A virtualized network function, or VNF, is implemented within one or more virtual machines or containers running different software and processes, on top of commercial off the shelf (COTS) high-volume servers, switches and storage devices, or even cloud computing infrastructure, instead of having custom hardware appliances for each network function thereby avoiding vendor lock-in.
Other examples of NFV include virtualized load balancers, firewalls, intrusion detection devices and WAN accelerators to name a few.
Product development within the telecommunication industry has traditionally followed rigorous standards for stability, protocol adherence and quality, reflected by the use of the term carrier grade to designate equipment demonstrating this high reliability and performance factor.
[3] While this model worked well in the past, it inevitably led to long product cycles, a slow pace of development and reliance on proprietary or specific hardware, e.g., bespoke application-specific integrated circuits (ASICs).
In October 2012, a group of telecom operators published a white paper[4] at a conference in Darmstadt, Germany, on software-defined networking (SDN) and OpenFlow.
The Call for Action concluding the White Paper led to the creation of the Network Functions Virtualization (NFV) Industry Specification Group (ISG) [5] within the European Telecommunications Standards Institute (ETSI).
These attributes, referred to as carrier-grade[11] features, are allocated to an orchestration layer in order to provide high availability and security, and low operation and maintenance costs.
[13] The first ETSI NFV ISG-approved public multi-vendor proof of concept (PoC) of D-NFV was conducted by Cyan, Inc., RAD, Fortinet and Certes Networks in Chicago in June, 2014, and was sponsored by CenturyLink.
[15] During 2014 RAD also had organized a D-NFV Alliance, an ecosystem of vendors and international systems integrators specializing in new NFV applications.
[4] In essence, SDN is an approach to building data networking equipment and software that separates and abstracts elements of these systems.
[20] For example, within each NFV infrastructure site, a VIM could rely upon an SDN controller to set up and configure the overlay networks interconnecting (e.g. VXLAN) the VNFs and PNFs composing an NS.
Its immediate applications are numerous, such as virtualization of mobile base stations, platform as a service (PaaS), content delivery networks (CDN), fixed access and home environments.
Virtualization of network functions deployed on general purpose standardized hardware is expected to reduce capital and operational expenditures, and service and product introduction times.
The NFV platform software is responsible for dynamically reassigning VNFs due to failures and changes in traffic load, and therefore plays an important role in achieving high availability.
[35] Significant performance improvements are being reported by NFV suppliers for both OVS and Accelerated Open vSwitch (AVS) versions.
As VNFs replace traditional function-dedicated equipment, there is a shift from equipment-based availability to a service-based, end-to-end, layered approach.
Swagger) representation of the API specifications is available and maintained on the ETSI forge server, along with TOSCA and YANG definition files to be used when creating deployment templates.
OS Container management and orchestration An overview of the different versions of the OpenAPI representations of NFV-MANO APIs is available on the ETSI NFV wiki.
Additional studies are ongoing within ETSI on possible enhancement to the NFV-MANO framework to improve its automation capabilities and introduce autonomous management mechanisms (see ETSI GR NFV-IFA 041 ) Recent performance study on NFV focused on the throughput, latency and jitter of virtualized network functions (VNFs), as well as NFV scalability in terms of the number of VNFs a single physical server can support.
openNetVM is an open source version of the NetVM platform described in NSDI 2014 and HotMiddlebox 2016 papers, released under the BSD license.
The source code can be found at GitHub:openNetVM[45] From 2018, many VNF providers began to migrate many of their VNFs to a container-based architecture.
These include auto-scaling, supporting a continuous delivery / DevOps deployment model, and efficiency gains by sharing common services across platforms.
Utilizing containers, and thus dispensing with the overhead inherent in traditional virtualization through the elimination of the guest OS can greatly increase infrastructure resource efficiency.