SD-WAN – Improve Performance, Reduce Cost

SDN Software Defined Networks

Do you use IP-VPNs or MPLS? Then you know the challenges and want to know how to master them. The following article about SD-WAN describes possible solutions to simultaneously increase bandwidth and reduce cost.

Initial situation in the WAN

Branch networking, integration of mobile users of smartphones or tablet computers and the Internet of Things (IotT) are booming.

For cost reasons, in the past, you have relied increasingly on IP-based Virtual Private Network (IP-VPN) solutions. For this, you often used the public Internet and different network access technologies.

Or you invested in high-quality but cost-intensive data connections of Multiprotocol Label Switching (MPLS) services.

In both cases, the available bandwidth is important to you. And that is not always available. However, increasing bandwidth also means increasing your costs. Add to this your new applications such as Voice over IP, unified communications, video conferencing, streaming, etc., which generate higher demands on service quality than in the past. Another challenge is transnational networking with high-quality links.

What can you do to cover the ever-increasing demands without increasing costs even more?



In general, well-known technologies can cover a large part of the demands of IT departments for speed, bandwidth, and reliability. These include the following technologies:


Virtualization is already in use in the server and network area.

Virtual Local Area Network

In local area networks, you are certainly using virtual local area networks (VLANs). This interconnects groups of stations that frequently exchange data into one VLAN and blocks data transfer to stations outside the same VLAN.

Virtual Private Networks

In the wide area network (WAN), virtual private networks (VPNs) only allow the exchange of data between known subscribers (e.g. branch offices of your company and your corporate headquarter), while other users of the same public WAN service cannot join your corporate network. Permission to communicate between defined partners can be configured by the WAN service provider or defined in the terminals attached to the WAN.

Cloud Services

In recent years, operators are offering more and more cloud services. This means users receive services tailored to their needs from various sources, which can be flexibly adapted to rapidly changing requirements.


New Technologies

Major network operators introduce new technologies:

Network Function Virtualization

The operators of large networks (which usually offer public services) face several challenges. On the one hand, their infrastructure must be highly resilient and quickly deliver new services (meet customer needs quickly), and on the other hand, cost-effective solutions are needed. By virtualizing network functions (e.g., routers, switches, DNS services, etc …), then called Network Function Virtualization (NFV), the operator can rapidly deploy, customize, and operate cost-effective network functions and services. The software logic decouples the necessary network functions from the underlying hardware logic.

Software Defined Networks

The network elements of the operators of large networks are very complex. Due to the high demands on speed, manageability and power consumption, many functions are already implemented in hardware logic (in chips). However, this leads to more inflexible systems that are increasingly difficult to adapt to new market requirements. Many manufacturers now offer software solutions that improve the manageability of complex networks and their services and simplify the deployment of completely new application-specific services (e.g., video streaming, various cloud services). These so-called software-defined networks (SDN) logically separate the network control from the network components that are responsible for the data forwarding. As a result, the network elements are centrally manageable. The network intelligence is logically centralized in SDN controllers. These provide applications with an interface that makes the entire network look like a single logical switch.

For end users, one specific service on the WAN is of interest:

Software-Defined Wide Area Network (SD-WAN)

A Software-Defined Wide Area Network (SD-WAN) helps to operate and manage a wide area network infrastructure and the services offered. It separates network hardware from its control and management mechanisms (like network virtualization).

SD-WANs help to offer and use network services based on different technologies (low-cost Internet, MPLS, Ethernet, radio networks). They may identify bandwidth bottlenecks, link failures, service degradation and much more and circumvent these challenges.

A user may need an appliance to access the service. A central controller at the operator side manages all the appliances in the offices, the policies, and Quality of Service.

The services may be offered via hybrid WANs (combines MPLS, the Internet, mobile radio services, and more) or pure cloud services. SD-WANs may offer bandwidth aggregation, fault tolerance, and zero-day-provision.

What advantages does SD-WAN offer for Unified Communications solutions?

In addition to large cost savings, specific bandwidth management and individual quality of service deployments can be implemented, depending on the requirements of the applications. Traffic flows are easier to control and redirected when needed in fractions of seconds. Thus, connection interruptions are excluded. By transmitting packet duplicates (using the same path or separate paths), one can minimize packet losses and runtime differences (jitter). With a high level of automation, SD-WANs reduce the administrative effort of a solution.

Ask your provider for support of QoS for voice and/or video communication.



Book „Unified Communications Buyer’s Guide“ (in parts)


Additional information

Courseware and textbooks:

Selecting Video Conferencing Solutions

Unified Communications – Buyer´s Guide

Corporate Telephony Strategies for Enterprise Customers and Organizations

Voice over IP Technology – Part 1/2

Voice over IP Technology – Part 2/2


About the author

Ronald Schlager is an independent trainer, consultant, book author and blogger with an emphasis on communications technologies and their application.

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