Todays NoCs are reaching a level where it is getting very hard to ensure 100% of functionality. Consequently, fault tolerance has become an important aspect in todays design techniques and like the system itself, it has to be validated and tested. A vulnerable point of attack for faults in distribiuted systems like NoCs is certainly the interconnect. In this paper, we will give an overview about todays challenges in interconnect technology and potential resulting physical faults. Unfortunately, describing faults on the physical level oo accurate and so it is necessary to abstract and to map all these faults to a logical level. In more complex systems, also the logical level may become too detailed. As a an even more abstract layer, which is defined as the functional level, has to be introduced. To be able to verify fault tolerance, an experiment based test approach like fault injection is necessary. Arrow is a generic hardware fault injection tool, written in the hardware description ...