Unavailable Seconds (UAS)

The Unavailable Seconds (UAS) metric indicates during how many seconds of some interval the service can be considered to have been unavailable. ► ITU-T Recommendation Y.1563 defines UAS based on the concept of Severely Errored Seconds (SES). A period of unavailability starts with 10 consecutive SES and ends with 10 consecutive non-ES. Those first 10 consecutive SES are part of the period of unavailability. See the diagram below, taken from Y.1563, for an illustration:

Paragon Active Assurance presents the total number of UAS, i.e. the total number of seconds during which the network has been in the unavailable state during the test or monitoring session that is currently running.

Note

For the TWAMP task, the SES threshold is configurable, as explained here. For all other tasks that produce the UAS metric, the SES threshold is fixed at 10 seconds as described above.