WBEM-based SLA Management across multi-domain networks for QoS-guaranteed DiffServ-over-MPLS Provisioning

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1 WBEM-based SLA Management across multi-domain networks for QoS-guaranteed DiffServ-over-MPLS Provisioning Jong-Cheol Seo 1, Hyung-Soo Kim 2, Dong-Sik Yun 2, Young-Tak Kim 1, 1 Dept. of Information and Communication Engineering, Graduate School, Yeungnam University 214-1, Dae-Dong, Kyungsan-Si, Kyungbook, , KOREA 2 Network Technology Laboratory, System Architecture Research Division, Solution Research Department, Korea Telecom (KT) 463-1, Jeonmin-dong, Yuseong-gu, Daejeon, , Korea sjc2305@paran.com, essence@kt.co.kr, dsyun@kt.co.kr, ytkim@yu.ac.kr Abstract. For QoS guaranteed DiffServ-over-MPLS connection provisioning in multi-domain networks, the managed objects in each domain should be globally standardized and publicly accessible by other NMSs. And each NMS participating in the inter-domain networking should negotiate with other NMSs for end-to-end service provisioning. In this paper, we propose SLA negotiation by COPS protocol and design the managed objects by expanding existing experimental DMTF CIM MOFs. We propose service location protocol based directory agent to register/discover the NMSs that participate in the multi-domain TE-LSP connection provisioning. For better performance, we design the multi-threaded provider implementations on OpenPegasus WBEM platform. The detailed implementations of the providers with performance analysis are explained. I. Introduction In order to provide on demand QoS-guaranteed DiffServ-over-MPLS service provisioning across multiple autonomous system (AS) domain networks, the network management system (NMS) should be able to collect the information of inter-as connectivity and available network resources among autonomous system boundary router (ASBR) ports, and fault restoration capability of the traffic engineering label switched path (TE-LSP) [1]. For this end-to-end QoS-guaranteed DiffServ provisioning management, NMS must establish service level agreement (SLA) with other providers and with the customers. The NMS needs to interact with other NMSs of different network providers for the QoS-guaranteed TE-LSP connection This research was supported by the MIC, under the ITRC support program supervised by the IITA. Corresponding author.

2 establishment and this interaction is required to be platform and network resource independent. The managed objects (MOs) in inter-as traffic engineering should be standardized in public domain, thus can be easily accessible by other network providers. Currently, network management MOs for QoS-guaranteed DiffServ connection provisioning is not well standardized in public domain. Most currently available commercial IP/MPLS Systems are supporting simple network management protocol (SNMP) or command line interface (CLI) based management function without globally standardized MO definitions. As a result, it is not possible to easily collect the networking resource information of inter-as transit networks from other NMSs, negotiate the possible differentiated service provisioning on SLA negotiation, and establish and manage flexible TE-LSPs across multiple domain networks. Since web-based enterprise management (WBEM) and common information model (CIM) are platform and resource independent distributed management task force (DMTF) standard, they can provide a good framework for design and implementation of the MOs for inter-as traffic engineering [1]. WBEM defines both a common model (i.e., description) and protocol (i.e., interface) for monitoring and controlling resources from diverse sources (e.g., different types of platforms or different types of resources on the same platform). The inheritance and objectoriented design from CIM MOF (managed object format) can reduce development time, and also provide independence in platform and programming language [2]. The DMTF CIM MOFs are used as base classes for inter-operability among management systems that would be implemented by different network operators. The MOF design with inheritance enables simple implementation of new MOs for new management function with reusable common information of base MO, as the objectoriented design approach provides. Also, the polymorphism for easy networking enables easy access to new MO by remote manager who has limited knowledge on the actual implementation of inter-as traffic engineering MIB (management information base). Currently CIM has some experimental MPLS (multi-protocol label switching) and DiffServ (differentiated service) related MOFs, but detailed MOFs for QoS-guaranteed DiffServ provisioning are not available. We have designed MOs for SLA management, and inter-as TE-LSP connection management with several extensions on existing experimental DMTF CIM MOFs with inheritance. With WBEM architecture, we have designed and implemented SLA negotiation. We have used directory agent (DA) [3], a centralized repository for storing the details of NMSs and their corresponding service location information. In this paper, we explain the detailed implementation approaches of WBEM-based TE- LSP connection management and SLA negotiation across multiple domain networks using OpenPegasus [4], OpenSLP [3], and COPS (common open policy service) [5]. The rest of this paper is organized as follows. In section II, the related work on WBEM and service level subscriptions (SLS) management are briefly introduced. In section III, WBEM based architecture for TE-LSP connection establishment and SLA negotiation are explained. The DMTF CIM-based extended MOF design for SLS negotiation, connection establishment and necessary WBEM providers are explained in section IV. In section V, the performance analysis of WBEM-based architecture for connection establishment is explained. We finally conclude this paper in section VI.

