How Virtual Network Functions Improve Network Performance

The internet is more interconnected than ever, and workloads are growing exponentially.

The explosion of mobile, social media, cloud computing, and virtualized workload is creating new demands on networks, dramatically increasing the number of applications, users, and data packets that enterprise networks must handle. The number of links between networks is growing, creating complex connectivity problems.

This overwhelms traditional network architectures, and engineers are looking for new solutions to combat the issue.

While network functions virtualization (NFV) has been around for nearly two decades, the topic is primarily associated with mobile networks. The growing need for flexibility and agility, especially for businesses that use software-defined wide area network (SD-WAN) software, is driving NFV adoption everywhere.

Virtual network functions (VNFs) are a critical component of an NFV infrastructure (NFVi). VNFs are essential in today's networking environment because they give organizations greater flexibility with application deployment and support.

A network function (NF) is a basic unit in a network architecture with set external interfaces and functional behavior. Practically, this could include a network node or a physical appliance, like a firewall. A virtual network function is a software implementation of a network function easily deployable on virtual resources, such as virtual machines (VMs).

VNFs are a critical component of a software-defined networking (SDN) implementation. The word "virtual" in VNF is somewhat misleading because VNFs don't really function as other virtual network services do. Instead, they represent software packages that perform similar intents. However, instead of being installed on dedicated hardware or equipment running inside a data center, these applications run entirely within the data center's servers.

Virtual network functions have gained significant traction in the marketplace. They are a must-have for organizations building next-generation service architectures and provide a platform for delivering secure, agile services while enabling state-of-the-art business models at lower cost and flexibility than traditional monolithic hardware-centric legacy systems.

Adding network functions to a data center, like firewalls, switching, DHCP, DNS, WAN optimization, and load balancers, adds cost and complexity you can avoid. Businesses can move these into software-based virtual network functions that separate each function from the underlying proprietary hardware and keep them operating, regardless of any failures of the physical environment around them.

The need for VNFs

Although they are critical to business operations, traditional physical networks are relatively stagnant by modern data center standards due to the hardware-centric nature of their design and insufficient programmability. Generally, network orchestration includes deploying network resources via a command-line interface (CLI) or basic scripting tools.

Such an infrastructure consists of private hardware and proprietary software that’s tightly linked. All of this proprietary equipment results in a network that’s complicated, inflexible, and costly to acquire and operate.

But things are changing fast. There is a significant industry movement to automate provisioning and configuration of applications and infrastructure on-premise and in the cloud with the new wave of private and public infrastructure-as-a-service offerings.

This trend is leading to a new paradigm of comprehensive IT automation. This automation aims to enable IT organizations to dynamically provision any application or connectivity from a central control center at any location, providing business agility. This trend is also driven by the desire to reduce operational costs, improve performance through automation, and simplify network management by minimizing the amount of software deployed.

The need for network programmability and agility is pushing the industry forward. Telecom service providers and other large enterprises are adopting virtualization technologies, such as SDN and NFV, to achieve ever-higher levels of productivity and ROI.

Open-source software is at the heart of the migration to a flexible, dynamic, and programmable enterprise cloud services infrastructure. This is based upon standard hardware platforms deployed in a software-defined data center (SDDC).

The introduction of SDN and NFV architectures places a lot of control over the network in the hands of the enterprise. But these architectures are just part of the solution. A critical component of network programmability that is often overlooked is an architectural construct referred to as virtual network functions.

VNFs are virtualized network services that allow higher-level programmability by encapsulating an entire physical or software-defined layer within a virtual package. They are capable of delivering network services, rather than hardware appliances like routers or switches. The idea behind using VNFs is to help customers build out their networks with tools that offer more flexibility, better security, and lower costs than traditional hardware appliances.

VNFs bridge the gap between a traditional telecom network and a software-defined network. The transformation involves moving proprietary hardware and tight APIs for hardware interfaces to common cloud infrastructure and open interfaces with external applications. The VNF model represents a shift from vertically integrated, closed systems to an open, converged infrastructure that allows flexibility in IT service delivery.

How do virtual network functions work?

A virtual network function is a standardized grouping of hardware and software components that perform a single service function unit in a layered network model. VNFs operate as software-only virtual machine instances on standard hardware. For example, a routing VNF implements all of the operations of a router but runs in software-only mode on generic hardware.

Each VNF has its own operating system (OS) instance. When compared to a containerized environment, a VM instance can have a slow start time. Application functionality for each VNF is kept entirely in the VM. This allows different threads to communicate with each other with little overhead.

Both NFV and VNF virtualization enable NFs to be implemented in a generic manner independent of the underlying device. VNFs can be operated in any VM environment, including branch offices, the cloud, and data centers.

Such an architecture enables you to:

• Place network services in the best place to provide adequate security. For example, a business can install a VNF firewall in a branch office instead of incurring the inefficiencies of an MPLS connection to hairpin traffic via a faraway firewalled data center.
• Improve application performance. For example, businesses can use a VNF for security or traffic prioritization. The network traffic is sent through the most direct route between the user and the cloud application.

VNFs are managed and coordinated as part of the network functions virtualization infrastructure. VNFs are often executed on VMs managed by operators utilizing industry best practices and VM orchestration tools. VM-based VNFs run on commercial off-the-shelf (COTS) servers and are surrounded by a guest OS/kernel, hypervisor, host OS/kernel, and network I/O. The most common hypervisors include OpenStack and VMware.

Except for performance and scalability, VNFs duplicate many of the capabilities and features found in physical network functions (PNFs), subject to the necessary modifications for operation in virtual settings.

