rt-networking

Recent development in RTLinux have focused on extending the realtime capabilities of RTLinux beyond the single node UP and SMP system to distributed RT-systems that utilize commodity component computers network hardware. These realtime networking efforts have now been merged into the embedded RTLinux allowing to extent realtime constraints over networking infrastructure. Distributing computational resources, which is very demanding on the networking layer, can be extended with realtime capabilities becoming available. Basically this allows to reduce the locality of resources which improves the flexibility of embedded systems and opens new possibilities in embedded system design. With realtime networking available for embedded RTLinux it is possible to tightly synchronize nodes and offer statically allocated channels between embedded RTLinux nodes pushing QOS effort all the way to hard-realtime. Current implementations are still limited with respect to security provisions (no encryption/authentication for realtime networking) but conceptual work in this are is under way. It might be noted here that the question of security in realtime networks has generally been neglected and (all ?) implementations simply assume they will operate in a 'secure' environment.

FSMLabs hard realtime network, lnet, intercepts the network connections passing all received data to a realtime handler, packets destined for non-realtime services managed by the general purpose OS (Linux) will be passed on when system resources are available (that is when no realtime task is ready to run). This concept of RTLinux hard realtime networking allows providing RT-networking over the same physical link that is used for the general purpose OS net-link. As Linux has all provisions for multi-homed systems providing a dedicated realtime link is simple. The decision if a dedicated link or a shared link is to be used is thus based on bandwidth and timing demands only.