Network function virtualization (NFV) Architecture

network function virtualization is the concept of a computer network architecture where traditional physical network elements replaced by virtual machines running the same functionality running on standard, high-performance industrial servers.

The current computer network in enterprises and telecommunication providers is the most common consist of physical proprietary equipment. Ownership means that their manufacturer owns the software technology that is important for their operation and management.

This fact leads to compatibility problems with the use of devices from different manufacturers, and the need to use different administration tools for different network devices and often also to so-called vendor lock-in.

Vendor lock-in status means that if you need to expand network infrastructure is required for reconfiguration to be resolved by the manufacturer, from which the network elements of the current infrastructure come from, even though the cost of similar solutions from a competitor could be lower.

Virtualized network devices can be avoided, because software solutions can easily be developed as open or open-source. This open solutions in the field of networking virtualization very often arise just because of avoiding problems with vendor lock-in.

Virtualized solutions are also by nature virtualisation independent of the hardware used, which brings independence from the manufacturer physical equipment.

The European Telecommunications Standards Institute (ETSI) is an international community network service providers who collaborate on creating new standards and solving in the field of computer networks. This organization introduced the Network function virtualization framework in 2013, which standardizes the use of the concept.

∙ Virtual Network Functions (VNF):
VNF is a software implementation of a particular network equipment feature that is running in one or more virtual machines or containers. In the whole infrastructure
NFV typically have several of them.
∙ Network Functions Virtualization Infrastructure (NFVI):
It is a subsystem consisting of all the physical equipment used, such as servers, standard switches, or bulk storage, and software technologies that enable virtualization, typically hypervisors.
∙ Management and Orchestration (MANO):
MANO is a subsystem that provides the entire framework administration. The message VNF takes care of Virtual Networks Functions Manager (VNFM), Virtualization Infrastructure Manager (VIM), Virtualization Infrastructure (VFM), and NFV Networking Virtualization Orchestrator (NFVO) MANO

Figure 3.1 also shows a section called OSS / BSS, Operations Support Systtems, and Business Support Systems business support systems. These are enterprise information systems or other institutions where virtual network infrastructure is operated. Linking these systems to systems in the MANO component will ensure integration into the current operational information environment.

The community of ETSI providers, along with the NFV framework release, have also identified some
objectives that it should achieve.

∙ Fast development of network and end-to-end services with the help of software tools for their deployment and management,
· Streamlining traffic through automation and standard operating procedures,
• Reduce energy consumption by delivering even load distribution and automatic disconnection of unused physical devices,
∙ Increased flexibility by assigning VNF to specific hardware,
• Reduced acquisition and operating costs.

Network function virtualization in real life

In traditional host networks, network functions are implemented within everyone physical equipment as proprietary software. NFV this output is changing, here is the network devices implemented as virtual machines or containers, and network functions such as software independent of the hardware used. The network function is for example routing, firewall, load-balancing, etc.

Implementing virtual network functions with you in addition to being independent of hardware platform and manufacturers also bring the possibility of splitting a certain network function, each of which can be operated as a separate Network function virtualization. For example, the different router functions can be divided into VNF and together form one router.

Virtualization of network functions brings also the advantage of easy substitutability scalability while maintaining the same hardware. If, for example, a type of VNF does not meet the expected requirements, it can be replaced much more easily than physical devices. Expansion can only be done by installing new VNFs. If the hardware performance is not enough, it is also possible to expand the hardware and maintain the same virtual infrastructure.

In case you need to replace all or most of the hardware on which it is running virtualization layer, due to lack of performance, it is possible without virtually no virtual virtualization transfer the machines to new hardware and preserve the entire infrastructure again.

Another significant advantage of using NFV is better management of available resources. Physical network equipment has only its own resources, so it is always necessary to have it overdimension. The only thing that happens is that the whole network is drawn to the maximum, usually at a certain point, top-level development concerns only some of its parts.

For this reason, it is often the need to have powerful hardware across the network or a large part of it to handle these fluctuations. This leads to a small amount of physical equipment, and thus to the waste of resources most of the time are not used.

Since VNFs share hardware resources, they can be managed much more efficiently. The hardware can be over-sized to handle top-notch for a particular part network. These resources can then be dynamically allocated and removed by different VNFs based on current needs, and consequently to achieve more efficient management with them. Element Management Systems (EMS) can handle part of these tasks.

These are VNF-like services that help the orchestra with VNF management. Relationship EMS and VNF can be either one to one or one to many.

VNF also has the ability to manage their life cycle. This means that each VNF is may be in any of the following conditions:
∙ Preparation: In this state, network function virtualization is defined in a virtualization platform, but still is not running. In practice, this means that a virtual machine disk image is uploaded, or a template is prepared for the VNF to be put into operation.
∙ Deployment: As the name itself says, it is the start of a given VNF and its initial configuration.
∙ Monitoring: In this state, the VNF is already deployed and performs its function. Continuously his status is being monitored for whether there were any problems.
∙ Scaling: At different times, the VNF can be changed, so it is possible its scaling. In low recovery, the means are eliminated and at high turn added.
∙ Updating light: In the event of anxiety it is possible to apply to some VNF some pre-prepared procedures for its entry into normal operation. These steps are performed just in the phase of recovery.
∙ Updating: When installing new updates for VNF, it is possible to apply this state without having to delete the VNF and reload it deployed.
∙ Stop: If it is necessary to replace the VNF or its redundancy, it can be terminated after applying this state.



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