urse, you need to consider security requirements. Again, there is no such thing as complete security, and each situation needs a different amount of secu- rity. You need to add encryption and other security mechanisms in almost any envi- ronment, but in some cases, you need to take the extra step of choosing a medium that's more difficult to tap into, such as coax or fiber. Mind you, both can be breached; it's a matter of how easy it is to do SO (based on physical access) and how quickly unauthorized taps can be detected (with the help of testing equipment). Most of the LAN standards today support the full range of media types. They vary in terms of factors such as the distances allowed between the devices and their backbones, SO you need to choose the media appropriate to your situation. LAN Transport Techniques and Standards An important feature of a LAN is its transport technique: whether it is broadband or baseband (see Figure 6.2). Broadband means multichannel, so a broadband LAN implies that, through Frequency Division Multiplexing (FDM), multiple Channel 1 Channel 2 Frequency Frequency Spectrum Spectrum Broadband Baseband Figure 6.2 Broadband versus baseband Chapter 6 Local Area Networking independent channels can carry analog or digital information, depending on the interfaces. This is essentially the way traditional cable TV operates: There are mul- tiple channels of programming, and each one runs over a different portion of the frequency band. When you request a particular channel from the interface device (the set-top box), the device selects the frequency band on which that channel is allocated. Cable TV is a multichannel coaxial system. Baseband implies a single-channel digital system, and this single channel car- ries information in containers-that is, packets or frames-that are specified by the LAN standard in use. The traditional LAN standards are Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI). Table 6.1 compares these three standards. The vast majority of LANs-probably 85% or m