to measure frame delay and delay variation. For one-way delay, the endpoints need synchronized clocks. A two-way measurement can avoid synchronizing the clocks between endpoints and reports delay for the combined forward and return paths.
Try it in a lab
- On equipment supporting Y.1731 measurements, establish CCM reception and record a healthy delay baseline between two service endpoints.
- Add controlled delay to the service in the lab. Repeat the measurement using the same direction and method. Verify that the measured delay rises while continuity remains healthy.
- Remove the added delay and compare the next samples with the original baseline.