MEF Services, such as SD-WAN, are specified using SD-WAN Service Attributes. A Service Attribute captures specific information that is agreed on between the Service Provider and the Subscriber of a MEF Service, and it describes some aspect of the service behavior. How such an agreement is reached, and the specific values agreed upon, might have an impact on the price of the service or on other business or commercial aspects of the relationship between the Subscriber and the Service Provider; this is outside the scope of the MEF 70 standard. Some examples of how agreement could be reached are given below, but this is not an exhaustive list.
The provider of the service mandates a particular value.
The Subscriber selects from a set of options specified by the provider.
The Subscriber requests a particular value, and the provider accepts it.
The Subscriber and the Service Provider negotiate to reach a mutually acceptable value.
Service Attributes describe the externally visible behavior of the service as experienced by the Subscriber and also the rules and policies associated with how traffic is handled within the SD-WAN Service. However, they do not constrain how the service is implemented by the Service Provider, nor how the Subscriber implements their network.
The initial value for each Service Attribute is agreed upon by the Subscriber and the Service Provider in advance of the service deployment. The Subscriber and the Service Provider may subsequently agree on changes to the values of certain Service Attributes. MEF 70 standard does not constrain how such agreement is reached; for example, if the Service Provider allows the Subscriber to select an initial value from a pre-determined set of values, they might further allow them to change their selection at any time during the lifetime of the service.