5.3	Recommendation I.352

NETWORK PERFORMANCE OBJECTIVES FOR CONNECTION PROCESSING

DELAYS IN AN ISDN

1.	General

1.1	Reference model

This Recommendation provides network performance objectives for connection processing delays. The reference model provided in Recommendation I.34X was used to provide a baseline reference configuration. In addition Recommendation Q.709 was taken into account in the determination of values.

Note - This Recommendation does not take into account the performance of private networks. In case of private networks connected to the ISDN the recommended values refer to the T reference point. The S reference point applies in cases where S and T are coincident.

1.2	Measurement

All parameter values are specified at network boundaries. These values are measured at the ISDN S/T reference points using call processing message transfer events (MTEs) (Recommendation Q.931 messages or the corresponding Signalling System No. 7 messages), where appropriate.

1.3	Network conditions

The values for delay given in this Recommendation include an allowance for the effects on delay that might be introduced during a nominal busy hour. Consideration was given to the possibility that individual busy hours might not be coincident. The values also include the effects of network component failures. The specified values do not apply under conditions of network unavailability. These delays are expressed in terms of mean and 95% probability values.

1.4	User delay

Values are provided for measurements made at a single connection element boundary as well as measurements made between two connection element boundaries. This allows for calculations that would avoid inclusion of any delay that might be introduced by users or user equipment.

1.5	Allocation

Overall connection processing delays between S/T reference points can be divided into sub-values for each connection element including the national and international portions.

1.6	Basic connection

Connection processing delays are only defined for a basic connection and therefore do not provide for any effects that might be introduced by supplementary services. (See Figure 1/I.352).

1.7	Phases

Connection processing delay values are specified for the connection set-up and disconnection phase.

FIGURE 1/I.352

Procedure for a simple circuit switched call (example)