3 II. Background 2.1 Web-Based Enterprise Management (WBEM) WBEM is a platform and resource independent DMTF standard that defines both a common model and protocol for monitoring and controlling resources from diverse sources. DMTF defines the CIM that defines the management information for system, networks, application and services, etc. CIM includes the description of a meta-language for describing data (i.e., CIM specification) and a description of the resources to be managed (i.e., CIM schema and vendor extensions). CIM-XML is a DMTF standard for WBEM communication protocol that uses the CIM specification and CIM schema for the representation of managed resources, defines the encoding of CIM data and operations into XML, and uses HTTP transport protocol for exchanging CIM-XML encoded requests and responses [2]. CIM MOF is the language defined by the DMTF for describing classes and instances. 2.2 Service Level Specification (SLS) Management The SLS is used to denote the technical characteristics of the service offered in the context of an SLA. The service technical characteristics refer to the provisioning aspects of the service, such as request, activation and delivery aspects from network perspectives. Non-technical service provisioning aspects such as billing and payment aspects, are not part of the SLS; they are part of the overall SLA. SLS forms the basis of the agreements between providers for traffic exchange in the Internet. SLS include SLS identification, scope (geographical/topological region), flow identification, traffic conformance, excess treatment, performance guarantees, schedule, etc. Our work draws from the SLS template specification work of the MESCAL SLS specification [6-8]. QoS-based services are offered on the basis of the SLAs, which set the terms and conditions on behalf of both providers and customers in providing and requested services, respectively. Before committing any connection establishment, SLA negotiation should have been made between the providers. There is a performance monitoring part, for each negotiated QoS parameters (such as delay, jitter, packet loss, and throughput), which is composed of (i) Measurement Period, (ii) Reporting, and (ii) Notification Threshold [7]. The performance management would perform monitoring the QoS parameters that had been negotiated in the SLA so as to check that whether SLA is violated or not. III. Architecture of WBEM-based SLA Management on multidomain networks 3.1 WBEM based SLA management functional architecture Fig.1 depicts the functional block of WBEM-based SLA management for inter-as TE-LSP connection establishment. The OpenSLP server acts as a dedicated

4 DA where all NMSs register and discover the service contact points using service location protocol (SLP). Each NMS is configured with OpenPegasus WBEM Server. OpenPegasus supports service agent (SA) functionality for service registration to DA. The API (application programming interface) for OpenPegasus client includes user agent (UA) functionality such as service lookup and request. The SLP provider has SA functionality for service registering and CIM client has UA functionality for service request. During the NMS s WBEM initialization, the SA in SLP provider tries to detect DA and then it registers itself to the DA. The service type has been defined as service:wbem.interas:pegasus. Once the service registration is successful, the UA can directly request service discovery to DA, and get information about interested service contact points. Fig. 1. WBEM-based SLA Negotiation Functional Block For SLA negotiation, we have designed the SLA Provider with COPS PDP and PEP functionalities. The Inter-ASQoSProvider is designed and implemented for the purpose of inter-as Traffic Engineering for QoS-guaranteed DiffServ-over-MPLS provisioning. SNMP Provider can interact with SNMP supported network element (NE) directly, using SNMP protocol. SNMP Trap Handler is included in SNMP Provider, and is used for fault detection mechanism by Fault Manager. 3.2 Interaction among NMSs for SLA management The interaction among the NMSs, DA and CNM (customer network manager) for SLA negotiation is shown in the Fig. 2 Before the interaction among NMSs is done, the NMS need to perform initialization of its providers. During NMS provider initialization, it tries to register itself to the DA, and to discover other NMSs that participate in inter-as TE from the DA using SLP protocol. Each NMS tries to gather the resource details from other NMSs to make inter-as topology

