In this post i though to list down the top 40 definitions and terminologies around network functions virtualization (NFV). the mini topics below cover wide range of definitions that you should definitely come across when starting your NFV journey.

1. Grub:

Basically, GRUB bootloader is the software that loads the Linux kernel. (It has other uses as well).

It is the first software that starts at a system boot. When the computer starts, BIOS first run a Power-on self-test (POST) to check hardware like memory, disk drives and that it works properly.

Then BIOS checks the Master Boot Record (MBR), which is a 512 byte section located first on the Hard Drive. It looks for a bootloader (like GRUB). The hard drive’s partition tables are also located here.

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Then you’ll be prompted by the GRUB menu which can contain a list of the operating systems installed, or perhaps the different kernels installed in a Linux distro.

When you choose which distro or kernel you want to use, GRUB loads the selected kernel. The kernel starts init (or systemd), which is the first process to start in Linux. Init then starts other processes like network services and other that you might have configured to start at boot time.

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2. CPU Affinity & NUMA (CPU Pinning)

Legacy applications used to run on single core processors, now with the introduction of multi-threading and mult-core processor you might notice that the OS (windows, linux, etc..) is distributing the load on all cores so there could be a balance in the usage, however, in some virtual environment you might need to dedicate a CPU to specific VM doing a specific Network Function.

in OpenStack The NUMA topology and CPU pinning features provide high-level control over how instances run on hypervisor CPUs and the topology of virtual CPUs available to instances. These features help minimize latency and maximize performance.


Symmetric multiprocessing (SMP)
SMP is a design found in many modern multi-core systems. In an SMP system, there are two or more CPUs and these CPUs are connected by some interconnect. This provides CPUs with equal access to system resources like memory and input/output ports.
Non-uniform memory access (NUMA)
NUMA is a derivative of the SMP design that is found in many multi-socket systems. In a NUMA system, system memory is divided into cells or nodes that are associated with particular CPUs. Requests for memory on other nodes are possible through an interconnect bus. However, bandwidth across this shared bus is limited. As a result, competition for this resource can incur performance penalties.
Simultaneous Multi-Threading (SMT)
SMT is a design complementary to SMP. Whereas CPUs in SMP systems share a bus and some memory, CPUs in SMT systems share many more components. CPUs that share components are known as thread siblings. All CPUs appear as usable CPUs on the system and can execute workloads in parallel. However, as with NUMA, threads compete for shared resources.

In OpenStack, SMP CPUs are known as cores, NUMA cells or nodes are known as sockets, and SMT CPUs are known as threads. For example, a quad-socket, eight core system with Hyper-Threading would have four sockets, eight cores per socket and two threads per core, for a total of 64 CPUs.

the following links include more details on the definition and usage of CPU Pinning.

3.  IRQ (interrupt request)

An IRQ (interrupt request) value is an assigned location where the computer can expect a particular device to interrupt it when the device sends the computer signals about its operation. For example, when a printer has finished printing, it sends an interrupt signal to the computer. The signal momentarily interrupts the computer so that it can decide what processing to do next. Since multiple signals to the computer on the same interrupt line might not be understood by the computer, a unique value must be specified for each device and its path to the computer. Prior to Plug-and Play (PnP) devices, users often had to set IRQ values manually (or be aware of them) when adding a new device to a computer.

If you add a device that does not support Pnp, the manufacturer will hopefully provide explicit directions on how to assign IRQ values for it. If you don’t know what IRQ value to specify, you’ll probably save time by calling the technical support phone number for the device manufacturer and asking.

4. network controller:

functional block that centralizes some or all of the control and management functionality of a network domain and may provide an abstract view of its domain to other functional blocks via well-defined interfaces network forwarding path: ordered list of connection points forming a chain of NFs, along with policies associated to the list

5. Network Function (NF):

functional block within a network infrastructure that has well-defined external interfaces and well-defined functional behaviour

6. Network Functions Virtualisation (NFV):

principle of separating network functions from the hardware they run on by using virtual hardware abstraction Network Functions Virtualisation Infrastructure (NFVI): totality of all hardware and software components that
build up the environment in which VNFs are deployed

NOTE: The NFV-Infrastructure can span across several locations, e.g. places where data centres are operated. The network providing connectivity between these locations is regarded to be part of the NFVInfrastructure. NFV-Infrastructure and VNF are the top-level conceptual entities in the scope of Network Function Virtualization. All other components are sub-entities of these two main entities.

