DE GRUYTER OLDENBOURG it – Information Technology 2015; 57(5): 267–276 Special Issue Wouter Tavernier*, Bram Naudts, Didier Colle, Mario Pickavet, and Sofie Verbrugge Can open-source projects (re-)shape the SDN/NFV-driven telecommunication market? DOI 10.1515/itit-2015-0026 ACM CCS: Networks → Network services → Programmable Received June 30, 2015; revised July 17, 2015; accepted July 20, 2015 networks Abstract: Telecom network operators face rapidly chang- ing business needs. Due to their dependence on long prod- uct cycles they lack the ability to quickly respond to chang- 1 Introduction ing user demands. To spur innovation and stay competi- tive, network operators are investigating technological so- The increased softwarization and programmability have lutions with a proven track record in other application do- changed the telecom landscape significantly. Whereas mains such as open source software projects. Open source communication networks previously were under the rigid software enables parties to learn, use, or contribute to control of vendor-specific solutions or tightly standardized technology from which they were previously excluded. protocols, Software-Defined Networking (SDN) enabled OSS has reshaped many application areas including the network operators to configure the control of their net- landscape of operating systems and consumer software. works through their-own custom software. Network Func- The paradigm shift in telecommunication systems towards tion Virtualization (NFV) pushes this even further by mak- Software-Defined Networking introduces possibilities to ing it possible to code data plane behavior in software, en- benefit from open source projects. Implementing the con- abling it to run on general purpose server hardware rather trol part of networks in software enables speedier adap- than on expensive vendor-controlled hardware platforms. tion and innovation, and less dependencies on legacy This openness and control provides unseen perspec- protocols or algorithms hard-coded in the control part of tive in avoiding vendor-based monopolies or vendor lock- network devices. The recently proposed concept of Net- in for network providers and operators. However, if not work Function Virtualization pushes the softwarization steered carefully, a new threat could be that the software- of telecommunication functionalities even further down driven telecom landscape might again fall into the hands to the data plane. Within the NFV paradigm, functional- of a limited number of players with strong software skills ity which was previously reserved for dedicated hardware and/or departments. A similar situation occurred in the implementations can now be implemented in software domain of operating system software for pcs, which was and deployed on generic Commercial Off-The Shelf (COTS) dominated for years by a few big players such as Microsoft hardware. This paper provides an overview of existing or Apple. The introduction of open source (OS) software open source initiatives for SDN/NFV-based network archi- (OSS) projects, however has made the OSS market more tectures, involving infrastructure to orchestration-related democratic and innovative, enabling billions of end-users functionality. It situates them in a business process con- to use, extend and research, for example Linux-based OSes text and identifies the pros and cons for the market ingen- for professional, research or educative purposes. Through eral, as well as for individual actors. the increasing importance of software, similar conditions and opportunities might arise for OSS in telecom net- Keywords: Software-Defined Networking, Network Func- works. tion Virtualization, open-source software. The goal of this paper is to clarify the role of existing and potential open source projects within this context of SDN and NFV-driven communication networks. We will in- *Corresponding author: Wouter Tavernier, Ghent University – vestigate the following questions. Which projects have the iMinds, Department of Information Technology, Gent, Belgium, potential to impact the industry, who are the prominent e-mail: [email protected] Bram Naudts, Didier Colle, Mario Pickavet, Sofie Verbrugge: Ghent players, what are their motivations, what are the opportu- University – iMinds, Department of Information Technology, Gent, nitiesfornovelpartiesorprojects?Inordertotacklethese Belgium in a structured way, Section 2 introduces the architectural Authenticated | [email protected] author's copy Download Date | 2/8/16 12:12 PM 268 | W. Tavernier et al., Can open-source projects (re-)shape the telecommunication market? DE GRUYTER OLDENBOURG n o i Management t Cloud Service Architecture Control a c i Layer l NetworkNetwork NFV Applicaons CloudCloud