Virtualization is driving the modernization of the cable infrastructure. Monolithic CCAP/CMTS hardware isn’t adequate for the needs of today’s customers. A virtual CCAP, with QAM moved out to remote PHY devices (RPDs), provides the scalability which cable operators need.

Distribution and scalability bring challenges of their own. Virtual resources need to work efficiently with physical ones. This requires supporting software which lets the infrastructure work smoothly. A virtual infrastructure manager (VIM) handles this task.

RPD Deployment Made Simple Webinar – Learn how to solve configuration, management, and monitoring challenges posed by large amounts of Remote PHY devices (RPDs) connected to multiple CCAPs with a low-code/no code orchestration platform.

What is a Virtual Infrastructure Manager?

A VIM runs on top of a hypervisor in an NFV environment. The hypervisor allocates and manages virtual machines. The VIM deals with the allocation of resources in the NFV infrastructure (NFVI). They include computational resources (processors), storage, and network resources. A VIM allows the allocation to happen based on current requirements, rather than being statically allocated.

The VIM carries out several tasks:

  • Allocating resources in accordance with traffic engineering rules.
  • Support for defining operational rules.
  • Definition of hub-to-facility mapping.
  • Providing information for provisioning virtual infrastructure orchestration (VIO).

The RPDs and the customers behind them are the consumers of resources. Their requirements will vary depending on their service level and what they are currently doing. The VIM helps to ensure that they get the level of service they expect and have sufficient resources to meet their needs at any given moment, without excessively impacting other users.

OpenStack is a widely used VIM, designed for a heterogeneous infrastructure. It’s open-source software, available under the Apache 2.0 license. Administrators can use it to manage infrastructure through its dashboard or with a custom interface using its API. CableLabs offers SNAPS-OpenStack, a wrapper around a containerized version of OpenStack. The combination lets network operators use commodity hardware or cloud services together with open-source software as the basis of their virtual infrastructure.

NFVI vs. static infrastructure

A good way to understand the role of a VIM is to contrast NFVI with a non-virtual infrastructure. Without virtualization, each process and application run on a physical machine. Its workload may be shared among multiple machines, but they’re a well-defined set of hardware.

In a static infrastructure, application or service has a fixed set of resources available. They include the machine which it runs on and external resources. The latter include NAS storage, cloud services, database servers, and so on. Each application shares resource usage with others, but it’s a comparatively straightforward task. System managers balance processes by setting account limits, process priorities, and memory allocations. If a machine is overloaded, the administrator will move some processes to another system or ask for more hardware.

Virtual machines and NFVI make everything a variable. The amount of processing power, memory, storage, and bandwidth can change with the flick of a configuration parameter. Even resources which used to be hardware devices, such as switches and firewalls, can be created and destroyed as needed. However, they have to be created out of a limited set of physical resources.

It’s possible to run a virtualized network with fixed allocation parameters, but it isn’t efficient. A process’s needs change with the demands placed on it. An allocation which is inadequate at one moment may be wasteful an hour later.

A VIM sets criteria for creating and allocating resources, based on dynamic considerations. It balances the requirements of all processes so that they get what they need but can’t hog a resource to the detriment of others. Doing this well is especially important when the processes represent customers, each of whom wants the best service possible.

The dynamic nature of the virtualized CCAP requires network-level tools to balance the complicated array of competing processes. Without them, it doesn’t realize its full advantage over a static infrastructure, and its size makes it harder to manage. The virtual infrastructure manager reduces the amount of required manual intervention and ensures that services stay at a high level of quality.

RPD Deployment Made Simple Webinar – Learn how to solve configuration, management, and monitoring challenges posed by large amounts of Remote PHY devices (RPDs) connected to multiple CCAPs with a low-code/no code orchestration platform.