ITU-T Rec. X.137 (1988)
1 Introduction
2 Availability function
3 Availability parameters
3.1 Service availability definition
3.2 Definition of mean time between service outages
3.3 Values
3.4 Related parameters
ANNEX A – Sampling estimation of availability parameters
A.1 A minimal test for availability
A.2 Procedures for estimating service availability
A.3 Procedures for estimating mean time between service outages
ANNEX B – Representative end-to-end availability performance
B.1 Definition of the example end-to-end connections
B.2 End-to-end availability performance for the Type 1 and Type 2 configuration examples