Page 521 - Handbook of Modern Telecommunications
P. 521

4-52                    CRC Handbook of Modern Telecommunications, Second Edition

              A Service-Level Agreement is a formal negotiated agreement between two parties. It is a contract that
            exists between the service provider and the customer or among multiple service providers or between
            service providers and network operators. It is designed to create a common understanding about ser-
            vices, priorities, and responsibilities.
              A Service-Level Agreement should also cover corrective actions; that is, the steps to be taken in the
            event that a service-level objective is not met. This section of the contract should define who resolves the
            problem of each service deficiency, as well as consequences for not resolving the problem. Consequences
            can appear in the form of penalty clauses or alternatively a bonus clause for meeting the objectives. The
            end result will be the same.
              Service-Level Agreements can cover many aspects of the relationship between the customer and the
            service provider, such as quality and performance of services, customer care, billing, and provisioning.
            Performance reporting uses the Service-Level Agreement as a reference, but does not address the other
            parameters known to exist as part of the Service-Level Agreements.
              Service-Level Agreements (SLAs) are an excellent tool for customer and service provider manage-
            ment. A well-crafted SLA sets and manages expectations for all elements of the service to which it
            refers. It assists the service provider in forcing operational change, improving internal measurement
            and reporting, assessing trends, improving customer relationships, and provides a vehicle for potential
            differentiation from its natural competitors.
              Quality of service (QoS) parameters can be used to quantify the quality of service and are included
            in SLAs. In selecting quality of service metrics for SLAs, the following criteria should be considered:
              •   Importance of the metric for operations
              •   Ease of measurement
              •   Providing basis data for reporting
              •   Quantification of the service
              •   Importance of the metric for business applications
            4.4.2.1  Service-Independent Metrics
            Examples of service-independent metrics are outlined below.
              Availability for:
              •   Service access points
              •   Applications
              •   Devices
              •   Transmission facilities
              Mean time to service restoration for:

              •   Service access points
              •   Applications
              •   Devices
              •   Transmission facilities
              Mean time between failures for:

              •   Service access points
              •   Applications
              •   Devices
              •   Transmission facilities

              Mean time to repair for:
              •   Service access points
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