Wide-Area Network (WAN)

A wide area network (WAN) is a group of two or more interconnected local-area networks (LANs) that is not tied to any singular location. The goal of a WAN is to allow connected devices (and by extension, connected users) to access and transfer data from anywhere in the world. WANs can be public, as in the Internet (the largest WAN in existence), or they may be created for private use in a business, school, or government organization.

WAN connection types

LANs can be connected through wired or wireless means to form a WAN. The main categories of these connections are leased lines, circuit-switched networks, and packet-switched networks.

  • Leased lines are private, dedicated point-to-point connections that are leased by telecommunication providers. They have been used since the 1990s to create internal connections among distant LANs within an organization. Types of leased lines include T-1 and T-3 carriers, which are used to support MPLS and VPN connections between WANs.
  • Circuit-switched networks such as public telephone systems function through a limited number of dedicated channels that are closed when they are no longer needed. They are faster than packet-switched networks because they transmit data in real time, but can face fixed bandwidth challenges. Integrated Service Digital Network (ISDN) is an example of a circuit-switched network.
  • Packet-switched networks use virtual circuits that allow packets to be transmitted without requiring a dedicated channel. They are generally less expensive and more robust than circuit-switched networks, but can face latency issues. There are several modes of packet-switching that can be used to create a WAN:
    • X.25 is a technology standard that was introduced in the 1970s primarily to support credit card transactions and automatic teller machines (ATMs).

    • Frame Relay was developed as a simpler and more cost-effective alternative to X.25 by leveraging existing T-1 and T-3 channels.

    • Asynchronous transfer mode (ATM) is generally regarded as a faster protocol than Frame Relay because it breaks data down into a smaller, uniform cell size that can be transferred at the same speed as other types of data.

    • Multiprotocol label switching (MPLS) is the most common form of WAN linking today. It allows packets to be prioritized according to the class of service indicated by their labels. Hybrid WANs utilize a blend of MPLS and broadband/Internet connections (such as VPN) to minimize costs and reduce latency.

Advantages, disadvantages, and alternatives to private WANs

An obvious advantage of a private WAN is the immediate connection created between multiple network locations, regardless of geographic location. Additionally, WANs have distinct benefits when it comes to security and data recovery; by consolidating an organization s LANs under one umbrella WAN, data is continuously synchronized, has a central backup, and can be transmitted internally without risking potential security breaches that come with Internet transmissions.

Simultaneously, private WANs can be expensive to set up, especially compared to corporate intranets. Maintaining private WANs can also be costly and time consuming, especially when it comes to bandwidth management and service downtimes.

As an alternative to traditional WANs, software-defined WANs (SD-WANs) were introduced to respond to the demand for virtualization. SD-WANs have gained popularity because of their cost-efficiency, reliability, and adaptability. Because SD-WANs are removed from the hardware limitations of traditional WANs, they are also able to scale more easily with a growing business. SD-WAN providers include:

  • VeloCloud
  • Citrix
  • FortiGate
  • CenturyLink
  • Oracle

Vangie Beal
Vangie Beal is a freelance business and technology writer covering Internet technologies and online business since the late '90s.

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