Intent-Based Networking can only be understood if we understand what Intent is. Purpose makes the definition of intent easier to understand because it is a synonym. Intentions or purposes vary from person to person, department to department, and organization to organization. It is possible for an organization to provide the best in class software to schools or to provide the best phones available. The purpose of a business process can be to fulfill the described task as efficiently as possible. It is, of course, potential for a person to have multiple intentions or purposes. Generally, intent or purpose describes a goal to be achieved.

Example: Cisco DNA

As a network infrastructure built on Cisco DNA, IBN describes how to manage, operate, and enable a digital business using the network. An intent within the industry is translated into a network configuration that fulfills that intent. This is accomplished by defining the intent utilizing a set of (repetitive) steps. Cisco DNA is used to approach networks using all aspects of IBN (design principles, concepts, etc.).

The lack of Agility

Intent-based networking is not just hype; we see many intent-driven networks already with many SD WAN overlay roll-outs. It is a necessary development; from a technology standpoint, it has arrived. However, cultural acceptance will take a little longer. Organizations are looking to modernize their business processes and their networks.

Yet, traditional vertically integrated monolithic networking solutions prohibit the network from achieving agility. This is why we need intent-based networking systems. So, what is intent-based networking? Intent-based networking is where an end-user describes what the network should do, and the system automatically configures the policy. It uses declarative statements instead of imperative statements. 

Converts the What into How

You are telling the network what you want to accomplish, not precisely what to do and how to do it, i.e., tell me what you want, not how to do it, all of which gets translated behind the scenes. Essentially, intent-based networking is a piece of open networking software that takes the “what” and converts it into the “how.” The system generates the resulting configuration for design and device implementation.

The system is provided with algorithms that translate business intent into network configurations. Humans can not match the speed of algorithms, and this is key. The system is aware of the network state and can ingest real-time network status from multiple sources in a transport and protocol-agnostic way.

The Desired State

It adds the final piece of the puzzle by validating in real time that the intent is being met. The system continuously compares the actual to the desired state of the running network. If the desired state is unmet, corrective actions such as modifying a QoS policy or applying an access control list (ACL) can occur. This allows for a closer alignment between the network infrastructure and business initiatives and maintains the network’s correctness.

Related: Before you proceed, you may find the following posts helpful.

1. Network Configuration Automation
2. Distributed Systems Observability
3. Reliability in Distributed Systems
4. Container Networking
5. Overlay Virtual Networking

Back to basics: Intent-Based Networking

Learning more about intent-based networking is essential to understanding it. An intent is a brief description of the purpose and a concrete, predetermined set of steps that must be executed to (successfully) achieve the Intent. This principle can also be applied to the operation of a network infrastructure. The Intent and its steps precisely describe what needs to be done on the network to accomplish a specific task. 

For example, the application is migrating to the cloud. In this case, the Intent or steps may include the following. First, take the existing access policy for that application from the data center policy, transform the policy into an application policy for Internet access, deploy the procedure on all perimeter firewalls, and change the routing for that application to the cloud.

Critical Principles of Intent-Based Networking:

1. Translation: Intent-based networking automatically translates high-level business objectives into network policies and configurations. By understanding the desired intent, the network infrastructure can autonomously make the necessary adjustments to align with the organization’s goals.

2. Automation: Automation is a fundamental aspect of IBN. By automating routine network tasks, such as provisioning, configuration, and troubleshooting, network administrators can focus on strategic activities that add value to the organization. Automation also reduces the risk of human error, leading to improved network reliability and security.

3. Assurance: IBN provides continuous monitoring and verification of network behavior against the intended state. By constantly comparing the network’s current state with the desired intent, IBN can promptly identify and mitigate any configuration drift or anomalies. This proactive approach enhances network visibility, performance, and compliance.

Benefits of Intent-Based Networking:

1. Simplified Network Management: With IBN, network administrators can easily manage complex networks. By abstracting the complexity of individual devices and focusing on business intent, IBN simplifies network operations, reducing the need for manual configuration and troubleshooting.

2. Enhanced Agility and Scalability: IBN enables organizations to respond quickly to changing business requirements and effortlessly scale their networks. By automating network provisioning and configuration, IBN supports rapid deployment and seamless integration of new services and devices.

3. Improved Network Security: Security is a top concern for modern networks. IBN offers enhanced security by continuously monitoring network behavior and enforcing security policies. This proactive approach reduces the risk of security breaches and enables faster threat detection and response.

4. Optimized Performance: IBN leverages real-time analytics and machine learning to optimize network performance. By dynamically adjusting network configurations based on traffic patterns and user behavior, IBN ensures optimal performance and user experience.

Example Solution: Cisco SD-Access

The Cisco SD-Access digital network evolution transforms traditional campus LANs into intent-driven, programmable networks. Campus Fabric and DNA Center are Cisco SD-Access’ two main components. Creating and monitoring the Cisco Campus Fabric is automated and assured through the Cisco DNA Center.

Cisco Campus Fabric Architecture
In Cisco SD-Access, fabric roles and terminology differ from those in traditional three-tier hierarchical networks. To create a logical topology, Cisco SD-Access implements fabric technology using overlay networks running on a physical network (underlay network).

Underlay networks are traditional physical networks that connect LAN devices such as routers and switches. Their primary function is to provide IP connectivity for traffic to travel from one point to another. Due to the IP-based underlay, any interior gateway protocol (IGP) can be utilized.

