Availability is also a commonly used measure for data services such as shared hosting, virtual private servers, and dedicated servers. Common agreements include percentage of network availability, availability, number of scheduled maintenance windows, and more. Since the late 1980s, SLAs have been used by fixed telecommunications operators. SLAs are so common these days that large organizations have many different SLAs within the company itself. Two different units in an organization write an SLA, one unit being the customer and another being the service provider. This approach makes it possible to maintain the same quality of service between the different units of the organization and also on several sites of the organization. This internal SLA script also makes it possible to compare the quality of service between an internal department and an external service provider.  The underlying advantage of cloud computing is the sharing of resources supported by the underlying nature of a shared infrastructure environment. Therefore, SLAs cover the entire cloud and are offered by service providers as a service-based agreement, not as a customer-based agreement. Measuring, monitoring, and reporting cloud performance is based on the end-user experience or its ability to consume resources. The disadvantage of cloud computing over SLAs is the difficulty of determining the cause of downtime due to the complex nature of the environment.
A service level agreement is an agreement between two or more parties, one being the customer and the other being the service provider. It can be a legally binding formal or informal “contract” (e.B. internal departmental relations). The agreement can include separate organizations or different teams within an organization. Contracts between the service provider and other third parties are often referred to as SLAs (wrongly) – since the performance level is set by the (principal) customer, there can be no “agreement” between third parties; These agreements are simply “contracts”. However, company-level or OLA-level agreements can be used by internal groups to support ASAs. If an aspect of a service has not been agreed with the customer, it is not an “SLA”. Service level agreements are also defined at different levels: it is not uncommon for an Internet backbone service provider (or Network Service Provider) to explicitly make its own SLA on its website.    The U.S. Telecommunications Act of 1996 does not explicitly require companies to have SLAs, but it does provide a framework for companies to do so in Sections 251 and 252.
 Section 252(c)(1), for example (“Duty to Negotiate”), requires incumbent local exchange carriers (SEAs) to negotiate in good faith on matters such as resale and access to transportation rights. Service level agreements can include many service performance metrics with corresponding service level objectives. A common case in IT service management is a call center or service center. Measures that are commonly accepted in these cases include: The main point is to build a new layer on the grid, cloud or SOA middleware capable of creating a negotiation mechanism between service providers and consumers….