7. Network Functions Virtualization Infrastructure (NFVI) components:

NFVI hardware resources that are not field replaceable, but are distinguishable as COTS components at manufacturing time Network Functions Virtualisation Infrastructure Node (NFVI-Node): physical device[s] deployed and managed as a single entity, providing the NFVI Functions required to support the execution environment for VNFs

8. Network Functions Virtualisation Management and Orchestration Architectural Framework (NFV-MANO Architectural Framework):

collection of all functional blocks (including those in NFV-MANO category as well as others that interwork with NFV-MANO), data repositories used by these functional blocks, and reference points and interfaces through which these functional blocks exchange information for the purpose of managing and orchestrating

9. NFV Network Functions Virtualisation Orchestrator (NFVO):

functional block that manages the Network Service (NS) lifecycle and coordinates the management of NS lifecycle, VNF lifecycle (supported by the VNFM) and NFVI resources (supported by the VIM) to ensure an optimized allocation of the necessary resources and connectivity

10. Network Interface Controller (NIC):

device in a compute node that provides a physical interface with the infrastructure network.

11. Network Point of Presence (N-PoP):

location where a Network Function is implemented as either a Physical Network Function (PNF) or a Virtual Network Function (VNF)

12. network service:

composition of Network Functions and defined by its functional and behavioral specification.

13. network service descriptor:

template that describes the deployment of a Network Service including service topology (constituent VNFs and the relationships between them, Virtual Links, VNF Forwarding Graphs) as well as Network Service characteristics such as SLAs and any other artefacts necessary for the Network Service on-boarding and lifecycle management of its instances

14. network service orchestration:

subset of NFV Orchestrator functions that are responsible for Network Service lifecycle management

15. network service provider:

type of Service Provider implementing the Network Service.

16. network stability:

ability of the NFV framework to maintain steadfastness while providing its function and resume its designated behaviour as soon as possible under difficult conditions, which can be excessive load or other anomalies not exceeding the design limit.


17. NF forwarding graph:

graph of logical links connecting NF nodes for the purpose of describing traffic flow between these network functions

18. NF set:

collection of NFs with unspecified connectivity between them

19. NFV framework:

totality of all entities, reference points, information models and other constructs defined by the specifications published by the ETSI ISG NFV.

20. resiliency:

ability of the NFV framework to limit disruption and return to normal or at a minimum acceptable service delivery level in the face of a fault, failure, or an event that disrupts the normal operation

21. NFV Scaling

scaling: ability to dynamically extend/reduce resources granted to the Virtual Network Function (VNF) as needed

22. service continuity:

continuous delivery of service in conformance with service’s functional and behavioural specification and SLA requirements, both in the control and data planes, for any initiated transaction or session till its full completion even in the events of intervening exceptions or anomalies, whether scheduled or unscheduled, malicious, intentional or unintentional

NOTE 1: From an end-user perspective, service continuity implies continuation of ongoing communication sessions with multiple media traversing different network domains (access, aggregation and core network) or different user equipment.

NOTE 2: End to end service continuity requires that the service is delivered with service quality defined by an SLA. This is true regardless if the service is delivered via a non-virtual network, virtual network or a combination.

23. Service Level Agreement (SLA):

negotiated agreement between two or more parties, recording a common understanding about the service and/or service behaviour (e.g. availability, performance, service continuity, responsiveness to anomalies, security, serviceability, operation) offered by one party to another, and the measurable target values characterizing the level of services. that doesnt include the business aspect of the SLA.

24. Virtualised Network Function (VNF):

implementation of an NF that can be deployed on a Network Function Virtualisation Infrastructure (NFVI)

25. Virtualised Network Function Instance (VNF Instance):

run-time instantiation of the VNF software, resulting from completing the instantiation of its components and of the connectivity between them, using the VNF deployment and operational information captured in the VNFD, as well as additional run-time instance-specific information and constraints.

26. Virtualised Network Function Component (VNFC):

internal component of a VNF providing a VNF Provider a defined sub-set of that VNF’s functionality, with the main characteristic that a single instance of this component maps 1:1 against a single Virtualisation Container.

