ities. Obviously if there were only two sites, there would only be one link between the two. Traffic requirements would drive the selection, but it's quite likely the links would be bidirectional, and of equal capacity, also called full-duplex, asymmetrical band- width. The arrangement shown is called a "round-robin" because it con- nects all the sites in a series arrangement, with only one link between any two. This arrangement has operational advantages in terms of reliability and robustness; however, it may have disadvantages be- cause the traffic may be more than it can handle in some places and more than needed in others. For now, keep in mind that there are three types of traffic: voice, data, and program content. 5 NETWORK ARCHITECTURE, FACILITIES, AND SERVICES While not explicitly mentioned, the Internet is becoming much more important in many ways; however, it will be included as a potential resource when the traffic is segmented into content creation, distribution, and delivery. Also, don't forget that the Inter- net is nothing more than just another resource built on a set of technology. The technology is the family of Internet proto- cols (IP) that can be used separate and apart from the public Internet to build a private network based on IP standards and tech- niques. Regardless of the basic technologies and all the architectural con- siderations, it is the end-to-end service between any two sites that we seek. Figure 5-3 is simply a reminder of our reference model. Any seemingly complex, multisite network can be decomposed or decoupled into single, defined point-to-point paths, which can be observed, monitored, and measured in many ways. Once end-to-end measurements are made and a profile of its characteristics recorded, it becomes a benchmark for future operations. One last point is that the single path can be broken apart and indi- vidual component performance measured and characterized. One simple obvious characterization is connecting two sets of equipment with wire or fiber, sometimes referred 