Guidelines to SLA modeling and establishment in heterogeneous communications networks

The question of how to specify, provide and measure service quality for network end-users has been of utmost interest for service and network infrastructure providers and their clients as well. The Service Level Agreement (SLA) is a beneficial tool in formalizing the interrelationships resulting from a negotiation among all participating actors with the target of achieving a common comprehension concerning delivery of services, its priorities, quality, responsibilities, and other relevant parameters. A horizontal SLA is an agreement between two service-providers existing at the same architectural layer (as for example two Internet Protocol (IP) or two Optical Transport Network (OTN) domains). A vertical SLA is an agreement between two individual providers at two different architectural layers (for instance, between an optical network and the core MPLS network). A service has to be defined without ambiguity utilizing Service Level Specifications (SLS) and three information types must be described: i) The QoX metrics as well as their corresponding thresholds; ii) A method of service performance measurement; iii) Service schedule. In this work we present preliminary simulation results that enable the development of a generic methodology for SLA modeling and establishment that will lead to a win-win situation for all involved actors. As an example, we put special attention in the benefits obtained by Optical Networks operators.