D-2.3.1 Final Architectural Framework

The deliverable D-2.3.1 Final Architectural Framework is available for review and comment.
The 4WARD WP2 main objective is the development of an Architecture Framework to represent and design future network architectures within families of interoperable networks. The developed set of solutions, concepts, and procedures can be used to model current networks, 4WARD networking solutions and future networks.
This Architecture Framework comprises architectural concepts as well as a Design Process. With respect to the architectural concepts we followed a macroscopic view on network architectures as well as a microscopic view in order to develop the basic constructs of the Architecture Framework. The macroscopic view introduces the concept of Strata as a flexible way to layer the services of the network that inherently supports cross-layer information exchange. The microscopic view concentrates more on the functions needed within a network node in a certain network architecture. These functions are encapsulated in so-called Netlets. The Node Architecture provides a generic framework for Netlets. It can flexibly host Netlets, which possibly belong to different network architectures. Within the Node Architecture, Netlets are considered as black-boxes that provide a certain service and that can be exchanged on- the-fly if needed.
This document, D2.3.1, focuses on the work provided during the last six months of the project. Both deliverables together, i.e. D2.3.0 and D2.3.1 describe the Architecture Framework developed within the 4WARD project and provide evaluation results. The focus during the last six months of the project was mainly on two directions:
Complementing the Architecture Framework with a focus on the Design Process and the Design Repository
Evaluation of selected parts of the Architecture Framework
Since this deliverable concentrates on the work performed during 2010, i.e., during the last period of the project, it naturally has some focus on evaluation. Additionally, the basic constructs and concepts have been complemented with further details. Clearly, main focus was on the Design Process, especially the Design Repository and examples for Design Patterns. In the following, an overview of the complements and conclusions is given.
The strata concept (i.e., the macroscopic view) eases cross-layer information exchange, especially due to the availability of vertical strata. Additionally, it provides an increased flexibility since it avoids strictly hierarchical layering. Prototyping activities around the CBA- based prototype can be seen as a feasibility proof of the strata concept.
The Node Architecture (i.e., the microscopic view) should be seen as a framework for a network node that runs multiple network architectures concurrently. It could be shown that Netlets can be exchanged on the fly and that the selection process of a suited Netlet does not become a bottleneck. Example Netlets for end systems and intermediate nodes are presented, reflecting the advantages of the flexible composition approach. In order to support dynamic configuration of network architectures, some alternatives regarding the associated signalling and negotiation are discussed. Various demonstrators and prototype implementations have underlined the practicability of the concepts around the Node Architecture and the Netlets.
Considering the Design Process a major focus was on the Design Repository during this phase of the project. It promotes reusability and avoids that the Network Architect reinvents the wheel every time a new network architecture is being designed. It contains, for example, the basic constructs (Strata, Netlets), Design Patterns, and software components. Security aspects related to the Design Repository are discussed. The security built into the Design Repository is closely related to how it will be used.
Three Design Patterns were developed: The Interdomain Interface, the Association and Composition of Functionalities. With the Interdomain Interface, a minimal implementation of the SGP (Strata Gatewaying Point) is provided that is to be implemented at all interconnection points between domains. The Association provides support for proper modelling of a variety of communication paradigms. Furthermore, the Composition of Functionalities describes a way on how a Network Architect can compose functionalities, in addition to the application of SOA- based concepts to the composition of functionalities.
The second part of this deliverable documents the validation and implementation work in this last working period. Different methods have been applied for evaluation and validation purposes: use cases, modelling, simulation experiments, and prototyping (including demonstrators).
The Design Process has been validated through the application of a use case related to an AdHoc Community. Different types of requirements (business requirements and technical requirements) are derived as first steps, followed by the identification of network functionalities at the macroscopic level (i.e., strata) and, along with this, the logical nodes. Then Netlets are identified. In order to derive an implementation of the designed network architecture, the software components are then selected, combined and, eventually, deployed. This validation effort has underlined the general usefulness of the Design Process and its applicability. Further support by appropriate tools, however, will be needed for practical applications. The Netlet Editor developed earlier within the project can serve as a simple example for that since it provides some support for the design and evaluation of Netlets. The same holds for the Acme-based modelling activities as described in the following.
A formal model of the network architecture from a macroscopic point of view is provided in addition to a model from a microscopic point of view that has been developed earlier in the project. The modelling was done in Acme. Armani predicate rules were applied to validate the correctness of the modelled scenario. It could be shown that this way of modelling network architectures supports the Network Architect during the design of a network architecture. The validity of the scenario as well as the fulfilment of properties can be proven.
The practicability of the selected concepts of the Architecture Framework was mainly validated through prototyping activities that also resulted in different demonstrators. These demonstrators were presented at the project review in Aachen in 2010.
• Integrated WP2/WP4 demonstrator:
This demonstrator integrates concepts of In-Network Management (WP4) with basic constructs (Strata, Component-Based Architecture) of the Architecture Framework. Easy deployment of networks, real-time monitoring and self-adaptation within network domains were demonstrated. Another important issue was on the interoperability between different network domains based on the strata SGPs (Strata Gatewaying Points).
• Integrated WP2/WP3 demonstrator:
This demonstrator integrates virtual networks (WP3) with basic constructs (Node Architecture, Netlets) of the Architecture Framework. It shows the design and test of Netlets as well as the deployment of the Node Architecture (including Netlets) into a virtual network. Dynamic adaptations of Netlets as well as the virtual network were successfully demonstrated.
Both prototypes, the CBA-based prototype as well as the Node Architecture prototype, were enhanced during the last period of the project.
• The CBA-based prototype was extended with an implementation of the Association Design Pattern as well as with a sequence to elaborate on a novel name resolution and routing scheme.
The Node Architecture prototype was extended with Routing Netlets (AODV-based, OLSR-based) supporting different types of mobile ad hoc networks (MANETs) with individually suited routing services. Additionally, a protocol for dynamically switching between these Routing Netlets as reaction to changes in the networking situation has been designed and implemented. Regarding the Node Architecture it could be shown that both, fine tuning of parameters as well as dynamic switching of similar Netlets is supported. Generally, this underlines the flexibility and extensibility of the Node Architecture.
The switching protocol was tested and evaluated in a simulation environment. It could be shown that the proper parameter tuning improves the convergence time, as expected.
• The Node Architecture prototype was further extended with QoS blocks. The validity of the implementation was tested through network measurements.
Furthermore, signalling in multi-access networks has been designed and incorporated into the integrated macroscopic/microscopic view and investigated through simulation experiments.
• Two tuning/optimization algorithms have been developed to optimize the packets size for WLAN transmissions. It could be shown that throughputs with controlled packets size are significantly higher than with fixed packets sizes. The number of concurrent users in WLANs can be increased.
• The selection of the network interface within a multi-access network was also investigated. Based on the proper interface selection, delay and throughput can be improved.