Unveiling Virtual Network Functions (VNFs): Transforming Network Services

By Chiradeep BasuMallick - Published on March 15, 2024
Virtual Network Functions

Virtual network functions (VNFs) are defined as virtual forms of network services like firewalls and routing, implemented as software instances instead of proprietary hardware appliances. Read on to learn how network services have evolved and why VNFs signal a vital shift in the right direction.

The Evolution of Network Services

Until the 1990s and early 2000s, network services were monolithic, rigid structures. There were hardware-based solutions dedicated to a specific function like routing, switching, or firewalling. These traditional network functions were the backbone of communication infrastructures but came with several limitations.

In the past, scaling up your network meant scaling up physically.

Need more capacity? You’d have to invest in more hardware and physical space and spend precious time configuring and integrating these new components into your network. It was a cumbersome process.

Then came the revolution: network virtualization. You could now abstract your network functions from the hardware, making them more flexible, scalable, and efficient. Virtual network functions, or VNFs, emerged as the primary drivers of this transformation. Instead of relying solely on dedicated hardware, you could spin up virtual instances of network functions on commodity hardware.

So, what drove this seismic shift towards VNFs?

The answer lies in agility, scalability, and cost-effectiveness. With VNFs, you have the power to deploy new services and scale your network on the fly. Need more bandwidth? Want to roll out a new security feature? VNF helps you adapt to evolving demands in real-time without any challenges or setbacks.

With time, several types of VNFs have evolved to handle different kinds of network services:

  • Firewall (vFW): Filters and controls network traffic based on security policies to prevent unauthorized access and protect the network from threats.
  • Load balancer (vLB): Distributes incoming network traffic across multiple servers or resources to optimize performance and ensure even workload distribution.
  • Router (vRouter): This device directs traffic between network segments or destinations based on routing protocols, facilitating efficient data transmission.
  • Switch (vSwitch): This device forwards data packets between network interfaces or virtual machines within the same network segment, enabling communication and supporting network features.
  • WAN optimization (vWAN optimization): Improves WAN performance by reducing latency, optimizing bandwidth usage, and accelerating data transfer rates.
  • Intrusion detection system/intrusion prevention system (IDS/IPS): Monitors network traffic for signs of malicious activity and takes action to prevent security breaches.
  • Deep packet inspection (DPI): Analyzes the contents of network packets at the application layer to identify and classify traffic based on protocols, applications, or content types.
  • Virtual private network (VPN): Establishes secure, encrypted connections over public networks to enable remote users or branch offices to access corporate resources securely.

Why VFN? Virtual Network Functions vs. Traditional Networks

Now, how do virtualized functions compare to traditional ones? To put it simply, traditional network functions are like heavyweight boxers—powerful but a bit slow on their feet. They’re tied to specific hardware, which limits their flexibility and scalability. And if you ever want to upgrade, you’d have to prepare for downtime and hefty expenses.

On the other hand, virtualized functions are like nimble gymnasts. They’re lightweight and agile and can perform feats that traditional functions can only dream of. Since they’re decoupled from the hardware, you can easily spin them up, tear them down, and move them around your network. Need to scale horizontally? Just add more virtual instances. It’s that simple.

In a nutshell, the evolution of network services is all about embracing change and spearheading innovation. VNFs represent the next frontier in network architecture, offering unparalleled flexibility and efficiency.

How Do VNFs Work? 5 Crucial Steps

VNFs operate within a network environment as software-based instances that replicate the functionality of traditional network appliances. Their job is to process and manipulate network traffic through the infrastructure. Here’s a breakdown of the steps involved:

1. Packet arrival and classification

When a packet enters the network, it traverses various network nodes until it encounters a VNF. The VNF’s initial task is to classify the packet based on its header information. This classification determines the type of processing and treatment the packet will undergo.

The waiting VNF could be anything from firewalls and load balancers to routers and WAN accelerators, all packaged up as virtualized instances.

