Service Uptime is the proportion of time, during a given time period Tk, that the service is working from the perspective of the Subscriber, excluding any pre-agreed exceptions, for example, maintenance intervals. The value of this Service Attribute is a 3-tuple <ts, T, U> where:
- ts is a time that represents the date and time that evaluation of Service Uptime starts for the SWVC
- T is a time duration, e.g., 1 month or 2 weeks, that is used in conjunction with ts to specify time intervals for determining when the Service Uptime Objective is met. Note that the units for are not constrained; in particular, “1 month” is an allowable value for , corresponding to a calendar month, e.g., from midnight on the 10th of one month up to but not including midnight the 10th of the following month.
- U is the objective for Service Uptime expressed as a percentage.
The time intervals are specified by the parameters ts and T in the value of this Service Attribute. One time period, denoted T0, starts at time ts and has duration T. Each subsequent time period, denoted Tk, starts at time ts + kT where k is an integer, and has duration T; in other words, each new time period starts as soon as the previous one ends. Service Uptime is evaluated for each time period Tk, so one can say that for a given Tk, the performance objective is either met or not met
The definition of Service Uptime is expressed in [R14].
[R14] The Service Uptime for an SWVC during time period Tk MUST be defined as follows:
- Let O(Tk) be the total duration of outages during the time period Tk.
- Let M(Tk) be the total duration of maintenance periods during the time period Tk.
- Then define the Service Uptime U(Tk) =
An example of the value for this Service Attribute would be:
<”10-Jul-2018 00:00:00”, “1 month”, 99.8%>
[R15] The SWVC Service Uptime Objective for a given time interval, Tk, MUST be considered met if U(Tk) is greater than or equal to the element in the value of this Service Attribute for time interval Tk.
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