A Reliability Study of Parallelized VNF Chaining

TL;DR

This paper analyzes how parallelizing service function chains and flow splitting in data center networks enhances reliability and reduces backup requirements, providing an analytical framework for optimal placement and reliability assessment.

Contribution

It introduces a novel analytical model for evaluating reliability of parallelized SFCs considering failures, and demonstrates how parallelism improves reliability and reduces backup needs.

Findings

Parallel SFCs significantly increase end-to-end reliability.

Flow and SFC parallelism reduce the number of backup VNFs needed.

Analytical models accurately predict service success probability.

Abstract

In this paper, we study end-to-end service reliability in Data Center Networks (DCN) with flow and Service Function Chains (SFCs) parallelism. In our approach, we consider large flows to i) be split into multiple parallel smaller sub-flows; ii) SFC along with their VNFs are replicated into at least as many VNF instances as there are sub-flows, resulting in parallel sub-SFCs; and iii) all sub-flows are distributed over multiple shortest paths and processed in parallel by parallel sub-SFCs. We study service reliability as a function of flow and SFC parallelism and placement of parallel active and backup sub-SFCs within DCN. Based on the probability theory and by considering both server and VNF failures, we analytically derive for each studied VNF placement method the probability that all sub-flows can be successfully processed by the parallelized SFC without service interruption. We evaluate the amount of backup VNFs required to protect the parallelized SFC with a certain level of service reliability. The results show that the proposed flow and SFC parallelism in DCN can significantly increase end-to-end service reliability, while reducing the amount of backup VNFs required, as compared to traditional SFCs with serial traffic flows.