Local Area Network (LAN) Types
A WAN is a type of Local Area Network (LAN). A LAN is a private network that typically is made up of a well-connected, reliable, and fast network connection. Alternatives on the LAN framework include CANs, MANs, and WANs. All three of these network options are illustrated below:
If you take the LAN network model and make it slightly larger, you end up with several buildings in a single area that are interconnected. This kind of network is referred to as a campus environment or a Campus Area Network (CAN). In this case, the interconnections between the buildings may be provided by internal resources or by a telephone company or service provider.
In most cases, the interconnection of these buildings is a private investment in a network infrastructure because these links will be used indefinitely.
If you use external network providers, you can still refer to this infrastructure as a WAN. However, because the network is typically a private network structure, many organizations refer to it as a LAN.
This LAN may be a flat network with switches connecting all of these buildings on a campus or the floors of a building, but because you want to reduce broadcasts spanning your entire network and passing though remote buildings, you probably will implement a series of routers. These routers perform better than switches when managing network traffic and conserving bandwidth for other applications.
If your buildings are more dispersed, say around a city, your network increases to a Metropolitan Area Network (MAN). In this case, the odds are very high that you will not own the entire network infrastructure, so you will be buying or leasing network connectivity from a service provider.
Because your network connections are fairly short range and may all be hosted by one provider, the technology choices may allow you to utilize higher speed or cheaper technologies over traditional WAN technologies. These choices are entirely dependent on what your service provider can offer.
Finally, you get into Wide Area Network (WAN), using traditional WAN connectivity options such as Frame Relay and switched circuits. These technologies allow you to create a multi-location LAN, or WAN, that could span the globe.
In that case, you are dealing with and negotiating connections in many countries and getting all of your service providers or telephone companies to communicate with each other, so you probably need to rely on a routing protocol to deal with the changing link states and network availability.