27. Virtualised Network Function Component (VNFC) Instance:

instance of a VNFC deployed in a specific Virtualisation Container instance. It has a lifecycle dependency with its parent VNF instance Virtualised Network Function Descriptor (VNFD): configuration template that describes a VNF in terms of its deployment and operational behaviour, and is used in the process of VNF on-boarding and managing the lifecycle of a
VNF instance

28. Virtualised Network Function Manager (VNFM):

functional block that is responsible for the lifecycle management of VNF

29. Virtualised Network Function Package (VNF Package):

archive that includes a VNFD, the software image(s) associated with the VNF, as well as additional artifacts, e.g. to check the integrity and to prove the validity of the archive

30. Packet Switching System vs Circuit-switching systems

A type of communications in which a dedicated channel (or circuit) is established for the duration of a transmission. The most ubiquitous circuit-switching network is the telephone system, which links together wire segments to create a single unbroken line for each telephone call.

The other common communications method is packet switching, which divides messages into packets and sends each packet individually. The Internet is based on a packet-switching protocol, TCP/IP.

Circuit-switching systems are ideal for communications that require data to be transmitted in real-time. Packet-switching networks are more efficient if some amount of delay is acceptable.

31. Bandwidth

a unit of measurement that quantifies the rate at which data can be transmitted by the network

One megabit per second (Mbit/s) is equal to 1,000,000 bits per second

One gigabit per second (Gbit/s) is equal to 1,000,000,000 bits per second

One terabit per second (Tbit/s) is equal to 1,000,000,000,000 bits per second

One megabyte per second (MB) is equal to 1,000,000,000 bytes per second or 8 Mbps

One gigabyte per second (GB) is equal to 1,000,000,000 bytes per second or 8 Gbps

One terabyte per second (TB) is equal to 1,000,000,000,000 bytes per second or 8 Tbps

One exabyte per second (EB) is equal to one quintillion bytes per second

32. Demilitarized Zone (DMZ) –

a physical or logical sub-network that protects an organization’s external-facing services, such as Web and email, from an un-trusted network typically the Internet. The goal of a DMZ, sometimes called a perimeter network, is to add a layer of security to protect those resources and contain attacks that successfully infiltrate that area.

33. Broadband

a high-speed network connection that allows you to do several things at the same time.

34. European Telecommunications Standards Institute (ETSI):

an independent, non-profit organization responsible for driving standardization in the telecommunications industry in Europe

35. Institute of Electrical and Electronics Engineers (IEEE)

the world’s largest technical professional association. IEEE has more than 425,000 members in over 160 countries, who participate in IEEE activities, which span publishing technical literature, sponsoring conferences, developing standards, providing continuing education and training courses, giving grants and recognizing technical accomplishments. For more information, please visit our

36.  Multi-Tenant

the ability to partition a single network, system or computing resource to support multiple clients. Each client can only see and manage their part.

37. Platform-as-a-Service (PaaS)

on-demand computing platforms delivered via the cloud that can be used to run applications. Typically includes the underlying computer and storage resources.

38. Session Initiation Protocol (SIP, RFC 2543)

part of IETF‘s multimedia data and control protocol framework. SIP is a powerful client-server signaling protocol used in VoIP networks. SIP handles the setup and tear down of multimedia sessions between speakers; these sessions can include multimedia conferences, telephone calls, and multimedia distribution.

SIP is a text-based signaling protocol transported over either transmission control protocol (TCP) or user datagram protocol (UDP), and is designed to be lightweight. It inherited some design philosophy and architecture from the hypertext transfer protocol (HTTP) and simple mail transfer protocol (SMTP) to ensure its simplicity, efficiency and extensibility.

SIP uses invitations to create session description protocol (SDP) messages to carry out capability exchange and to setup call control channel use. These invitations allow participants to agree on a set of compatible media types. SIP supports user mobility by proxying and redirecting requests to the user’s current location. Users can inform the server of their current location (IP address or URL) by sending a registration message to a registrar. This function is powerful and often needed for a highly mobile voice user base.


39. Software-Defined Networking (SDN)

a new approach to designing, building and managing networks by separating the control and forwarding planes. For more information visit


40. Traffic Shaping (Packet Shaping)

the practice of controlling how traffic is transported throughout the network to assure a certain level of availability, performance, quality-of-service (QoS) , or return on investment (ROI).

Also Check these references References:

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