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SD-LAN vs LAN: What Are The Key Differences?

By Mathew Edwards in · Technology · June 7, 2017
In my last post, I discussed how SD-LANs help IT teams more easily design, deploy, and operate access networks. In today’s installment, I discuss in more detail what an SD-LAN is.

To understand SD-LAN, let’s backtrack a bit and look at the architecture and technologies that led to its emergence.

First, what is SDN?

Software-defined networking (SDN) is a new architecture that decouples the network control and forwarding functions, enabling network control to become directly programmable and the underlying infrastructure to be abstracted for applications and network services.

This allows network engineers and administrators to respond quickly to changing business requirements because they can shape traffic from a centralized console without having to touch individual devices. It also delivers services to where they’re needed in the network, without regard to what specific devices a server or other device is connected to.

Functional separation, network virtualization, and automation through programmability are the key technologies.

But SDN has two obvious shortcomings:

  • It’s really about protocols (rather than operations), staff, as well as end-user-visible features, function, and capabilities.
  • It has relatively little impact at the access layer (intermediary and edge switches and access points, in particular). Yet these are critical elements that define wireless LANs today.

And so, what is SD-WAN?

Like SDN, software-defined WAN (SD-WAN) separates the control and data planes of the WAN and enables a degree of control across multiple WAN elements, physical and virtual, which is otherwise not possible.

However, while SDN is an architecture, SD-WAN is a buyable technology.

Much of the technology that makes up SD-WAN is not new; rather it’s the packaging of it together - aggregation technologies, central management, the ability to dynamically share network bandwidth across connection points.

Its ease of deployment, central manageability, and reduced costs make SD-WAN an attractive option for many businesses, according to Gartner analyst Andrew Lerner, who tracks the SD-WAN market closely. Lerner estimates that an SD-WAN can be up to two and a half times less expensive than a traditional WAN architecture. SD-LAN is taking complex technology to solve complex problems, but allowing IT departments work faster and smarter in the process.

So where and how does SD-LAN fit in?

SD-LAN builds on the principles of SDN in the data center and SD-WAN to bring specific benefits of adaptability, flexibility, cost-effectiveness, and scale to wired and wireless access networks.

All of this happens while providing mission-critical business continuity to the network access layer.

Put simply: SD-LAN is an application- and policy-driven architecture that unchains hardware and software layers while creating self-organizing and centrally-managed networks that are simpler to operate, integrate, and scale.

1) Application optimization prioritizes and changes network behavior based on the apps 

  • Dynamic optimization of the LAN, driven by app priorities
  • Ability to focus network resources where they serve the organization’s most important needs
  • Fine-grained application visibility and control at the network edge

2) Secure, identity-driven access dynamically defines what users, devices, and things can do when they access the SD-LAN.

  • Context-based policy control polices access by user, device, application, location, available bandwidth, or time of day
  • Access can be granted or revoked at a granular level for collections of users, devices and things, or just one of those, on corporate, guest and IoT networks
  • IoT networks increase the chances of security breaches, since many IoT devices, cameras and sensors have limited built-in security. IoT devices need to be uniquely identified on the Wi-Fi network, which is made possible by software-defined private pre-shared keys.

3) Adaptive access self-optimizes, self-heals, and self- organizes wireless access points and access switches.

  • Control without the controllers—dynamic control protocols are used to distribute a shared control plane for increased resiliency, scale, and speed
  • Ability to intelligently adapt device coverage and capacity through use of software definable radios and multiple connection technologies (802.11a/b/g/n/ac/wave 1/wave 2/MIMO/ MU-MIMO, BLE, and extensibility through USB)
  • A unified layer of wireless and wired infrastructure devices, with shared policies and management
  • The removal of hardware dependency, providing seamless introduction of new access points and switches into existing network infrastructure. All hardware platforms should support the same software.

4) Centralized cloud-based network management reduces cost and complexity of network operations with centralized public or private cloud networking.

  • Deployment in public or private cloud with a unified architecture for flexible operations
  • Centralized management for simplified network planning, deployment, and troubleshooting
  • Ability to distribute policy changes quickly and efficiently across geographically distributed locations

5) Open APIs with programmable interfaces allow tight integration of network and application infrastructures.

  • Programmability that enables apps to derive information from the network and enables the network to respond to app requirements.
  • A “big data” cloud architecture to enable insights from users, devices, and things

As you can see, there is a lot that goes into making SD-LAN work. It’s taking complex technology to solve complex problems, but allowing IT departments work faster and smarter in the process. 

Next time I will cover how SD-LAN can help your organization, explaining how its specific features specifically serve your needs.

Mathew Edwards (@Mobility_Mat)

Mat is Manager, Product Marketing at Aerohive where he helps drive strategy and vision for Aerohive's wireless LAN solutions.