ApplicaonsApplicaons p ApplicaonsApplicaons p A Layer n o i t a Orchestraon r t s Plaorm Orchestraon e Services h c r Management Management Components Layer O SDN-controlled Network Network Architecture SDN-controlled r e y a SDNSDN CCloudloud L l ControlControl NetworkNetwork SeServicesrvices ManagementManagement o CloudCloud ServicesServices r t SowareSo ware SowareSo ware n o C virtualizaonvirtualizaon llayerer NETNET HW NETNET HW COMPCOMP HHWW STORSTOR HHWW NETNET HW NETNET HW STORSTOR HHWW COMPCOMP HWHW Layer Infra. Figure 1: Network and Cloud control architectures. context of telecom and cloud networks and introduces im- 2.1 Overarching architecture portant SDN- and NFV-related concepts. In Section 3 we in- vestigate the role of OSS projects by providing an overview Modern network architectures are structured into multi- of existing projects, identifying their main contributions ple functional layers of smaller components. This modu- and dependencies, as well as the resulting gaps within lar approach reduces complexity, enhances component re- the SDN/NFV open-source software landscape. In addi- usability, and enables multiple migration paths towards tion, an analysis is made of the impact of the range of li- future architectures. Recent softwarization and virtualiza- cense policies these projects might have and the role that tion tendencies have only further accumulated the de- standards development organizations can play. At last, the composition of functional components and layers within paper concludes with some lessons learned and potential architectures. By decoupling the forwarding- from con- future topics in Section 4. trol functionality, SDN transformed previously monolithic switches/routers into two multiple independent compo- nents. Server- and network virtualization mechanisms on 2 SDN/NFV network architecture their turn introduced additional functional splits which isolate data plane functionality of its underlying hardware This section shortly sketches the main functional compo- platform. nents and layers in the SDN control architecture of a mod- NFV brings together two areas: i) the (software- ern telecom network supporting NFV in relationship to the driven¹) control of communication networks, and ii) the most important standardization bodies, in order to pro- control of cloud (service) platforms. Both control architec- vide context for the SDN/NFV open source projects which ture are depicted in Figure 1.Thefirst(markedinblue)is will be analyzed later. Particular attention will be given to in charge of controlling network of switching and routing the concept of Service Function Chaining, as it plays a cru- equipment, the second (in orange) is in charge of creating cial role in linking services to the virtualization of network and exposing cloud networks, i. e. a network of re-usable functions. 1 In the context of this paper we focus on SDN-controlled networks, although traditional distributed routing protocols could also be con- sidered as the control layer of communication networks. Authenticated | [email protected] author's copy Download Date | 2/8/16 12:12 PM DE GRUYTER OLDENBOURG W. Tavernier et al., Can open-source projects (re-)shape the telecommunication market? | 269 Access Network Data Center(s) vProbevProbe vCachevCache vCachevCache vProbevProbe vProbevProbe Physical Provider Premises Set-Top Home Agg Core Streaming Content vPEvPE vFWvFW Box Gateway Switch Router server storage Physical Customer Premises ISPs Legend: Internet/WAN vProbe = virtual probe vPE= virtual Provider Edge vCache = virtual Cache vFW = virtual FireWall Figure 2: Service Function Chain for multimedia delivery. compute and storage servers for the purpose of, e. g., functions, e. g., firewalling, intrusion prevention or server building web services. The control architecture of both do- load balancing. The merit of NFV is to virtualize these mains follows a roughly similar 3-layered approach, as de- NFs enabling to deploy them on multi-purpose hardware picted in Figure 1. At the lowest layer, infrastructure re- (servers). Service Function Chaining emerged as a way to sources form the physical foundation on top of which ser- describe the traffic steering in between the necessary NFs vices are provided. Communication networks rely on net- building the service. Traffic steering could refer to a simple work hardware such as switches and routers, Cloud infras- sequence of involved functions, or chain, but also might tructures rely on (interconnected) compute and storage include a complex mesh-like interaction between these hardware (servers). A second layer, the Control Layer in- components, requiring a forwarding overlay between the terconnects the components of the infrastructure layer via network functions