LANs, WANs, and MANs
Networks are categorized according to how many locations they span. A network that is confined to a single location is known as a LAN. Networks that span multiple geographic locations are known as WANs. There is also another category, called a MAN, which is used to classify networks that fall somewhere between LANs and WANs. The following sections examine the characteristics of these types of networks.
LANs
A LAN is confined to a single geographic location, such as a single building, office, or school. LANs are created with networking media that are very fast but that can cover a limited distance. Figure 1.4 shows an example of a LAN.
EXAM TIP
LAN/WAN Technologies An understanding of the technologies used in both LANs and WANs is required for the Network+ test. These technologies are covered in detail throughout the rest of this book.
WANs
A WAN is a network that spans multiple geographic locations. WANs are generally slower than LANs and are considerably more expensive to run. WANs are all about bandwidth, and the more bandwidth you are willing to pay for, the more speed you can get. WANs connect LANs together to create an internetwork. Figure 1.5 shows an example of a WAN.
Figure 1.5. An example of a WAN.
WANs often use different technologies from LANs. WAN technologies are discussed in Chapter 7, “WAN Technologies.”
NOTE
When Does a LAN Become a WAN? Technically, a LAN never becomes a WAN. If the definitions of LAN and WAN were taken literally and applied to a working model that had three connected sites, the portions of the network confined within each site would be LANs and the network elements connecting the sites together would be called the WAN. You should avoid the temptation to refer to the entire internetwork as a WAN because WANs and LANs employ some very different technologies.
MANs
A MAN is confined to a certain geographic area such as a university campus or a city. No formal guidelines dictate the differences between a MAN and a WAN; technically, a MAN is a WAN. Perhaps for this reason, the term MAN is used less frequently than WAN. If any distinction exists, it's that a MAN is smaller than a WAN.
NOTE
CANs You might hear the term campus area network (CAN) in discussions of network layouts. A CAN is a network that spans a defined single location (such as an office complex with multiple buildings or a college campus) but is not large enough to be considered a WAN.
Having established the purpose and function of networks and how networks are classified based on size, the following section looks at the specific features of a network, beginning with LAN topologies.