Measuring communication availability with Federal Standard 1033

The paper describes the technical concerns which influenced the development of a new Federal Standard 1033 which defines a set of digital communication performance parameters designed for a uniform means of specifying the performance of data communication systems. The paper also defines the availability parameters for the new standard in narrative and mathematical terms; the selected parameters are adaptations of the traditional reliability measures of mean time between failures and mean time to repair, but they are defined in such a way that they can be applied to any end-to-end digital communication service, irrespective of system-internal design or the pattern of service usage. This property makes the parameters useful as a common denominator for comparing alternative systems or services.