 areas. Handed off to other long-haul carriers to be transmitted on other routes. Transmitted to Metropolitan Area Networks (MANs) located in cities. Sent to residential and business customers over last-mile networks by either the long-haul carrier, the local landline telephone company, or a cellular telephone company. Carriers also transmit data and VoIP traffic between enterprise sites on long-haul networks. Special arrangements are made with these customers for optional services such as security and priority treatment for voice and video conferencing. These networks are considered part of a carrier's private data networks. They are separate from the Internet and offer guaranteed www.TechnicalPDF.com speeds and low latency (unnoticeable levels of delay or no delay) on an end-to-end basis. For more on this, see Chapter 5, "Broadband Network Services." Software Defined Networks to Manage Traffic Surges Telephone companies are increasingly upgrading sections of their networks, often in anticipation of upgrading fully to SDN to manage the annual doubling of traffic on networks. SDN, as the name implies, controls networks via policies created in software to manage traffic. The growing amounts of traffic in carriers' networks is due mainly to data the increasing amounts of traffic to and from the cloud, and from streaming video from Netflix, Amazon, and others. Movies and TV shows that formerly were exclusively available on cable TV networks are now streamed 24 hours a day from sources such as Amazon, Netflix, and Hulu. This causes unpredictable spikes in traffic. Increasingly, cable TV and traditional telephone company customers want anytime-anywhere availability of movies and TV shows. They stream content to smartphones, tablet computers, and Internet-connected televisions at any hour of the day or night. Streaming video needs to be treated differently from e-mail and text messages. Video in the form of movies and conference calls needs to be prioritized SO that delays don't cause breaks and pauses in the audio or 