Jorge E. López de Vergara

Ontology-Based Network Management: Study Cases and Lessons Learned

Ontology based network management has recently evolved from a theoretical proposal to a more mature technology. As such, it is now being applied in many research projects in a number of different network management and security scenarios. This application has enabled the validation of the main ideas of the proposals and to learn some of the problems that it brings. This paper describes several research projects where ontology based network management proposals were applied, detailing the most important facets of the initial proposals that were used and explaining the main advantages and drawbacks that were found after prototyping these proposals.

Ontology-based policy refinement using SWRL rules for management information definitions in OWL

The goal of ontology-based management is to improve the manageability of network resources through the application of formal ontologies. Prior research work has studied their application to represent the management information definitions, the mapping and merging processes to obtain a semantic integration of those definitions, and the representation of behaviour and policy definitions. Using ontologies allows the additional advantage of integrating, in the same semantic manager, business and service level ontologies with the network management ontology, in a framework for automated management. This integration allows for policy refinement and interoperation between high level policies and low level policies.

Ontology-Based integration of management behaviour and information definitions using SWRL and OWL

Current network management architectures are using different models to define management information objects. These definitions actually also include, in a non-formal way, the definition of some behaviour information that a manager should accomplish related to the managed objects. So, a manager is not able to make an automatic processing of this behaviour information. Prior research work proposed the use of formal ontology languages, such as OWL, as a way to make a semantic integration of different management information definitions. This paper goes further proposing a formal definition of the different management behaviour specifications integrated with the management information definitions. Thus, usual behaviour definitions included implicitly in the management information definitions and explicitly in policy definitions can be expressed formally, and included with the information definitions. This paper focuses on the definition of behaviour rules in management information with SWRL, a rule language defined to complement OWL functionality.

On the analysis of burst-assembly delay in OBS networks and applications in delay-based service differentiation

In Optical Burst Switching (OBS), packets travel through the network core as part of longer-size optical bursts, which do not suffer electronic conversion until they reach an eggress point. Typically, such optical bursts comprise tens or hundreds of packets, which are assembled/deassembled at border nodes. During the burst-formation process, each arriving packet must wait until the final burst is complete, which clearly adds an extra delay on each packet in the burst, especially on those arriving earlier. However, such burst-assembly delay may be excessive for the appropriate performance of certain applications, mainly real-time interactive ones. This work’s findings are twofold: first, it characterises the burst-assembly delay distribution of each packet in a burst arisen by the main assembly algorithms found in the literature; and, second, it introduces a new burst-assembly strategy that takes into account the particular delay constrains of packets in the formation of optical bursts, along with a detailed study of its properties.

Application of OWL-S to define management interfaces based on web services

Some network management trends are currently analysing the application of several generic technologies that include Web Services and Ontologies. Web Services can provide an interface to access to managed resources. On the other hand, ontologies provide a way to represent management information. Web Services interfaces can be defined using OWL-S, an ontology of services that semantically describes the set of operations a Web Service provides. This can be useful in configuration management, where each network resource defines the way it can be configured. This paper presents a proposal to describe with the OWL Service ontology the management interfaces based on Web Services. To illustrate this approach, an example is provided in which OWL-S is used to specify the processes needed to configure a resource.

Bridging the gap between hardware and software open source network developments

The rise of network speeds to tens of gigabits per second poses a challenge to develop packet processing applications that can cope with such bit rates. Therefore, the need for a suitable open source system that can be used as a prototype platform to test new network functionality while ensuring line-rate processing, accurate timestamping, and reduced power consumption has become evident. All these requirements cannot be achieved by using software-only solutions, but rather with hardware-based platforms such as NetFPGA. The main obstacle when using this type of open source FPGA-based solution is the cost of development, in both time and hardware development skills required. The spread of new circuit synthesis tools using high-level languages opens the door for the development of hardware-based networking applications with reasonable development effort, compared to the use of traditional hardware description languages. In this article, we describe how existing open source hardware-based platforms for networking applications will be fueled by the change in the programming model of FPGAs provided by modern high-level synthesis tools. For this, we implemented a network flow monitor using high-level languages and compared the effort spent with respect to a traditional hardware development cycle. Preliminary results are very promising, given that development time is reduced from months to weeks.

Benefits of Using Ontologies in the Management of High Speed Networks

Network management is an area where many different technologies coexist. Several languages are used to define the information to be managed, which are specific of each management model. As a result, many specifications that describe similar resources are expressed separately. To solve this question, this paper takes advantage of the knowledge representation technique known as ontology to unify current heterogeneous information definitions from a semantic viewpoint. With this approach, management information is specified using ontology languages, including behavior constraints, and methods used to combine ontologies are applied to merge and map the concepts contained in existing management models.

Utilization of temporary reservation of path computed resources for multi-domain path computation element protocols in WDM networks

In recent years, Path Computation Element (PCE) architecture has been standardized as a suitable solution for path computation in multi-domain network scenarios. The Traffic Engineering Database (TED) of the PCE is updated with the information of the control plane. However, there is a delay from the PCE replies to a request, until the TED is updated with the network status information. This delay includes not only the control plane delay, but also Path Computation Element Protocol (PCEP) information exchange. This desynchronization in the TED and the real status information leads to an extra blocking situation when the Label Switch Router (LSR) tries to reserve a path, but it has been previously reserved by other LSR. To solve such problem, a recent draft is submitted to the IETF proposing new PCEP extensions for a pre-reservation of the computed path resources for a certain period. This work implements in C three multi-domain algorithms: Per-domain Path Computation, Backward-Recursive PCE-based Computation and Hierarchical Path Computation Element and it assesses their performance with and without mechanisms to reduce this extra blocking probability due to the uncertainty of the TED information.

Extending SWRL to enhance mathematical support

This paper presents an extension to the Semantic Web Rule Language and a methodology to enable advanced mathematical support in SWRL rules. This solution separates mathematical and problem semantics allowing the inclusion of integration, differentiation and other operations not built-in to SWRL. Using this approach, it is possible to create rules to cope with complex scenarios that include mathematical relationships and formulas that exceed the SWRL capabilities.

An ontology-based approach to the description and execution of composite network management processes for network monitoring

Web service technology has been proposed to implement management interfaces of managed resources. These web services can usually be combined to perform composite processes. These composite processes can be defined with service ontologies such as OWL-S, which allows their formal description. However, other technologies, including the Web Services Business Process Execution Language (WSBPEL), provide more mature execution engines. This paper presents an approach to define and execute composite network management processes with existing technology. For this, a use case is developed in which a set of web service interfaces are defined for a network probe, and a composite process is specified using OWL-S to monitor the network load. Then, this specification is later translated to WSBPEL and interpreted by a real execution engine.