Fog computing brings the cloud closer to a user with the help of a micro data center (mdc), leading to lower response times for delay sensitive applications. RT-SANE (Real-Time Security Aware scheduling on the Network Edge) supports batch and interactive applications, taking account of their deadline and security constraints. RT-SANE chooses between an mdc (in proximity to a user) and a cloud data center (cdc) by taking account of network delay and security tags. Jobs submitted by a user are tagged as: private, semi-private and public, and mdcs and cdcs are classified as: trusted, semi-trusted and untrusted. RT-SANE executes private jobs on a user's local mdcs or pre-trusted cdcs, and semi-private and public jobs on remote mdcs and cdcs. A security and performance-aware distributed orchestration architecture and protocol is made use of in RT-SANE. For evaluation, workload traces from the CERIT-SC Cloud system are used. The effect of slow executing straggler jobs on the Fog framework are also considered, involving migration of such jobs. Experiments reveal that RT-SANE offers a higher "success ratio" (successfully completed jobs) to comparable algorithms, including consideration of security tags. Index Terms-Fog computing, mobile data center, cloud data center, security aware services, real-time systems.