s that would be affected by any distortions in the network. Video Traffic Video communications, which are becoming increasingly popular and are requiring ever-greater bandwidth, are extremely sensitive to delay. The future is about visual communications. We need to figure out how to make video available over a network infrastructure that can support it and at a price that consumers are willing to pay. When our infrastructures are capable of supporting the capacities and the delay lim- itations required by real-time applications, video will grow by leaps and bounds. An example of a valuable video application comes from the United Kingdom: If a subscriber to Vodaphone in the United Kingdom hears a song she likes at a dance club, she can hold up her phone in the air for a few seconds, and the phone will then receive an SMS providing the name of the song and artist, along with a "click- here" link to buy the CD, charge it to her phone bill, and ship it to her address on file. Not only is this a major convenience for the customer, it is also a substantial revenue generator for the service provider. Increasing Backbone and Access Bandwidth All the new voice, data, and video traffic means that backbone traffic levels are growing as well. Many of the changes discussed SO far-primarily the changes in traffic patterns and applications-will require immense amounts of backbone bandwidth. In addition, xxxviii Introduction advances in broadband access technologies will drive demand for additional capacity in network backbones. When 100Gbps broadband residential access becomes available (and there are developments on the horizon), the core networks will require capacities measured in exabits per second (i.e., 1 billion billion bps). These backbone bandwidth demands make the revolutionary forces of optical networking and wireless broadband critical to our future. (Optical networking is discussed in detail in Chapter 11, "Optical Networking.") Handling New Types of Applications The new traffic patterns imply that the next-generat