Overlay and Underlay Networking

Fabrics are overlay networks. In the IT world, Internet Protocol Security (IPsec), Generic Routing Encapsulation (GRE), Dynamic Multipoint Virtual Private Networks (DMVPN), Multiprotocol Label Switching (MPLS), Location Identifier Separation Protocol (LISP), and others are commonly used with overlay networks to connect devices virtually. An overlay network is a logical topology that connects devices over a topology-independent physical underlay network.

Forwarding and control planes are separated in overlay networks, resulting in a flexible, programmable, and scalable network. To simplify the underlay, the control plane and data plane are separated. As the control plane becomes the network’s brain, it allows faster forwarding and optimizes packets and network reliability. As an underlay for the centralized controller, Cisco SD-Access supports building a fabric using an existing network.

Underlay networks can be automated with Cisco DNA Center. As a result, it is helpful for new implementations or infrastructure growth since it eliminates the hassle of setting up the underlay. For differentiation, segmentation, and mobility, overlay networks often use alternate forwarding attributes in an additional header.

Networking Complexity

Networks continue to get more complex as traffic demands increase. While software-defined networking (SDN) can abstract the underlying complexities, we must consider how we orchestrate the policy and intent across multi-vendor, multi-domain elements.

To overcome complexity, you have to abstract. We have been doing this with tunneling for decades. However, different abstractions are used at the business and infrastructure resource levels.

At a business level, you need to be flexible as rules will change and must be approached differently from how the operating system comes modeling resources. We must make new architecture decisions for this, as it’s not just about configuration management and orchestrations. None of these can look at the network state, which we need to do.

For this, we need network intelligence. Networks are built and managed today using a manual approach without algorithmic validation. The manual process of networking will not be viable in the future.  Let’s face it: humans make mistakes.

There are many reasons for network outages, ranging from software bugs and hardware/power failure to security breaches. All of which comes from a lack of implementing network security. But human error is still the number one cause. We are inhibited by manual configuration. Intent-based networking eliminates this inhibition.

The traditional approach to networking

In the traditional network model, there is a gap between the architect’s intent and what’s achieved. Not just for device configuration but also for achieved runtime behavior. Until now, there has not been a way to validate the original intent or to have a continuous verification mechanism.

Once you have achieved this level of assurance, you can focus on business needs and not be constrained by managing a legacy network. For example, Netflix moved its control plane to the cloud and now focuses all its time on its customer base.

We have gone halfway and spent billions of dollars on computing storage and applications, but the network still lags. The architecture and protocols have become more complex, but the management tools have not kept pace. Fortunately, now, this is beginning to change.

Software-defined networking; slow deployments

SDN shows great promise that could release networking, but deployments have been slow. Primarily down to large cloud-scale organizations with ample resources and dollars. But what can the rest of the industry do if we do not have that level of business maturity?  Intent-based networking is a natural successor to SDN, as many intent-based vendors have borrowed the same principles and common architectures.

The systems are built on the divide between the application and the network infrastructure. However, SDN operates at the network architecture level, where the control plane instructs the data plane forwarding node. Intent-based systems work higher at the application level to offer true brownfield network automation.

SDN and SD-WAN have made considerable leaps in network programmability, but intent-based networking is a further leap to zero-touch self-healing networks. For additional information on SD-WAN, including the challenges with existing WANs, such as lack of agility with BGP ( what is BGP protocol in networking ) and the core features of SD-WAN, check out this SDWAN tutorial.

Intent-Based Networking Use Case

The wide-area network (WAN) edge consists of several network infrastructure devices, including Layer 3 routers, SD-WAN appliances such as Viptela SD-WAN, and WAN optimization controllers. These devices could send diagnostic information for the intent-based system to ingest. The system can ingest from multiple sources, including a monitoring system and network telemetry.

As a result, the system can track application performance over various links. Suppose there is a performance-related problem, the policies are unmet, and application performance degrades.

In that case, the system can take action, such as rerouting the traffic over a less congested link or notifying a network team member. The intent-based system does not have to take corrective action, similar to how IDS/IPS is deployed. These devices can take disciplinary action if necessary, but many use IDS/IPS to alert.

Looking deeper on intent-based networking systems

The intent-based architecture combines machine learning (ML), cognitive computing, and deep analytics, providing enhanced levels of automation and programmability through an easy-to-use GUI. Combining these technologies allows you to move from a reactive to a proactive system.

ML, a sub-application of artificial intelligence (AI), allows intent-based systems to analyze and learn from data automatically without explicit programming. Therefore, it enables systems to understand and predict the data for autonomous behavior. Intent-based networking represents a radical new approach to network architecture and takes networking to the next level in intelligence.

It is not a technology that is going to be accepted overnight. Its adoption will be slow as, to some, a fully automated network can sound daunting, placing the faith of your business, which for many organizations is the network.

However, deploying intent-based networking systems offers a new way to build and operate networks, which increases agility, availability, and security compared to traditional networking.

Intent-based networking (IBN) is transforming the way networks are managed. By shifting the focus from device-centric configurations to intent-driven outcomes, IBN simplifies network management, enhances agility and scalability, improves security, and optimizes network performance. As organizations strive to meet the demands of the digital age, embracing this innovative approach can pave the way for a more efficient and intelligent network infrastructure.