scope:

This standard defines Functional Element (FE) and Network Element (NE) reliability-related terminology, metrics, and features for evolving communications networks. The term reliability-related refers to "reliability, availability, maintainability and survivability." The standard is applicable to any layer 1 to 8 FE and NE.

Purpose

The purpose of this standard is to define a modernized and expanded set of reliability-related terminology, metrics, and feature definitions to facilitate the setting of clear, consistent and complete objectives. The intent is to have a standard that is non-implementation specific. The nomenclature and methodology defined is technology agnostic and not implementation specific.

This standard:

1. Specifies reliability-related objectives: Service Providers may use this standard to set reliabilityrelated requirements and Vendors may use this standard as input to product planning and design.

2. Compare objectives, predictions and actual reliability-related metric values for different Solutions: This standard may be used to characterize, compare and contrast reliability Solutions in a consistent way.

3. Facilitates risk management of critical reliability-related feature development: The design parameters of critical reliability-related features can be reported to the Service Provider by reporting outputs from the development process such as predictions and test results.

4. Facilitates tracking reliability-related in-service field performance: Vendors and Service Providers can track actual performance and compare them against objectives to drive corrective and preventive action plans.

Rationale

Many existing reliability-related terminology, metrics, and features have been exhaustively described in several documents (see clause 1.4). Many of the metrics were defined to support traditional voicebased public telephone networks and services where nodal failure mode objectives were set largely independently of how the NE was configured in the network. This standard builds on this body of knowledge by adapting existing definitions to suit network elements as the network is transformed to a converged multi-service packet-based network. Thus, this standard offers the convenience of consolidating the necessary set of reliability-related metrics and definitions, including expanding the metrics and features to reflect networking-related attributes.

By providing a consistent set of metrics and feature definitions, this standard will enable the comparison of various Solutions. The metrics incorporate both nodal and network reliability-related attributes for a more comprehensive set of reliability-related objectives. Lastly, since the document differentiates between external and internal reliability-related metrics, it provides vendors more flexibility to innovate to meet reliability-related objectives.