Branch-Awareness in Service Function Graph Design and Embedding

To deliver an end-to-end service in the Network Function Virtualization (NFV) environment, Service Function Chain (SFC) is used to define the sequence of Virtual Network Functions (VNFs) that needs to be applied to the data stream of the service. In the literature, SFC is typically regarded as a linear topology that represents the sequence of the VNFs that a data stream is navigated through. Our recent study, however, reveals a group of real-life use cases for which a linear topology is in-sufficient to describe the complexity of the SFC: the data stream can branch out into multiple streams due to multiple reasons (e.g., load-balance the web/non-web traffic). In this paper, we study representative use cases with presence of branching, categorize traffic branching into three major categories, and introduce policies to specify the service requirement that involves traffic branching. In addition, we define the resulting problem and discuss directions for further exploration.