ly controlled in order to support real- time voice streams. Losses must also be controlled; while a few lost packets results in pops and clicks, a substantial loss renders a conversation unintelligible. (Con- cepts such as delay, latency, and error control are discussed in Chapter 5, "Data Communications Basics.") Data Traffic The term data communications refers to the exchange of digitized text or document information between two machines (see Chapter 5). Data encompasses many dif- ferent information types. In the past, we saw these different types as separate enti- ties (e.g., video and voice in a videoconference), but in the future, we must be careful not to separate things this way because, after all, in the digital age, all data Adapting to New Traffic Patterns xxxvii is represented as ones and zeros. Perhaps it is best to think of traditional data as involving text and document exchange. Depending on the application supported, the bandwidth or capacity requirements can range from medium to high. As more objects that are visual in nature (such as images and video) are included with the data, that capacity demand increases. Different types of data applications have varying levels of tolerance for delay. Text-based exchanges are generally quite toler- ant of delays. The more real-time nature there is to the information type, as video, the tighter the control you need over the latencies. Data traffic is growing much faster than voice traffic; it has grown at an average rate of about 30% to 40% per year for the past decade. To accommodate data com- munication, network services have been developed to address the need for greater capacity, cleaner transmission facilities, and smarter network management tools. Image Traffic Image communications require medium to high bandwidth: The greater the resolu- tion required, the greater the bandwidth required. For example, many of the images taken in medical diagnostics require very high resolution. Image traffic tol- erates some delay because it includes no motion artifact