SLA definition for the provision of an EF-based service

The evolution of mechanisms for providing Quality-of-Service (QoS) over the contemporary network infrastructures has introduced the need for regulation and management of the emerging QoS services with the use of Service Level Agreements (SLAs). SLAs for QoS-enabled networks move one step forward in the direction of traditional ones, in the sense that they do not only have to specify availability, security, quantity of allocated resources and a number of other quantitative values but also have to specify the values of appropriate quality parameters. This paper deals with the particular cases of introduction of QoS mechanisms to large transport networks according to the DiffServ architecture. In these cases, the extensive level of aggregation of flows and the connectionless nature of QoS services’ provisioning makes the definition of QoS parameters and the engineering of QoS metrics in the traditional SLA specification a demanding task. Due to the fact that strictly bounded deterministic guarantees are not realistic, usually only upper bounds for the relevant parameters can be defined and the corresponding SLAs have to be defined accordingly.