, it was not widely available, both because it required fiber-optic cabling to the customer and because the central offices of providers were not widely equipped with GigE switches. In contrast, carriers now offer GigE services to small and medium-sized organizations as well as large ones. GigE is now more widely available because more central offices have been equipped to support it and fiber is more widely deployed to business customers. These services start at speeds of 10Mbps and currently scale up to 100Gbps. Capacity is expected to increase to 400Gbps in the future. Facebook and Google are experimenting with 400 Gigabit Ethernet in the WAN. Bandwidth demand by all types of organizations has created the impetus for carriers to invest in gear that meets this demand. Customers that previously used T3 service now have either Megabit or Gigabit Ethernet. Smaller organizations can order the slower Ethernet service of 20, 30, or 60 megabits with the option to easily upgrade later. Moreover, most carriers including Windstream, Verizon, and AT&T have retired all non- Ethernet services including T1 and T3 services. Carrier Gigabit Ethernet Flexibility and Scalable Speeds Gigabit Ethernet is offered by carriers for accessing the Internet, MPLS networks, and connections to other sites within cities. When used for accessing these networks, enterprises might use GigE at their headquarters. At www.TechnicalPDF.com remote sites, depending on the level of traffic at each site, slower data rates might be adequate. See Figure 5-5 for an example of Carrier Gig-E at a multi-site organization. Importantly, once Carrier GigE is installed, enterprise customers can request that their telephone company provider increase or decrease the capacity of their service remotely. This is done by modifying data rates remotely at the central office. Cabling does not have to be changed and most customers' Carrier Ethernet switches can be programmed for added capacity. Because there are few requirements for technicians onsite to make changes, Gi