On Coding for Reliable VNF Chaining in DCNs

TL;DR

This paper explores how erasure coding can enhance reliability in Data Center Networks by deploying parallel sub-flows, encoding, and distributed processing of Virtual Network Functions, leading to improved service resilience and reduced overhead.

Contribution

It introduces a novel coding-based scheme for VNF chaining in DCNs, demonstrating improved reliability and lower overhead compared to traditional backup methods.

Findings

Coding improves service reliability in DCNs.

Proposed scheme reduces overhead compared to backup protection.

Analytical model quantifies success probability of coded sub-flows.

Abstract

We study how erasure coding can improve service reliability in Data Center Networks (DCN). To this end, we find that coding can be best deployed in systems, where i) traffic is split into multiple parallel sub-flows, ii) each sub-flow is encoded; iii) SFC along with their corresponding Virtual Network Functions (VNF) concatenated are replicated into at least as many VNF instances as there are sub-flows, resulting in parallel sub- SFCs; and iv) all coded sub-flows are distributed over parallel paths and processed in parallel. We study service reliability as function of the level of parallelization within DCN and the resulting amount of redundancy. Based on the probability theory and by considering failures of path segments, VNF and server failures, we analytically derive the probability that parallel subflows are successfully processed by the parallelized SFC and that the original serial traffic can be successfully recovered without service interruptions.We compare the proposed failure protection with coding and the standard backup protection and evaluate the related overhead of both methods, including decoding, traffic redirection and VNF migration. The results not only show the benefit of our scheme for reliability, but also a reduced overhead required in comparison to backup protection.