5 configuration. After the topology configuration is accomplished, SLA negotiation for inter-as TE can be handled. When on demand QoS-guaranteed TE-LSP connection request is made from any CNM, the ingress NMS performs constraint-based shortest path first (CSPF) routing. Then it makes SLA negotiation among the providers which manages the corresponding domains that are in the path to the destination. Once the ingress NMS receives successful decision from other providers for the negotiated parameters, it can make QoS enforcement in its domain, i.e., it can configure its managed resources for accommodating the traffic agreed on the negotiated SLA. All the service providers who agreed with the SLA will perform QoS enforcement on their managed domains. The data transfer can take place at the scheduled time mentioned as one of the SLA parameters during SLA negotiation. Fig. 2. Interaction sequence diagram for SLA negotiation in inter domain networks IV. Design & Implementation of CIM MOF-based MOs and providers for WBEM-based SLA Management 4.1 Extended CIM MOs for SLA Management Fig.3 depicts unified modeling language (UML) representation of CIM classes and associations designed for SLA negotiation and connection establishment in inter-

6 AS TE. Some classes are designed as abstract classes and other classes inherit from the super classes. The classes QoS_interASNet_SLASrv, QoS_InterDomain_SLS, and Qos_DiffServOver MPLS-InterDomain_SLS are designed for SLA negotiation between the NMSs. The SLS parameters such as scope, flow-id, traffic conformance, excess treatment (drop/remark/shape), performance guarantees (delay, jitter, loss, throughput), schedule (time, day, year etc.) and performance monitoring parameters are defined in the base class QoS_InterDomain_SLS. The class Qos_DiffServOverMPLS-Inter-Domain_SLS extends from QoS_InterDomain_SLS with TE parameters. For inter-as traffic engineering, we designed QoS_OAM_Service MO which acts as super class and the services such as QoS_interASNet_PMSrv, QoS_interASNet_FMSrv, QoS_interASNet_CMSrv for performance management, fault management and connection management respectively. The class QoS_interASNet_SLASrv has the SLA negotiation module with both customer and provider implementation. Fig. 3. DMTF CIM based MOF classes for SLA negotiation 4.2 Inter-AS QoS Provider Implementation The inter-as QoS provider which is shown in Fig.1, acts as core part of our WBEM architecture. This provider includes instance provider, association provider and method provider functions for inter-as TE (traffic engineering). When WBEM server is loaded, the Inter-AS QoS Provider gets service location list of other providers from SLP provider and configures the inter-as connectivity topology. When SLA is negotiated by the customer (or other providers) with requested parameters, it computes CSPF routing for the requested destination based on the up-

7 to-date inter-as topology details. When NMS needs to establish TE-LSP connection setup and backup path, the method provider starts to establish connection by interacting with SNMP provider or CLI Provider in the WBEM server. All the provider modules are implemented using C SLP provider Implementation SLP provider in NMS consists of a service agent, user agent and CIM client. When the WBEM server is loaded, the SLP provider registers Inter-AS supported WBEM Pegasus service to statically registered DA. SLP provider periodically sends unicast service request message to DA to get the service location list of registered NMSs. Using CIM SLP Template instances, the SLP provider stores the details of the registered NMSs. Fig. 4. Service Discovery by SLP Provider Fig.4 shows the SLP provider operation for service register and discovery. In our implementation, DA address is statically configured in the NMS s SLP provider. The DA is implemented in Linux platform using OpenSLP[3]. The UA functionalities are provided by the OpenPegasus client API. 4.4 SLA provider Implementation SLA provider is used to negotiate the SLA between the providers and the customers. Before establishing any data transfer for on-demand connection request, the providers and customers negotiate each other for the mutual agreement on the proposed parameters in the SLS. The SLA negotiation between the providers and customers are implemented using the WBEM CIM model. Fig.2 explains the SLA negotiation process between the customers and the providers. The client initiates the negotiation by SLA_Open() to the provider. The SLA provider accepts the negotiation session by SLA_Accept(). When the client sends the SLA_Request() with the required parameters for on-demand TE-LSP connection provisioning, the

