The Management and Organization Working Group of the European Telecommunications Standards Institute (ETSI MANO) defines the network functions virtualization management and orchestration (NFV–MANO) architecture as comprising three major functional blocks: virtual infrastructure manager (VIM), VNF manager, and NFV orchestrator. The VIM is responsible for controlling and managing the NFV infrastructure (NFVI) compute, storage, and network resources, usually within one operator’s infrastructure domain. The VIM is a specific part of the MANO framework, but can have multiple instances in a network. There are two general kinds of instances. Some manage multiple types of NFVI resources, or they can be specialized to handle a certain type.
In November 2014, the NFV-MANO Working Group closed and the ETSI NFV Interfaces and Architecture (IFA) Working Group was created to take over work on MANO standards.
The VIM block is responsible for managing the virtualized infrastructure of an NFV-based solution, keeping an inventory of the allocation of virtual resources to physical resources. This allows for the orchestration of the allocation, upgrade, release, and reclamation of NFVI resources and the optimization of their use.
The VIM block supports the management of VNF forwarding graphs by organizing virtual links, networks, subnets, and ports. The VIM architecture also manages security group policies to ensure access control.
The VIM block also manages a repository of NFVI hardware resources (compute, storage, networking) and software resources (hypervisors), along with the discovery of a resource’s capabilities and features to optimize its use.
The VIM block performs other functions as well — such as collecting performance and fault information via notifications, managing software images (add, delete, update, query, copy) as requested by other NFV-MANO functional blocks, and managing catalogs of virtualized resources that can be used from the NFVI. The southbound interfaces of a VIM interacts with Network Controllers to carry out these functions.
The ETSI-based project, Open Source MANO, has added functionality to their VIM component over the course of its releases. These include increased interoperability between components, using OpenVIM for its capabilities in resource orchestration, making a VIM plugin, improved error handling, multiple VIM integration, and fault and performance management of network services.
VIMs are critical to realizing the business benefits enabled by NFV as they coordinate the physical resources necessary to deliver network services. This is particularly visible for infrastructure-as-a-service (IaaS) providers. The IaaS providers have to ensure that their servers, networks, and storage work smoothly with the user equipment at a customer’s location. In order to ensure that smoothness, VIM dynamically allocates resources based on what is needed. Some consider it a morphing of a traditional OS, but it doesn’t work with a single node. Instead, it collects information from many machines simultaneously and uses that information for management functions.
When VIMs are allocating resources appropriately, users have a quality experience even if there is a lot of demand on the virtualized infrastructure resources.
The VIM Market
Many vendors offer VIMs. Cisco offers a VIM product that manages the software and hardware of the customer’s NFVI. The product is able to allocate physical resources, while the ETSI standard only gave the VIM control over virtual resources. The company also claims its VIM product will minimize surface area for attacks.
Most vendors base their VIM products on technology from VMware or OpenStack. VMware offers vSphere, a proprietary, yet market-proven VIM. VMware can utilize its VIM to help customers transform existing IT infrastructures into public or hybrid clouds.
VMware has worked closely with the ETSI hosted project called Open Source MANO (OSM) to “capitalize on the synergy between standardization and open source approaches.” The stack that OSM has been working on is aligned with ETSI NFV models. OSM’s first release dates back to October 2016 with a technical overview of its work.
And then there is OpenStack. Some industry users point out that OpenStack provides more functionality than simple VIM services. But it’s easy to see why OpenStack is deployed as a VIM: it controls pools of compute, storage, and networking resources that can be managed through the OpenStack API. Many vendors have created OpenStack implementations of their own, including Red Hat, Mirantis, Oracle, and VMware.
Based on the popularity of OpenStack and the functions the VIM provides, it is clear that the role of a virtual infrastructure manager is a critical component of the NFV-MANO architecture. It is necessary to realize the increased value promised by NFV-based solutions.
The NFV market is evolving rapidly as technology and service providers alike use pieces of open source projects and add them to their existing software solutions to provide a full complement of NFV functions.
Updated April 2019