Specifying and Placing Chains of Virtual Network Functions

TL;DR

This paper introduces a formal model for chaining virtual network functions using context-free languages, and presents an optimization approach for their placement considering resource constraints and trade-offs.

Contribution

It proposes a formal language-based model for virtual network function chaining and a MIQCP-based method for optimal placement considering resource limitations.

Findings

Developed a context-free language model for network function chaining.

Formulated the placement problem as a MIQCP.

Performed Pareto analysis to explore trade-offs.

Abstract

Network appliances perform different functions on network flows and constitute an important part of an operator's network. Normally, a set of chained network functions process network flows. Following the trend of virtualization of networks, virtualization of the network functions has also become a topic of interest. We define a model for formalizing the chaining of network functions using a context-free language. We process deployment requests and construct virtual network function graphs that can be mapped to the network. We describe the mapping as a Mixed Integer Quadratically Constrained Program (MIQCP) for finding the placement of the network functions and chaining them together considering the limited network resources and requirements of the functions. We have performed a Pareto set analysis to investigate the possible trade-offs between different optimization objectives.