8 SLP provider checks whether the managed domain has enough resource for the new connection. This is done by calling getteinfo(), which in-turn calls getuptodatelocalstateinfo() method of Inter-AS QoS provider. The current network resources are checked and if the managed domain has enough resource, the service level negotiator will initiate the service level negotiations to other SLP providers who are in the route to the destination. If there is not sufficient resources available, the SLP provider can re-negotiate to the requested parties by calling SLA_Decision() request with re-negotiation option. Once the ingress NMS receives successful SLA_Decision() from all the NMSs, they can enforce the NE configuration by using SNMP provider or CLI provider. The ingress NMS calls the customer with the decision by SLA_Desicion(). The decision could be either accept/reject or renegotiate. The customer can send the report by SLA_Report() to the ingress-nms, which conveys that the customers decision to the provider about the negotiation. V. Performance evaluations on SLA negotiation for TE-LSP connection establishment in inter-domain networks In our current implementation with OpenPegasus based WBEM architecture for SLA negotiation in 5 AS domain networks (as shown in Fig. 2), the overall negotiation time among the providers takes around 6~8 seconds. On the average it takes around 1.8 sec for successful provider-to-provider negotiation. 5.1 SLA negotiation for TE-LSP connection establishment Fig. 5 shows time taken by the SLA negotiation process with five NMS. When the ingress NMS gets a request for SLA negotiation for TE-LSP connection establishment, it checks itself with getteinfo(). The request will perform association traversals and instance enumerations on the repository. The graph depicts the time taken for enumerating the instances the CIMOM repository Time (sec) Number of Instances Fig. 5. SLA negotiation request processing From the graph, it is clear that there is not much variance in time taken and the time taken is irrespective to the number of instances enumerated. On the average, it takes almost 1.78 seconds. It shows the better scalability for the number of instances

9 to be enumerated. The ingress SLA provider will interact with other four NMSs SLA providers sequentially and the cumulative time taken is around 6~8 sec for end-toend negotiation. 5.2 Performance measurements for all activities in End-to-End SLA negotiation Fig. 6 shows the complete time taken by each functions of WBEM architecture involved for SLA negotiation for TE-LSP connection establishment in inter-domain networks. The service discovery using SLP protocol took around 7 ms and the CSPF computation for the given topology with five NMS took around In general the method invocation such as SLA_Open(), SLA_Report(), and SLA_Decision() take few milliseconds (30~40 ms). Time (ms) Service Discovery CSPF Routing SLA Negotiation - Method Invocation 1782 Association Traversals Fig. 6. Complete SLA negotiation activities From the performance analysis, we found that the instance creation time depends on the hardware specification and method invocation does not take much time. The Provider API function for association traversals and enumerating instances also does not take much time. We are developing multi-thread based parallelism in implementation to improve the overall performance. VI. Conclusions In this paper, we designed MOs for SLA negotiation for inter-as TE-LSP connection establishment with extensions on existing experimental DMTF CIM MOFs with hierarchical inheritance. We designed MOs to represent SLA negotiations, service registration/discovery, interasnet & QoSDiffServNet. We also designed MOs related to interasnet OAM functions, such as connection management, performance monitoring and fault management. The interaction scenario among DA, NMSs with WBEM server/client function of different AS domain networks for SLA negotiations and inter-as TE are explained. The SLA negotiation is done by using COPS protocol. Currently we are

10 implementing the providers illustrated in the proposed inter-as traffic engineering system based on OpenPegasus WBEM. The implementation is done on Linux based OpenPegasus WBEM. From the performance analysis, the overall time taken for SLA negotiation for TE-LSP connection establishment between the provider and the customer is around 1.7~2 seconds. Currently we are doing the detailed performance analysis. From the result of the analysis and the standardized WBEM based architecture, we can conclude that WBEM-based SLA negotiation architecture for inter-as traffic engineering can be successfully applied for inter-as QoS-guaranteed DiffServ-over-MPLS connection provisioning. References 1. Young-Tak Kim, Inter-AS Session & Connection Management for QoSguaranteed DiffServ Provisioning, Proc. of International Conference on Software Engineering Research, Management & Applications (SERA 2005), Mt. Pleasant, USA, pp. 325~ Web-based Enterprise Management (WBEM), 3. OpenSLP, 4. OpenPegasus, 5. T.M.T. Nguyen, N. Boukhatem, G. Pujolle, "COPS-SLS Usage for Dynamic Policy-based QoS Management over Heterogeneous IP Networks", IEEE Network, May/June SLS Management, 7. Goderis, D. et al., Service Level Specification Semantics and Parameters, Internet Draft, <draft-tequila-sls-02.txt>, January Dong-Jin Shin, Young-Tak Kim "Design and Implementation of Performance Management for the DiffServ-aware-MPLS Network," Proceedings of Conference on APNOMS 2003, Fukuoka, Japan, October Shanmugham Sundaram, Abdurakhmon Abdurakhmanov, Young-Tak Kim, "WBEM-based Inter-AS Traffic Engineering for QoS-guaranteed DiffServ Provisioning," IEEE Broadband Convergence Networks (BcN2006) Workshop, Vancouver, British Columbia, Canada, 2006.