Multihoming Aware Optimization Mechanism
Authors
Abstract
THE always best connected paradigm has gain a lot o finterest in the research and scientific community. The availability of different wireless technologies and the proliferation of devices supporting multiple connections are open- ing new possibilities for users to share information everywhere and everytime. The multihoming support is being enriched to levels never before established. Indeed, users can configure devices to meet their own requirements, decrease communication costs by choosing links with no expenses associated, or opting for links that provide extended coverage. Such kind of configuration is often limited to static policies that aim the maximization of a single requirement, such as monetary cost or coverage. This approach is not efficient. For instance, if the optimization aims to decrease cost, extend coverage and increase security support simultaneously, static policies do not scale and have narrow support for multihoming goals, namely resilience, ubiquity and load sharing.Multihoming is an important aspect in computer networks. To enable higher lev- els of availability or optimize recovery processes in the presence of failures are goals that mechanisms improving resilience aim to support. Other goals, in a ubiquity as- pect, can include networks providing extended coverage but with minimized costs. To successfully achieve such goals and others, multihoming must be considered from the early phases of Internet architectures development. The choice of protocols and technologies with the best multihoming support is an important step to conceive net- work architectures that are multihoming efficient. With this concern in mind, this the- sis introduces the specification of resilience and ubiquity frameworks that assess the support of resilience and ubiquity goals in protocols. These evaluation frameworks provide a taxonomy that fully characterize multihoming goals.
Efficient multihoming support requires the optimization of multiple criteria com- prising diverse goals. This NP-hard problem considers benefits criteria providing profit and costs criteria introducing some kind of overhead. Techniques like Mul- tiple Attribute Decision Mechanism (MADM) provide ideal solutions for such kind of optimization problems, as they are not tied to a specific number of criteria. Even though, previously defined MADM techniques include criteria preferences, they do
not specify how these preferences can be expressed in objective and consistent ways. In addition, they can introduce side-effects, such as unnecessary handovers. Bear- ing with these issues in mind, this work introduces MeTHODICAL, an optimization technique that provides a complete solution for optimization within the multihoming context.
By introducing a complete optimization technique that determines optimal paths according to multihoming support, in this thesis, paths providing a better benefit/- cost ratio are selected. The introduced optimization technique includes a weighting algorithm that allows users to specify criteria preferences objectively and coherently. Moreover, MeTHODICAL addresses the NP-hard problem by specifying a technique that includes a decision stability factor to avoid side-effects and can be deployed in any scenario irrespective of the number of possible connections. The optimization tech- nique organizes hierarchically the different multihoming criteria according to their type (e.g. benefits or costs) and for each communication path. Standard measurement mechanisms are applied to determine values of the diverse multihoming criteria, as specified in the proposed resilience and ubiquity evaluation frameworks. As values of diverse criteria are collected, they are normalized and combined with the respective preferences. Ideal solutions are determined based on maximum benefits and mini- mum costs values. The distance of benefits and costs criteria of each path establishes how far a path is to the ideal solution. The path with lower benefits and costs distance is the one providing a better multihoming experience.
The performance of MeTHODICAL has been extensively analysed in different evaluation scenarios with multiple types of applications and employing diverse eval- uation metrics. Results demonstrate that MeTHODICAL improves multihoming sup- port, by choosing paths with the best benefit/cost ratio. The evaluation results also demonstrate an increase in path selection stability, and for VoIP applications, an in- crease in VoIP quality, outperforming related approaches. These results highlight that multihoming experience on end-devices can meet user expectations by employing Me- THODICAL, an efficient optimization mechanism with low computational complex- ity.