Service Function Chaining (SFC) Parallelism and Diversions

Service Function Chaining (SFC) is the processing of packets through a sequence of Service Functions (SFs) within an SFC domain by the addition of path information and metadata on entry to that domain, the use and modification of that path information and metadata to step the packet through a sequence of SFs, and the removal of that path information and metadata on exit from that domain. The IETF has standardized a method for SFC using the Network Service Header specified in RFC 8300. There are requirements for SFC to process packets through parallel sequences of service functions, rejoining thereafter, and to easily splice in additional service functions or splice service functions out of a service chain. The IETF has received a liaison from International Telecommunication Union (ITU) indicating their interest in such requirements. This document provides use cases and specifies extensions to SFC to support these requirements.