The service received by the customer as a result of the service provided is at the heart of the service level agreement. Sometimes maintenance services have to be closed. Depending on the thought effect on the service, two maintenance windows are used for system maintenance: Service level agreements are also defined at different levels: Definition: Significantly deteriorating service, but capable of performing most tasks on the system There are three types of service level agreements that can be documented. Before defining ITIL service level requirements and agreeing service levels via ALS, the most appropriate SLA structure must be designed. Depending on the services available to a customer or business, an SLA structure corresponding to the objective is designed. Service level agreements are usually signed during the ITIL service design phase of ITIL`s lifecycle. It is not uncommon for an internet service provider (or network service provider) to explicitly state its own ALS on its website.   The U.S. Telecommunications Act of 1996 does not specifically require companies to have ALS, but it does provide a framework for companies to do so in Sections 251 and 252.  Section 252 (c) (1) (“Duty to Negotiate”) obliges z.B. established local exchange operators (CIDs) to negotiate in good faith matters such as the sale of dentes` and access to whistleblowing channels. The third and final type of service level agreement is multi-level ALS. In multi-level ALS, aspects of ALS are defined by the client`s organization with a kind of heredition with global definitions relevant to all lower levels.
This ALS focuses on the client`s organization. All services and their relationships with subordinate services are used in defining the agree structure for multi-level service levels. In an agreement on the service level contract, it is stated what both parties want to achieve with their agreement, as well as an overview of each party`s responsibilities, including expected results with performance criteria. A service level agreement usually has a duration specified in the agreement. All services included in the agreement are described and may also contain details on procedures for monitoring the performance of services as well as on reflection procedures. FP7 IRMOS also examined aspects of translation of ALS terms at the application level into resource-based attributes to bridge the gap between customer expectations and cloud provider resource management mechanisms.   The European Commission has presented a summary of the results of various ALS research projects (from specifications to monitoring, management and implementation).  Since the late 1980s, ALS has been used by fixed-line operators. Today, ALS is so widespread that large organizations have many different ALSs within the company itself. Two different units in an organization script an ALS, one unit being the customer and another the service provider. This helps maintain the same quality of service between different units of the organization and in several sites within the organization. This internal ALS script also compares the quality of service between an internal service and an external service provider.
 Non-blocking maintenance means that the service is not completely reduced and remains available; However, compute controls may be interrupted during this maintenance, while the service is converted to another compute node. Cloud computing is a fundamental advantage: shared resources, supported by the underlying nature of a common infrastructure environment.