VNFs can also work flexibly with other VNFs in the cloud, allowing customers to manage their resources more effectively. As a software application, a virtual server may host multiple VNFs, which can be switched on and off as needed. These VNFs are linked together like building blocks through a process called service chaining. Although the concept is not new, VNF technology shortens and simplifies service chaining.

VNF vs. CNF

Cloud-native network functions (CNFs) are a popular topic in network design. CNFs employ containers as the foundation for network functions and will thus substitute the most widely used standard today, virtual network functions. Before dwelling on CNFs, it is imperative to understand the hurdles telcom giants face when using legacy VNFs.

VNF: The good, the bad, and the ugly

Virtual network functions are a software implementation of NF devices packed in a VM that runs on top of COTS NFV infrastructure. VNFs are an essential component of NFV. The foundation of NFV is to virtualize network services and make them software-based to decrease costs, obtain complete control over network operations, and gain agility and flexibility. The bulk of NFV activities focus on servicing VNFs on NFV infrastructure to deliver new customers.

Vendors and open-source organizations offer VNFs to service providers that are converting their infrastructure to NFV. There may be many VNFs that work together to produce a single NFV service. This complicates the general NFV objective of agility because VNFs from various suppliers must be deployed in NFV infrastructure with a distinct operating architecture.

VNFs created by different manufacturers have distinct approaches for full deployment in an existing NFV environment. Onboarding VNFs is difficult due to a lack of defined protocols for comprehensive management, from development to deployment and monitoring.

CNF: Moving towards containerization

Current software development innovation makes any system cloud-native. This means apps are API-driven, microservices oriented, containerized, and dynamically managed. Cloud-native features enable developers to create a finished product at record speed while automation manages all software components. 

With cloud-native features, organizations benefit from improved flexibility, scalability, dependability, and portability by employing centralized and dispersed sites for applications. Moving beyond virtualization to a completely cloud-native architecture boosts the efficiency and agility required to quickly deliver novel, unique offerings that markets and consumers want.

A cloud-native VNF, also known as cloud-native network function (CNF), is a VNF intended for the developing cloud environment. CNFs operate in containers rather than virtual machines. The life cycle is controlled by a container orchestration system, such as Kubernetes, and employs cloud-native orchestration principles.

CNFs are developed and configured to run within containers. This containerization of network architectural components enables many services to run on the same cluster and makes for easier onboarding of pre-decomposed apps – all while dynamically routing network traffic to the appropriate pods.

The usage of containers rather than VMs is a key differentiating characteristic of the cloud-native approach. Containers enable users to bundle software (apps, functions, or microservices) with all of the files required to operate them. They also allow sharing access to the OS and other server resources. This technique makes it simple to move the enclosed component across different environments while keeping complete functionality.

By putting network functions into containers, CNFs address some of the primary constraints of VNFs. The containerization of network components allows businesses to control how and where functions execute across nodes in the network.

Developing cloud-native VNFs is a cost-effective solution for businesses, and having all cloud-native qualities in VNFs is a revolution in software development. Self-management and scalability are among the most significant differences between cloud-native VNFs and traditional VNFs.

Benefits of virtual network functions

Virtual network function is a paradigm that's sweeping the networking industry – and rightfully so. VNF is on the rise due to its useful functions in promoting network agility and dynamic service management through hardware and software abstraction and dynamic workload provisioning. VNF is an extension of network virtualization that includes functionalities for a particular job.

Here are some major benefits of using VNF:

• Faster service life cycle: VNFs can be generated and deleted on the go. The lifespan of a VNF is shorter and more dynamic since functionalities are frequently added and readily provided using automated software tools that do not require onsite involvement.
• Reduced use of resources: Originally, businesses manually deployed new services and network functionalities. Network engineers configured them in tandem with their dedicated hardware devices or boxes. VNFs virtualize such functions, allowing for faster deployment of additional functions as VMs. Virtualization removes the requirement for dedicated hardware.
• High availability and scalability: With a single click, businesses can download, transfer, upgrade, delete, activate/deactivate, and scale up/down any network location with the help of VNFs. This provides an infrastructure that’s highly available and easily scalable.

Challenges of virtual network functions

VNF is designed to solve networking problems that exist in physical environments. VNFs are developed using software-based switching, routing, encryption, and data storage solutions for a particular business need. Meaningful use is continuously growing, and so are the use cases for VNF.

VNF is changing the landscape of network-related industries and providing opportunities to build new services. However, several challenges need to be addressed to develop further and utilize this technology.

Here are some major challenges of using VNF:

• Management and orchestration: One of the main difficulties of a completely virtualized network architecture is managing and orchestrating (MANO) resources by VNFs. VNFs are deployed in large VM increments. It’s challenging to optimize VNF resource allocations to satisfy traffic workload expectations. This leads to over-provisioning and resources remaining inactive. Due to a lack of appropriate VNF traffic engineering skills, the allocation of VM resources to cloud-ready apps and server growth is limited.
• Dependencies on kernel network features: To execute the necessary function, VNF implementation may rely on specific kernel changes or "hacks." This adds complexity to the hybrid infrastructure.

Virtualization to the rescue

Virtual network functions are one of several evolving architectures changing the way the technology sector creates, delivers, and maintains network applications. It's essential to keep up with these changes because your network infrastructure directly impacts your organization's capability to deliver high-quality services quickly, securely, and at scale.

The world is rapidly changing. Upgrade your business infrastructure to run on virtual machines using network virtualization.