WAN (Wide Area Network)

WANs are large-scale networks that can stretch over countries and even continents. They don’t connect individual routers but interconnect other networks like LANs or MANs. WANs can be public or operated by companies in order to link different locations over long distances. But how is a WAN set up, how does it differ from other sorts of networks, and which technologies are used?

WAN is the abbreviation for Wide Area Network. These networks cover large geographical regions and link different smaller networks like LANs (Local Area Networks) or MANs (Metropolitan Area Networks) with one another. For this reason, they are only used in a professional context.

Public WANs are operated by internet providers so that their customers can access the internet. Private Wide Area Networks are primarily set up by companies in order to enable cloud services, for example, and connect the networks of different company locations.

Besides WANs, there are similar terms such as WLANs, LANs, and MANs. The technologies behind these networks are related to the Wide Area Network but refer to different structures. LANs and MANs mainly differ from WANs in terms of size.

LAN stands for Local Area Network. It refers to the interconnection of multiple computers at a single location (company premises, households, etc.) into a network, allowing the computers to exchange information or access another network. The data transmission rate of LANs is far quicker compared to WANs, since the distances involved are much smaller.

MAN stands for Metropolitan Area Network. The network is the bigger brother of the LAN and connects cities and metropolitan regions over distances of up to 100 kilometres, but is still smaller than a WAN. MAN uses fibre optic technology in order to link multiple LANs with each other.

By contrast, a Wireless Local Area Network (WLAN) is actually a LAN that works without the use of cable connections. Here, wireless communications technology is used to allow the individual computers to talk to each other or another network like the internet, for example. Like a LAN, a WLAN can therefore be connected to a MAN which may in turn be connected to a Wide Area Network.

Since whole networks rather than individual computers are interconnected with a WAN, the technology used differs in comparison with other network types. Other transmission protocols and address concepts are applied.

WANs use transmission technologies and protocols in up to three layers as part of the OSI reference model. A WAN thereby works on a bit transmission layer (layer 1), the security layer (layer 2), and the network layer (layer 3).

Wide Area Networks use a consistent address scheme, since unaddressed data transmission would be inefficient with the number of connected networks. Intermediate systems or network nodes like switches, bridges, and routers enable the data packets sent to be forwarded to the right address. Using hardware, data packets are sent from a subnetwork to another and then delivered to the correct network participant – which could be a PC, smartphone, TV or even a smart fridge. The underlying technology is TCP/IP protocol stacks. The different protocols of this protocol family ensure that data is addressed correctly and reaches the right destination even in the event of transport difficulties, for example.

The following technologies are also used for data transmission:

• X.25 (older technology, since the 1970s)
• Asynchronous Transfer Mode (ATM) (older technology)
• Multiprotocol Label Switching (IP/MPLS)
• Plesiochronous Digital Hierarchy (PDH)
• Synchronous Digital Hierarchy (SDH)
• Ethernet

Copper and fibre optic cables as well as wireless connections are used as physical transmission media. Fibre optic cable is particularly suitable for connections over great distances of land and water. Innovations include satellite-supported broadband data transmission, which can be set up relatively quickly. In practice, a mixture of different transmission media is typically used. The various types of cables can be connected with each other with the use of media convertors. At major internet nodes – special points of exchange – more than hundreds of networks are often interconnected to enable efficient data exchange. Repeaters ensure that data packets don’t lose any information as they travel across large distances.