What is WAN? Wide Area Networks Explained

Apr 26, 2021

Ways to Connect Your Distributed Business Locations Reliably, Securely and Cost-Effectively

The concept of a Wide Area Network, or WAN, traces its roots back to the 1950s when the U.S. Air Force interconnected sites in the Semi-Automatic Ground Environment (SAGE) radar defense system using dedicated phone lines, telephones and modems.

Technology has come a long way since then, but the business challenge remains the same: large, multisite organizations need to share access to applications, services and other resources among headquarters, data centers and branch offices – reliably, securely and cost-effectively – whether these locations are across the country or around the world.

What is a Wide Area Network (WAN)?

Essentially, a WAN is a geographically distributed network that joins multiple Local Area Networks (LANs) as one large, private network. LANs are computer networks within a single office, building, or small campus. A WAN interconnects multiple LANs to transmit information over longer distances and among larger numbers of endpoints.

Think of a multisite corporation with offices throughout the world. A WAN that interconnects these geographically dispersed locations enables employees, wherever they sit, to access resources, applications and communications from the corporate data center.

Wide Area Network: How It Works

Wide Area Network Map

Other WAN examples include a network of bank ATMs or a university with college campuses spread throughout a state. In fact, one of the first WANs, ARPANET, connected universities in California and Utah and is the precursor to what we now know as the internet. Unlike the internet, however, WANs are private networks designed for sharing private internal resources.

What are the Benefits of Wide Area Networking?

WANs deliver a range of benefits, enabling multilocation organizations to:

  • Share data across all devices connected to the network, instantly synchronizing updated information across branch offices.
  • Centralize IT as all employees tap into the same infrastructure. You only have to invest in email and file servers once, and centralization simplifies backup and maintenance.
  • Improve data security with S encryption and other measures to keep your data safe and compliant with regulations like HIPAA.
  • Increase bandwidth as data traverses over leased or private lines instead of broadband Internet links, providing low- latency, higher-speed connections without throttling or data caps.
  • Guarantee uptime with a provider Service Level Agreements (SLA) and on-call support.
  • Save costs by consolidating data traffic across the same connections and reducing travel with online collaboration tools.


What are Types of Wide Area Network Technologies?

There have been multiple WAN technologies used over the years, such as Asynchronous Transfer Mode (ATM) and Frame Relay, which have been superseded by newer technologies – namely Multiple Protocol Label Switching (MPLS) and Carrier Ethernet.

  • MPLS is a protocol, not a service, which supports Layer 2 and 3 networks. However, when used in conversations about WANs, it typically refers to Layer 3 IP Virtual Private Networks (VPNs). MPLS is used to create point-to-point, multipoint or meshed networks over copper, fiber and fixed wireless connections.
  • Carrier Ethernet is a Layer 2 protocol that supports point-to-point, hub-and-spoke, or meshed networks over copper, fiber and fixed wireless connections.


What is a Software-defined Wide Area Network (SD-WAN)?

SD-WAN is a newer approach to building multisite networks. While MPLS or Carrier Ethernet are underlay networks, SD-WAN is an overlay network.

  • Underlay networks – physical networks responsible for packet delivery
  • Overlay networks – virtualized network layers on top of the physical network created by software, which often provides additional benefits



Using software, SD-WAN creates an overlay network that enables providers to configure, manage, monitor and secure the WAN remotely. This includes edge devices and traffic flows that must be set up manually in a traditional WAN’s hardware. With software defining the network characteristics, SD-WAN also enables the use of low-cost broadband as corporate WAN connections. Further, it supports hybrid SD-WAN and MPLS WANs, which can be a good option for companies that want to reduce WAN costs at branch offices but want to keep their MPLS connections between data centers.

Which Wide Area Network Design is Best for your Business?

The best WAN for your organization depends on your specific requirements, including applications, bandwidth, security, uptime, cost and more. Here are some examples:

  • When Quality of Service (QoS) is paramount, such as with real-time video or mission-critical data traffic, MPLS may be your best option.
  • When you need a cost-effective WAN to connect data centers or remote offices, consider Ethernet Multipoint-to-Multipoint.
  • When you have high data traffic between a hub site and multiple remote sites, take a look at Ethernet Point to Multipoint network with automatic failover to a secondary connection, then SD-WAN is a great choice.

As with any data network deployment, seek expert advice to evaluate your needs and your options. You may find a hybrid wide area network solution that combines different approaches is the best fit.


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