Creating More Agile and Upgradable Networks with a Controller-Based Architecture

All enterprises are in a constant state of digital flux, striving to keep existing business processes running efficiently while pushing to build new applications to satisfy customer and B2B requirements. Underlying these initiatives is the enterprise network, connecting employees and applications to the world of customers and business partners. From the data center to wired and wireless campus offices to distributed branch sites and cloud applications, the network unifies communications, collaboration, and commerce.

But the network too is in the throes of digital flux. The network infrastructure devices—switches, routers, wireless access points (APs)—are frequently in need of upgrades to add new capabilities and software fixes and apply security patches to protect against new threats. In other cases, where a business requires extremely high availability—such as a securities trading nexus—upgrades to the network infrastructure may be few and far between and only high-priority security patches are applied over the span of years. In addition, different divisions of the enterprise may require variants of the core network operating system (NOS) in order to fine-tune performance for different business operations, mandated uptime, and traffic types.

Keeping the constellations of routers, switches, and access points up to date with the latest versions and variants of the NOS and security patches is a monumental task for budget-constrained IT organizations. The traditional upgrade path is an extremely manual process: from finding the correct gold version of NOS image, downloading it, testing on each platform, installing on each component, and manually comparing the previous network status to the upgraded state—and potentially rolling back the upgrade in case of unexpected issues. One. Box. At. A. Time. The process is often so complex that IT dedicates months to evaluate and test an upgrade before deploying it. Meanwhile business needs may go unmet as changes to the network are frozen, awaiting new capabilities from an upgrade.

As organizations seek to rapidly adopt new technologies and launch digital transformation projects—IoT, edge computing, mobile applications—and prepare for Wi-Fi 6 and 5G traffic increases, the network must be able to change frequently and on-demand to keep up with business needs. The old ways of manually managing software for thousands of network components simply will not suffice to keep the enterprise competitive.

The answer to this challenge lies in evolving the network infrastructure to a Controller-Based Architecture. I first touched on this topic in a previous Cisco network architecture blog post: From Controllers to Multi-Domain: 7 Pillars of Intent-Based Networking. In this post, we will take a much deeper dive into the benefits of controller-based networking.

What is a Controller-Based Network?

Cisco introduced the idea of Intent-Based Networking as a software-defined architecture that interprets business requirements—intents—and translates them into network actions such as segmentation, security policies, and device onboarding. Controllers are key to bringing purposeful intelligence into an Intent-Based Network. Controllers act as intermediaries between human operators specifying intents, and all the switches, routers, and access points that provide the required connectivity.

Controllers, such as Cisco DNA Center and Cisco vManage, translate intents into configurations and policies that are downloaded to network infrastructure devices—switches, routers, access points—that provide the connectivity to computers, mobile devices, and applications. Controllers provide visibility into the network by actively monitoring network nodes, analyzing telemetry, latency, Quality of Service levels, and error data in real time, and reporting statistics, alerts, and anomalies to IT managers. In turn, this provides insights into how the network has been functioning, along with its current state to ensure that the intents are being accomplished. Insights into network history and current states play a critical role in managing and automating the maintenance and upgrade processes.

Network Process Automation at Scale

With thousands of switches, routers, and APs requiring management, automating as many network processes as possible reduces the workload of IT as well as the chances of human error. In particular, controllers are key to automating enterprise-wide upgrade and patching processes at scale. Instead of upgrading individual switches and routers one at a time, an upgrade intention is set at the controller level that automates the entire process of upgrades in stages.

• Controllers can run network-wide checks—available storage space, uptime criticality, version control— to ensure readiness before upgrading the image for each type and location of device.
• Controllers automatically search and download images from Cisco Cloud repositories based on feature sets and network device types currently in use. 
• The correct golden images are automatically staged to each switch and router, eliminating the need for an operator to manually copy and monitor the progress one at a time.
• Based on the uptime criteria of each section of the network, the actual upgrades are scheduled for the most appropriate time and automatically started.
• Controllers perform a pre-check of network devices to catalogue current network operating statistics such as number of clients, number of ports in use, and traffic levels.
• During the post-check phase, controllers observe the impact of the upgrades on the network by comparing pre-check statistics with post-upgrade statistics to ensure that the network is operating as expected.
• IT can add customized lists of pre- and post-check items—such as ensuring applications (cloud and on-premise) are reachable and responding appropriately—to run before and after the upgrade.
• Should network operating parameters be negatively impacted, the controllers can automatically initiate a rollback of the update to the previous state.

These general steps outline a series of programmable events that are ultimately driven by the intents of the organization filtered through IT and the controllers. Controllers provide the ability to change an organization’s structure and operations much faster. For example, an enterprise can react more quickly when preparing for a new application being rolled out to hundreds of branch sites and the network needs an upgrade to local branch routers to ensure application quality of experience. Automating the updates from a central management controller saves time, travel, and quickly prepares the branches for new business processes.

Automation at scale becomes even more important when dealing with the scope of IoT network infrastructure. With a geographically distributed network of nodes that connect thousands of IoT devices in the field and factory, being able to reach out from a central cloud management controller and apply segmentation rules and security policies to protect device connections is a very practical method of securing them. In cases like these, centralized controller automation eliminates thousands of hours of technician truck rolls.

Open Controller APIs Extend Programmability for Third-Party Automations

Automated updates to routers, switches, and access points are only one of the ways a controller-based network increases enterprise speed and agility. With an open set of APIs, controllers can communicate with higher-level applications and services such as Application-Aware Firewalls and Internet Protocol Address Management (IPAM) tools. To help automate managing the network’s health and support, IT can also employ APIs to program controllers to send network device analytics and events to an IT Service Management (ITSM) system. In turn, the ITSM can send commands and approvals to controllers to kick-off specific actions, such as times to schedule upgrades on the network. The two-way communication through APIs provides IT with a flexible method to minimize hands-on technical operations and free up valuable talent for other projects.

Controllers Are Foundational for Building Intent-Based Networks

As the examples in this post show, controllers are the basis for implementing Intent-Based Networks that intelligently monitor, pinpoint abnormal operations, and proactively apply remedies to keep the network optimized for performance and security. They significantly reduce the hands-on manual labor traditionally required for upgrading and patching complex networks. Controllers automate pre-checks, post-checks, and rollbacks to ensure network continuity and protect against human error. Automation of these processes frees up IT talent to work on business transformation initiatives while making the network easier to change to meet new business needs.

In future posts, I’ll double-click on the other pillars of Intent-Based Networking and their benefits to your organization. In the meantime, you may be interested in additional information on Cisco controllers, as well as a recent blog.

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