red. Deployment of wireless media is faster and less costly than Chapter 2 Traditional Transmission Media deployment of cable, particularly where there is little or no existing infra- structure (e.g., Africa, Asia-Pacific, Latin America, eastern and central Europe). Wireless is also useful where environmental circumstances make it impossible or cost-prohibitive to use cable (e.g., in the Amazon, in the Empty Quarter in Saudi Arabia, on oil rigs). There are a few disadvantages associated with wireless, however. Histori- cally, wireless solutions support much lower data rates than do wired solu- tions, although with new developments in wireless broadband, that is becoming less of an issue (see Part IV, "Wireless Communications"). Wire- less is also greatly affected by external impairments, such as the impact of adverse weather, SO reliability can be difficult to guarantee. However, new developments in laser-based communications-such as virtual fiber-can improve this situation. (Virtual fiber is discussed in Chapter 15, "WMANs, WLANs, and WPANs.") Of course, one of the biggest concerns with wire- less is security: Data must be secured in order to ensure privacy. Fiber optics-Fiber offers enormous bandwidth, immunity to many types of interference and noise, and improved security. Therefore, fiber provides very clear communications and a relatively noise-free environment. The downside of fiber is that it is costly to purchase and deploy because it requires specialized equipment and techniques. Prevailing Conditions and Network Diversity No one of the three categories of media types can be considered best. Each is useful in different situations, and most networks need to take advantage of a number of media types. When building a new network or upgrading an old one, the choice of media type should be based on the prevailing conditions. The saying "Don't put all your eggs in one basket" can be applied to networking. Having multiple pathways of fibers in and out of a building is not always enough. Diver- sity-terrestrial 