Once again, SLAs are contracts between service providers and customers that define the services provided, the metrics associated with these services, acceptable and unacceptable service levels, liabilities on the part of the service provider and the customer, and actions to be taken in specific circumstances. The service provider may be a traditional carrier or another group in the company that provides the network services. Service-level management is the set of people and systems that allow the organization to ensure that SLAs are being met and that the necessary resources are being provided efficiently. In the telecommunications management network (TMN) model, service management logically resides above the element and network management layers and below business management (see Figure 1). SLAs are critical success factors in terms of differentiating and ensuring service delivery.

Figure 1. Service Management’s Role in the TMN Model

The definition of the SLA is important in terms of defining customer expectations. Most SLAs are developed after first baselining existing services and then by defining what, if any, new services are required. An SLA is intended to be an objective tool that helps service providers define benefits versus cost tradeoffs and deliver communication services that provide the best value to the customer.

Traditional approaches to service management involving event filtering, correlation, and even root-cause analysis, simply fall short. They cannot handle the dynamic complexity of today’s networks and cannot automate the labor-intensive, time-consuming steps required to investigate and correct each potential problem. Some products do a good job of displaying data, but most of the burden still falls on the operators, who must still perform all tests, diagnose the cause, measure the business impact, and then decide on and execute an appropriate response. The biggest challenge is to ensure that one measures and manages the parameters that matter (not just those that are readily available), meaning those that impact the service as defined in the SLA. This means being able to collect low-level equipment, network, and application data and combine it into service data, given that single, easily measured and managed service attributes do not often present themselves.