 nor is it exhaustive or all-inclusive: Access, switching, and transport elements Access and transport facilities can be terrestrial, satellite, or a com- bination Switch facilities will be time (TDM), cell (ATM), or packet (IP) Service availability is full-time 24/7 or shared Availability, reliability, robustness, grade, and quality of service Capital and operating cost Geographical or physical coverage includes local (LAN), metropol- itan (MAN), regional, national, and global turf (WAN) LANs may have single or multiple segments covering a room, floor, building or group of buildings in a campus arrangement A MAN typically involves third party telco or ISP service and uses standard telephone facilities, such as E1/T1, E3/DS3 WAN extends LAN and MAN to wider geographic areas not covered by local telephone companies and ISPs Content transport networks can be built or bought, but practical realization is a combination of buying equipment and the rights to use facilities and services. PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS TABLE 3-1 Content Transport technology or methodology ATM CBR ATM VBR Frame Relay Ethernet Voice (Real Time) Maybe Video (Real Time) Maybe HTML Or Similar Table 3-1 summarizes the types of network transport technology or methodology and it's usefulness for transporting various types of content. Verbal descriptions of network elements-the terms used to deal with network elements-are a common source of confusion. Symbols used throughout the industry are equal sources of confusion. Who knows why it's that way; maybe this is nothing more than a set of behavior consistent with the many meanings and uses of the word network. Adequately defining and describing a network is at best a challenge. Consider for example the famous, or infamous, cloud. The metaphor has more than a little in common with the white things in the sky. Clouds represent the weather. The weather is always changing, somewhat unpredictable, and never controllable. Networks are the same, except maybe a bit more 