Network Function Virtualization Part 3 - Architecture of NFV

Hello Everyone,

Hope you are doing well. 

Because I had to work on few important tasks last 2-3 weeks, I regret for delay in posting this.  But am sure, this one will connect well with last two articles and gives the clear picture of what NFV is all about. 

In the previous ones we discussed about Hypervisors and the need of NFV . We are discussing about NFV Architecture in this article. 

What all the things required to set up a NFV ? or What does a NFV architecture consists of ?

Let me list them and try to brief their role in NFV environment. 

Hardware Resources 

Basic hardware resources like computing hardware, storage hardware & network hardware are required for setting up an NFV. These are general purpose hardwares with a flexibility of need basis scaling 

-Computing hardware is assumed to be COTS (Commercial of the shelf ) as opposed to purpose specific hardware

-Storage devices can be Network Attached Storage (NAS) or storage that resides on the server itself

-Network resources are comprised of Switching functions.

Virtualization Layer or Virtualization resources 

Virtualization layer decouples the VNFs ( Virtual Network Function - explanation given below)from hardware resources and thus ensures realization of hardware independent network functions 

The main important role of virtualization layer is to provide virtual resources to VNFs.  Typically hypervisors are used in the virualization layer to provide these services .(refer article 1 for details about hypervisors)

Hardware resources along with virtualization layer is called as NFVI or NFV infrastructure (refer figure -2, NFV Architecture).In general NFVI is the totality of hardware and software 

Fig.2- NFV Architecture block diagram

This NFVI can be in one location or can be spread across different locations. It can be of one infrastructure  provider or can belong to multiple providers.

In my small lab, I had used GNS3 as a virtualization software which was installed on high configuration Windows system. On GNS3, IOS of routers were emulated and a virtual topology was built for testing the network management features. This was for one of our client. I will share my experience on this as a separate article.

VNF

VNF is a virtualization of a network function. Let us consider some of the network functions, for example, DHCP servers. DHCP is a dynamic host configuration protocol. DHCP servers dynamically assign IP addresses to network hosts with some predefined rules/conditions. Usually the routers support this DHCP function.

In this context, DHCP function can be realized virtually without the need of dedicated proprietary router hardware.

let me take another example of network function, MME. Mobile Management Entity. MME is an important network element in Evolved Packet Core(EPC) of 3GPP's System Architecture Evolution (SAE)

MME is the main signaling node in EPC. It is responsible for initiating paging, authentication of the mobile device, and location updates (tracking area updates).

With development of network virtualization, the function of MME can be realized virtually on general purpose hardware.

Like this, there are many examples of network functions - S-GW & P-GW of EPC, Firewalls, etc 

EMS

Management software, typically EMS (Element Management System) is needed to manage the network functions i.e. VNFs here.

VIM

Another important element which comprises of NFV architecture is Virtual Infrastructure Manager

Its role is to control and manage the interaction of a VNF with a computing hardware, storage and network resources 

Virtual Infrastructure Manager performs resource management and is incharge of the inventory of software and hardware resources

Allocation of virtualization enablers, increase and decrease of the hardware resources based on the need is done by VIM

It also does operations like Management of NFV infrastructure, root cause analysis of performance issues of NFVI, collection of information for capacity planning, monitoring and optimization.

VNF Manager 

VNF manager is responsible for VNF lifecycle management ( instantiation, update,query,scaling and termination).   A separate VNF Manager may be deployed for each VNFs or one single VNF manager can serve multiple VNFs

Orchestrator 

literall meaning is - to arrange or control of the elements 

Its responsible for creating a network service, scale a network service terminate a network service 

The NFV Management and orchestration is called as NFV-MANO which in total takes care of NFV Management.

Hope the content was informative and could add some value in understanding NFV. Suggestions and feedback are welcome.  Will take some case studies about NFV in the next article.