ACHO: a framework for flexible re-orchestration of virtual network functions

Abstract

Network Function Virtualization enables network slicing as a novel paradigmfor service provisioning. With network slicing, Virtual Network Functions(VNFs) can be instantiated at different locations of the infrastructure, choosing their optimal placement based on parameters such as the requirementsof the service or the resources available. One limitation of state-of-the-arttechnology for network slicing is the inability to re-evaluate orchestration decisions once the slice has been deployed, in case of changing service demandsor network conditions.In this paper, we present ACHO, a novel software framework that enablesseamless re-orchestration of VNFs of any kind, including RAN and Core.With ACHO, VNFs and resources can be easily re-assigned to match, e.g.,varying user demands or changes in the nodes' load. ACHO uses lightweightmechanisms, such as splitting the engine of a VNF from the data it requiresto perform its operation, in such a way that, when re-allocating a VNF, onlythe data is moved (a new engine is instantiated in the new location). Wedemonstrate the use of ACHO in a small scale testbed, showing that (i) theproposed re-orchestration is feasible, (ii) it results much faster than existingalternatives (especially for relocation), and (iii) the framework can be readilyapplied to existing VNFs after minimal changes to their implementation.