Gunawardana R.S.D. Network Virtual Functions Management and Orchestration

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Cовременные информационные технологии/ 3.Программное обеспечение

Gunawardana R.S.J.

National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”

Network Virtual Functions Management and Orchestration

SDN is short for software defined networking. Software defined networking (SDN) is an approach to using open protocols, such as OpenFlow, to apply globally aware software control at the edges of the network to access network switches and routers that typically would use closed and proprietary firmware.

Software defined networking supplies with some benefits. For example, software defined networking offers numerous benefits including on-demand provisioning, automated load balancing, streamlined physical infrastructure and the ability to scale network resources in lockstep with application and data needs. As noted on Enterprise Networking Planet, coupled with the ongoing virtualization of servers and storage, SDN ushers in no less than the completely virtualized data center, where end-to-end compute environments will be deployed and decommissioned on a whim.

Legacy network infrastructure is typically a mix of vendor solutions, platforms and protocol solutions making the ultimate goal of an integrated network ecosystem a difficult process for many organizations. According to Enterprise Networking Planet, it is feasible, though perhaps not optimal, to implement software defined networking on existing physical infrastructure. Today, the enterprise and large customers look to build new SDN infrastructure from the ground up.

Software defined networks need some management and monitoring. Thus the tool called MANO was invented. It’s an open standard that specifies the software and infrastructure modules that manage the software defined networks. MANO stands for Management and Orchestration.

MANO includes three Managers:

- Virtualized Infrastructure Manager (VIM);

- VNF Manager (VNFM);

- NFV Orchestrator (VNFO).

In addition to the four blocks inside the MANO, there are two blocks outside i.e. the traditional Element Management (EM) and OSS/BSS. While the latter two blocks are not directly part of the MANO, they do exchange information with MANO ,so a learner needs to position them correctly against the MANO blocks.

Following is a description of each of these six blocks starting with Virtualized Infrastructure Manager (VIM).

VIM manages NFVI resources in “one domain”. (NFVI is the NFV Infrastructure that includes physical (server, storage etc.), virtual resources (Virtual Machines) and software resources (hypervisor) in an NFV environment).

Note the word “one domain” here. So there may be multiple VIMs in an NFV architecture, each managing its respective NFV Infrastructure (NFVI) domain. Keep this concept of “multiple VIMs” in mind as we will re-visit it again during Orchestrator section.

So, what are the typical tasks, VIM delivers? It does the following:

- manages the life cycle of virtual resources in an NFVI domain. That is, it creates, maintains and shuts down virtual machines (VMs) from physical real resources in an NFVI-specific domain;

- keeps inventory of virtual machines (VMs) associated with physical resources.

- performance and fault tolerance for the hardware in order to manage reliability, software and other, i.e. virtual, resources;

- keeps north bound APIs and thus exposes some physical and also some virtual resources to other systems that provide management.

NFVO coordinates, authorizes, releases and engages NFVI resources among different PoPs or within one PoP. This does so by engaging with the VIMs directly through their north bound APIs instead of engaging with the NFVI resources, directly.

A VNF Descriptor (VNFD) is a deployment template which describes a VNF in terms of its deployment and operational behavior requirements. It is primarily used by VNFM in the process of VNF instantiation and lifecycle management of a VNF instance. The information provided in the VNFD is also used by the NFVO to manage and orchestrate Network Services and virtualized resources on NFVI.

EM is not part of the MANO, however it has important role to play.

Element Management is responsible for the FCAPS (Fault, Configuration, Accounting, Performance and Security management) for the functional part of the VNF. If you recall, VNFM also does the FCAPS of the VNF but only for the virtual part.

To clarify with an example: Generally MANO is only responsible for the delta of the virtual and physical world. Taking VNFM as an example, it does the life cycle management of VNF and its FCAPS. In the terms of fault management it shows, if there is any issue with the spinning up of any of VNF, it will be reported by the system called VNFM but if the fault is connected to some function (i.e. some signalling issue in mobile core) it would be highlighted by component called EM.

VNFM exposes its interface to the EM in case an operator wants to use only one GUI for all work related to FCAPS (both virtual and functional).

OSS/BSS include collection of systems and applications that a service provider uses in order to operate the business.

NFV is expected to work in coordination with OSS/BSS software.

In principle it can be possible to supersede the functionalities of the current OSS/BSS systems in order to manage VNFs and NFVI in a direct fasion, but that may be a proprietary implementation of a vendor (or at least the interfaces between EM and VNFs are not yet defined by ETSI as of now). NFV is known to be an open platform, thus managing NFV entities using open interfaces (As that done in MANO) makes much more sense.

The existing OSS/BBS, for example, can value add the NFV MANO by offering additional functions if they are not supported by a certain implementation of NFV MANO. This can be done through an open reference point (Or-Ma-NFVO) between NFV MANO and existing OSS/BSS.