Mapping between QoS Parameters and Network Performance Metrics for SLA monitoring

Service Level Agreement (SLA) is a formal negotiated agreement between a service provider and a customer. The service level management (SLM) is the integrated management of all functionalities in the SLA life cycle. When a customer orders a service from a service provider, an SLA is negotiated and then a contract is made. In the SLA contract, QoS parameters that specify the quality level of service that the service provider will guarantee are included. The service provider must perform SLA monitoring to verify whether the offered service is meeting the QoS parameters specified in the SLA. SLA monitoring involves monitoring the performance status of the offered service and provide relevant information to the service level management system. In order for the service level management system to verify whether the specified QoS parameters are being met, the system must gather performance data from the underlying network performance monitoring system and map such data to the QoS parameters. In this paper, we propose a formal mapping mechanism between QoS parameters in SLA and the network performance metrics. Although we focus on the network access service (e.g., leased-line service, xDSL service, VPN service) in this paper, we believe that our mapping mechanism can be easily used in SLA monitoring of other services (such as application, server hosting, contents). We also propose a general SLA monitoring system architecture that can be used to monitor service levels for various services offered by network, Internet and application service providers. We then present how our SLA monitoring system architecture can be used for SLA monitoring of IP backbone network service. Keyword: SLA, Service Level Management, SLA monitoring, QoS parameter, Network Performance Metric, Measurement Mapping, Evaluation Mapping 2002 APNOMS 2 POSTECH DP&NM Lab Introduction Increased Importance of SLA Liberalization and rapid evolution of the telecommunication market Increased interest in service quality by customers Aggregated view of service behavior provided by SLA monitoring Various research on network monitoring Problem Lack of Systematic QoS parameter to Network Performance Metric Mapping Lack of Generalized SLA monitoring System Architecture Goals of Our Research Define the concept of SLA monitoring Define QoS parameter to Network Performance Metric Mapping Design of Generic SLA monitoring System Architecture SLA is a formal negotiated agreement between a service provider and a customer. Usually in measurable terms, SLA is defined as the quality of services the service provider will provide [1]. The liberalization and rapid evolution of the telecommunication market is one of the major reasons for the increased significance of SLA. By the supported service of SLA, the service provider can differentiate itself from its competitors and prioritize service improvement opportunities. From the viewpoint of the consumer, he may desire to access a service of his own inclination and to validate the quality of the service provided. This is another reason for the increased importance of SLA. The SLA life cycle consists of the following 5 phases: product/service development, negotiation and sales, implementation, execution, and assessment [2]. The service level management (SLM) is the integrated management of these five phases in the SLA life cycle. With the importance of SLM, its concept and methods are mentioned in many other papers [13, 18, 19, 20]. SLA provisioning and SLA monitoring are critical parts to realize the SLA supported service in the network management layer. SLA Provisioning is to configure the network and system infrastructure for quality insured service. In the network service area, many networking technologies such as MPLS [3] and Diffserv [4] have been proposed, and much valuable research has been performed [3, 21] for QoS-based traffic treatment. The role of SLA monitoring is to monitor the service status for each customer according to the agreed QoS Parameters in SLA and to provide a basis for the billing and reporting system. Although much research on network monitoring has been performed and the result of network monitoring is very essential to SLA monitoring, it lacks a consideration of how to apply the result of network monitoring to SLA monitoring. And many service providers use their own proprietary SLA monitoring methods. So, further consideration about standardized SLA monitoring method is needed. Also the general guideline for SLA monitoring is necessary for the service providers who newly start to launch SLA based services. TM Forum mentioned the importance of SLA monitoring, but did not present the details of SLA monitoring sequence or its architecture [2]. In this paper, we categorize SLM into seven functions. We define the concept of SLA monitoring in the network management layer. The most important factor in SLA monitoring is the mapping between QoS Parameters and network performance metrics (NPMs). We also define the concept of this mapping and the requirements of a SLA monitoring system. From this concept we present a generic SLA monitoring system architecture. To validate our theory we applied our design to an IP-backbone network service. 2002 APNOMS 3 POSTECH DP&NM Lab SLM and SLA monitoring QoS Parameters QoS Parameters SLA Contract SLA Contract Problem Notification Problem Notification Performance Data Performance Data