NFV Orchestrator ( NFVO)

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The NFV Orchestrator or NFVO has two primary responsibilities

1. Resource Orchestration:

Resource Orchestration refers to the management of virtualised and non-virtualised resources in the Network Functions Virtualisation Infrastructure (NFVI). It will basically oversee the allocation of resources and monitor the allocated resources used by the services.

Virtualised Resources include:

• Compute Resources

Resources such as CPU and Memory which could be retrieved from a host or bare metal or from a Virtual machine.

• Storage Resources

• Network Resources

Resources such as networks, ports, subnets, forwarding rules etc needed for intra and inter VNF communications.

Non Virtualised Resources are restricted to providing connectivity between the Physical Network Functions ( PNF) and VNF and when a VNF is distributed between physical and virtual resources.

2. Network Service Orchestration:

Network Service Orchestration refers to how NFVO will manage the service deployment which includes VNF deployment, links between the VNFs and the connection details between them. It also manages the service deployment lifecycle.

Network Service orchestration refers to management of network services between the VNFs and PNFs. It is responsible for

• Creation and termination of networks between VNFs
• Increase/Decrease capacity of Network Service
• Updating/Querying VNF Forwarding Graphs

A few functions of NFVO is as follows

• Manage the various deployment templates

NFVO needs to design and manage various catalogs like

• NS Catalogue which contains details on network connectivity between VNFs and PNFs,
• VNF Catalogue which contains the VNF resources structure i.e. type of VNFs , no of CPUs, amount of memory, storage etc for the VNF
• NFVI Catalogue which contains details on the resources available on physical hardware

• Instantiation of VNFs in coordination with VNFM

NFVO has an interface towards the VIM. NFVO may have the knowledge on the various resources available at the NFVI and take a decision on the instantiation of VNFs. For e.g. If most of CPU resources in NFVI are taken by other VNFs, NFVO can decide to lower the VNF resources and start a smaller VNF.

• Validation of resource requests from VNFM

Element Managers ( EM ) may request the VNFM to instantiate a new VNF or increase resources in the current VNF. VNFM may request NFVO to authorize such an action. For e.g. say VNFs are at  90% subscriber capacity. EM will request VNFM to allocate more resources ( may be increase resources to existing VM or spawn additional VMs) to VNFM. VNFM contacts NFVO and asks to authorize this action. NFVO looks into its policy database and say it has a policy to not allocate any more resources to VNF. VNFM then, will not allocate any more resources to the VNF.

• Policy management

Policies such as affinity/anti-affinity , auto-scaling, auto-healing , fault tolerance etc can be stored in NFVO.

• Management of Network Services

NFVO has the knowledge of the entire VNF network. It has a connection to VIM, thereby having a knowledge of the NFVI as well. NFVO can use this information to determine network instances and their topology to create,terminate,update VNF Forwarding graphs.

• Statistics Collection

NFVO can collect various VNF statistics like amount of resources used by VNFs, faults and alarms triggered and other usage statistics.

• Device Management

NFVO may be able to manage the configuration of the devices (both PNF and VNF). If integrated with plugins or drivers for devices, it should be able to manage the configuration for network devices like routers, switches and mobility platforms. Data modelling languages like YANG can be used to model the configuration data as well as the state data of network element configuration (YANG is a data modelling language for NETCONF protocol).

• Multi-VIM support

Multi-VIM and Multi-Vendor support can be built in easily into a NFVO if a plugin like architecture is used for each VIM or Vendor.