2. Packet inspection and processing

Once classified, the packet is inspected and processed by the VNF. This means analyzing the packet’s contents, payload, and metadata to enforce policies, apply security measures, or perform any necessary transformations based on predefined rules and configurations.

3. Optimization and processing

Once the packet has been thoroughly vetted and sanitized, it’s time for optimization. This is where your VNFs work their magic to ensure that the packet reaches its destination most efficiently. They might compress data, prioritize certain types of traffic, or even reroute the packet through a different path to avoid congestion.

4. Packet routing

After processing and optimization, the VNF determines the appropriate routing path for the packet based on network policies and traffic engineering considerations. It then forwards the packet along the designated path towards its intended destination. Thanks to the agility and intelligence of your VNFs, they’ve been polished to perfection, ensuring a smooth and seamless experience for you and your users.

5. Monitoring and analytics

Throughout the packet processing lifecycle, VNFs generate telemetry data and performance metrics that are collected and analyzed for network monitoring, troubleshooting, and optimization. This visibility into VNF operations enables network administrators to maintain network health, detect anomalies, and fine-tune network configurations as needed.

VNFs abstract network functions from dedicated hardware appliances, enabling flexible, scalable, and automated network operations.

What is the VNF Architecture? Components and Deployment Models

The typical VNF architecture must behave like a well-oiled machine, finely tuned to deliver high-performance network services with maximum efficiency. At its core, it has a set of essential components that work together seamlessly to bring virtualized network functions to life.

First is the VNF manager, the central nervous system powering the environment. The VNF manager handles the lifecycle management of your VNFs, from instantiation to termination and everything in between. It orchestrates VNF instances, configures their parameters, and ensures they play nice with the rest of your network ecosystem.

Next is the virtualized infrastructure manager (VIM). The VIM is responsible for provisioning and managing the virtual resources that underpin your VNFs, including compute, storage, and networking resources.

Finally, you have the VNF forwarding graph (VNFFG). The VNFFG defines the logical topology of your VNFs and the traffic flow between them. It’s like a blueprint telling your packets where and how to get there. By defining the order and relationship of VNFs in the graph, you can orchestrate complex service chains tailored to your specific network requirements.

As for deployment models, CIOs and network managers can choose one of the following options:

  • Single VNF instance: This is your basic vanilla deployment model. You spin up a single instance of a VNF to handle a specific network function, like routing or firewalling. It’s simple and straightforward and does the job without frills or fuss.
  • Multiple VNF instances: Sometimes, one VNF just isn’t enough. In this model, you deploy multiple instances of the same VNF to handle increased traffic loads or provide redundancy and high availability. This model ensures fault tolerance by distributing traffic processing across multiple VNF instances.
  • Service chaining: Service chaining involves the sequential deployment of multiple VNF instances to create custom service chains tailored to specific network requirements. Each VNF instance performs a distinct network function, and traffic flows through the chain according to predefined policies and configurations.

In Conclusion: What is the Future of VNFs?

Virtual network functions form the foundations of future network innovation. With the rapid rise of cloud computing, enterprises are moving towards cloud-native network functions (CNFs), the next generation of virtualization. This trend hinges on the bold pathway paved by VNF technology, which untethered network functions from expensive hardware dependencies.

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Chiradeep BasuMallick | Chiradeep BasuMallick is a content marketing expert, startup incubator, and tech journalism specialist with over 11 years of experience. His background includes advertising, marketing communications, corporate communications, and content marketing. He has collaborated with several global and multinational companies. Presently, he runs a content marketing startup in Kolkata, India. Chiradeep writes extensively on IT, banking and financial services, healthcare, manufacturing, hospitality, financial analysis, and stock markets. He holds a literature and public relations degree and contributes independently to leading publications.

Chiradeep BasuMallick | Chiradeep BasuMallick is a content marketing expert, startup incubator, and tech journalism specialist with over 11 years of experience. His backgr...

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