Specification of Complex Structures in Distributed Service Function Chaining Using a YANG Data Model

While services benefit from distributed cloud centers running in isolation, allowing multiple centers to cooperate on implementing services unlocks the full power of distributed cloud computing. Distributed cloud services are typically set up by chaining together a number of functions that are specified with an implicit order. They can incorporate complex structures, e.g., include functions that classify and forward flows over distinct branches and functions that are traversed by certain types of flows but skipped by others. These requirements need specification techniques more powerful than existing graph-based ones. We present a context-free grammar for abstract description of service function chaining structures and a concrete syntax based on the YANG data modeling language that can easily be translated into an explicit configuration of service functions. Finally, we present examples of using our models for complex services within common use cases of service function chaining.