Virtualization Featured Article

The Difference between SD-WAN and SD-LAN

October 30, 2017
By Special Guest
Vivek Ganti, Sr. Manager, Product Evangelism -

It’s quite shocking that human inventiveness took 20+ years to replace manual coding of networks as the primary way to configure them. To some extent, networks themselves are to blame. For years, even as enterprises themselves evolved significantly in how they ran their businesses, their networks remained stagnant- often serviced by a single MPLS provider connecting all their edge offices to their data center.

But that’s changing. We live in a world where there are more mobile devices than people. Mobile devices are everywhere and everyone has come to expect uninterrupted and ubiquitous connectivity. This puts a demand on the networks servicing them. As broadband Internet connections became cheaper, and workloads started to shift to the cloud, enterprise networks started to grapple with the increasing complexity. On the LAN side, enterprises moved from primarily wired networks to almost completely wireless networks for edge access. On the WAN, the single MPLS connection gave way to a hybrid of MPLS and broadband Internet links that not just connected various edge offices to each other and the data center, but also to the cloud as they moved their workloads there.

This wave of digital transformation also brought with it nightmares to network admins who were expected to meet the ever-growing demands of these ‘always-on’ networks and didn’t quite have the tools to do so.

Enter automation (really letting software do all the work). A software-defined way of orchestrating networks has begun sounding the death knell on the traditional way of networking. While older networking methodologies are grappling with their costly legacy of manual configuration and potentially significantly higher downtimes, newer software-defined technologies on the LAN and the WAN are unencumbered.

This shift from manual drudgery of configuring networks to orchestrating them using software that does all the heavy-lifting is already happening. Enterprises are moving away from the legacy way of configuring individual appliances on a site-by-site basis for their networks. They are embracing software-defined technologies such as SD-WAN and SD-LAN that are quickly demonstrating rapid gains in their network management costs.

Let’s talk about SD-WAN first. There are some key factors that make SD-WAN a buyable technology that can significantly benefit enterprises.

How SD-WAN Can Benefit Enterprises

  • It’s really all about application performance. SD-WAN abstracts underlying transport layer details enabling enterprises to focus on what’s important to their business goals- applications. Being able to define policies that are as easy to configure as they are to state in common language is something SD-WAN has the power to do (watch this video to see how you can even configure your network with simple voice commands!).
  • Automated connectivity is a boon to network admins. It can take days, if not weeks, for network admins to configure IPSec VPN tunnels to several sites via command line. This drudgery can be skipped with some automation built-in with software-defining the WAN.
  • WAN optimization is still very key to application performance. In a world with unlimited and inexpensive bandwidth, why do enterprises still need WAN Optimization? One word- latency.

Applications are getting smarter and lighter, but heavy data-sets still need to be uploaded and downloaded often to locations far from the source. WAN Optimization works hand-in-hand with SD-WAN to achieve the same goal- superior application performance for the end user. A complete SD-WAN solution should have WAN Optimization built-in.

  • Transformation to the cloud means more than SaaS- As workloads are moving to the cloud, so are many internal applications from physical data centers to IaaS providers. The cloud offers a variety of advantages (scale and cost being two primary ones) and connecting all the edge locations to these cloud sites ought to be easy too. But it’s not. Not without SD-WAN. Some vendors are offering a single-click connectivity to AWS and Azure. This is transformational for organizations wanting to connect their globally distributed edge offices not just to each other and their physical data centers but also cloud data centers. Being able to do so from a single centralized cloud console is even better.
  • Networks that learn, and quickly adapt are important- Application traffic today can benefit from simultaneous use of multiple transport links- automatically and dynamically choosing the best available link on a real-time basis. This dynamic path selection for application traffic is core to SD-WAN.
  • Distributed security with centralized management- A good SD-WAN solution allows enterprises to extend their security posture from the data center to all their edge offices- either via built-in perimeter firewall functionalities, or by partnering with other security vendors to form a full-fledged firewalled and secured edge office, all from a single management interface enabling the network admins and security architects to work together towards to same business goal.
  • Trust but verify- As networks become more autonomous, it becomes even more important that they perform as configured. Built-in visibility features that let network admins clearly see the what, how, where, when of network traffic form an integral part of an SD-WAN solution.

How SD-LAN Fits into the Picture

SD-LAN extends the concepts of software-defined networks to the LAN. LANs today comprise not just switches and routers, but also a plethora of wireless access points in many large enterprises. Adhering to the SDN architecture and decoupling the control plane from the data-plane, SD-LAN, like SD-WAN, makes it easy for administrators to apply business policies to the network, quickly and efficiently from one centralized location. Some key features of SD-LAN are:

  • Extending network segmentation to the LAN: Guest users need access to Wi-Fi, and being able to quickly and easily create guest portals that automatically segment their traffic based on preset policies is important. Also, in a world where BYOD is common to workplaces today, federated identity management is proving to be more cake than cherry.
  • Software-defined Radios: As with SD-WAN where traffic is sent over different uplinks based on dynamic network conditions, it is possible to use software-defined radios to switch between 2.4GHz and 5GHz based on network conditions (no. of wireless clients in each frequency band, congestion, etc.).
  • Visibility and Analytics: Visibility into the LAN is key to assure network admins that their networks perform as they configure their policies. Analytics gives organizations a deeper insight into different data points in their network and better understand behavior of their networks.

SD-WAN and SD-LAN Together

Wi-Fi access points, controllers, WAN Optimization appliances, switches, routers, edge gateways (SD-WAN) are the different pieces of the puzzle that comprise the LAN and the WAN. For all these pieces to work cohesively together as a single unified network fabric, it is imperative that the concepts of the software-defined architecture extend to both the LAN and the WAN.

To be successful in the cloud and digital world, a unified platform comprising the best of both SD-LAN and SD-WAN is necessary to deliver apps, data, and services from any public, private, or hybrid cloud across any network to any end-point.

About the Author: Vivek Ganti- Sr. Manager, Product Evangelism

Vivek currently leads Technical Marketing for Riverbed's Software-Defined WAN solution- SteelConnect. Prior to Riverbed, Vivek helped push the boundaries of Wi-Fi at CableLabs (a cable R&D consortium) focusing on Community Wi-Fi and Wireless Mesh Networks.
Before graduating top of his Master's class in Telecommunications from the University of Colorado at Boulder, Vivek studied Electrical Engineering from Manipal University, India and was a DAAD scholar at the Vodafone Chair of Mobile Communications at Dresden, Germany. Vivek is also CCNA, CCNP, and CWNA certified.

Edited by Mandi Nowitz

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