System Architecture Design

pSHIELDSystem Architecture DesignPUFigure 7 - Cross-layer architectures for indirect and direct communications.The first category, direct communications, should be used when only a single cross layer optimization isplanned. The second category, indirect communications, is realized with a common cross-layer entity orcross-layer manager, which acts as a mediator between the layers. The cross-layer entity includes anetwork status component of the stack that interfaces the different layers between themselves and acts asa database where each network layer can put or get information. This architecture should be used formultiple cross layer optimizations.3.1.3 The Overlay as a Cross-Layer Security Architecture for Security, Privacy andDependabilityAs we have seen in the previous section, a Cross-Layer Architecture is a design paradigm that couldimprove the performance of a generic system by simply allowing information exchange among the layers.This approach has been widely described for Telecommunication environment, however for the purposeof the pSHIELD project we need to adapt it to a different context by addressing two main issues:i) while classical Cross-Layer is applied to the seven, well known, ISO/OSI layers, pSHIELD Cross-Layeris applied to three heterogeneous and complex layers named Node (the hardware), Network (theinterconnection between nodes) and Middleware (the software services located between the hardwareand the applications providing the core SPD functionalities)ii) while classical Cross-Layer aims at optimizing telecommunication quality of service performances (likebandwidth, transmission delays and so on), the pSHIELD Cross-Layer is in charge of addressing Security,Privacy and Dependability to bring them to a reference, desired value. With Security, Privacy andDependability we refer to a wide set of functionalities relevant for the system like Authentication,PUD2.3.2Issue 5 Page 26 of 122