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