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What Is a Wide Area Network (WAN)?

What is WAN and how does it work?

wide area network covers a large geographic area such as a city, state, or country. Connecting parts of a company can be private or public for connecting smaller networks.

Dong Wenjie / Getty Images

How does WAN work?

The easiest way to understand a WAN is to think of the internet, the world’s largest WAN. The Internet is a WAN because it connects many small local area networks or metro networks using ISPs.

On a smaller scale, a company may have a WAN made up of cloud services, its headquarters, and branches. The WAN, in this case, connects these parts of the business.

Regardless of how interconnected the WAN is or the distance between networks, the result is that smaller networks from separate locations can communicate.

The abbreviation WAN is sometimes erroneously used to describe a wireless area network, but is more often abbreviated as WLAN.

How are WANs Connected?

Because WANs by definition cover a longer distance than LANs, it makes sense to connect various parts of the WAN using a virtual private network. This framework secures inter-site communication.

While VPNs provide reasonable levels of security for business use, a public internet connection does not always provide the predictable performance levels that a private WAN connection does. For this reason, fiber optic cables are sometimes used to facilitate communication between WAN links.

X.25, Frame Relay and MPLS

Since the 1970s, many WANs have been built using a technology standard called X.25. These networks supported ATMs, credit card processing systems, and some early online information services such as CompuServe. Older X.25 networks used a 56 Kbps dial-up modem connection.

Frame Relay technology simplifies X.25 protocols and provides a less expensive solution for wide area networks that need to run at higher speeds. Frame Relay became a popular choice for telecommunications companies in the United States during the 1990s, particularly AT&T.

Multiprotocol Label Switching replaced Frame Relay by improving protocol support to handle voice and video traffic in addition to normal data traffic. The MPLS Quality of Service feature was critical to its success. Triple play network services built on MPLS gained popularity in the 2000s and eventually replaced Frame Relay.

Leased lines and Metro Ethernet

Many companies began using leased line WANs in the mid-1990s, when the web and the Internet were booming in popularity. T1 and T3 lines generally support MPLS or Internet VPN communication.

Long-distance point-to-point Ethernet connections can also be used to create private wide area networks. While more expensive than Internet VPNs or MPLS solutions, dedicated Ethernet WANs offer high performance with connections typically rated at 1 Gbps compared to 1.544 Mbps for T1.

A WAN is considered a hybrid WAN if it combines two or more connection types, for example using MPLS circuits and T3 lines. These configurations are a cost-effective way to network branch offices and have a faster way of transferring important data when needed.

Problems with wide area networks

WANs are more expensive than home or corporate intranets.

WANs that cross international and other regional borders fall under different legal jurisdictions. Disputes may arise between governments over property rights and restrictions on network use.

Global WANs require the use of submarine network cables for intercontinental communication. Submarine cables are subject to sabotage and unintentional ruptures from ships and weather conditions. Compared to underground land lines, submarine cables take longer and cost more to repair.


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What Is a Wide Area Network (WAN)?

What is a WAN and how does it work?

A wide area network spans a large geographic area such as a city, state, or country. It can be private to connect parts of a business, or it can be public to connect smaller networks.

Dong Wenjie / Getty Images How a WAN Works

The easiest way to understand a WAN is to think of the internet, the world’s largest WAN. The internet is a WAN because, using ISPs, it connects many smaller local area networks or metro area networks.

On a smaller scale, a business may have a WAN comprised of cloud services, its headquarters, and branch offices. The WAN, in this case, connects those sections of the business.

No matter what the WAN joins together or how far apart the networks are, the result allows smaller networks from separate locations to communicate.

The acronym WAN is sometimes erroneously used to describe a wireless area network, though it’s most often abbreviated as WLAN.
How WANs Are Connected

Since WANs, by definition, cover a larger distance than LANs, it makes sense to connect the various parts of the WAN using a virtual private network. This framework protects communications between sites.

Although VPNs provide reasonable levels of security for business uses, a public internet connection does not always provide the predictable levels of performance that a dedicated WAN link provides. Therefore, fiber optic cables are sometimes used to facilitate communication between the WAN links.

X.25, Frame Relay, and MPLS

Since the 1970s, many WANs were built using a technology standard called X.25. These networks supported automated teller machines, credit card transaction systems, and some early online information services such as CompuServe. Older X.25 networks used 56 Kbps dial-up modem connections.

Frame Relay technology simplifies X.25 protocols and provides a less expensive solution for wide area networks that needed to run at higher speeds. Frame Relay became a popular choice for telecommunications companies in the United States during the 1990s, notably AT&T.

Multiprotocol Label Switching replaced Frame Relay by improving protocol support for handling voice and video traffic in addition to normal data traffic. The Quality of Service feature of MPLS was key to its success. Triple-play network services built on MPLS increased in popularity during the 2000s and eventually replaced Frame Relay.

Leased Lines and Metro Ethernet

Many businesses started using leased line WANs in the mid-1990s as the web and internet exploded in popularity. T1 and T3 lines often support MPLS or internet VPN communications.

Long-distance, point-to-point Ethernet links can also be used to build dedicated wide area networks. While more expensive than internet VPNs or MPLS solutions, private Ethernet WANs offer high performance, with links typically rated at 1 Gbps compared to the 1.544 Mbps of a T1.

If a WAN combines two or more connection types—for example, if it uses MPLS circuits and T3 lines—it is considered a hybrid WAN. These configurations are a cost-effective method to connect network branches and have a faster method of transferring important data if needed.

Problems With Wide Area Networks

WANs are more expensive than home or corporate intranets.

WANs that cross international and other territorial boundaries fall under different legal jurisdictions. Disputes can arise between governments over ownership rights and network usage restrictions.

Global WANs require the use of undersea network cables to communicate across continents. Undersea cables are subject to sabotage and unintentional breaks from ships and weather conditions. Compared to underground landlines, undersea cables tend to take longer and cost more to repair.

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