N2 OLT XGS-PON ONU Splitter GPON OLT NGPON2 ONUs with "tunable" optics tune the receiver to detect the correct wavelengths. XGS-PON NGPONZ Downstream Downstream XGS-PON NGPON2 Upstream GPON Upstream Downstream Upstream FIGURE 11.5 Fiber wavelength band plan with CE. Building the Network of the Future Business broadband services with service-level agreement assurances for a wide variety of speed classes with network on demand (NoD) allowing customers to quickly increase or decrease bandwidth as needed Access transport infrastructure for mobility and cloud support This architecture significantly reduces the complexity of incorporating current and future evolv- ing access technologies, simplifies the development of new services, and reduces the ongoing operat- ing cost of the network. It eliminates the need for totally new hardware and software for each access technology, and it allows new services to be developed once rather than having to be developed sepa- rately for each access technology. With the XGS-PON architecture in place, network operations are in position to implement NGPON2 and any other new innovative access solutions in the future, and to share these access technologies across business and consumer customers and services. 11.4.2 G.FAST TECHNOLOGY In some cases, such as inside existing buildings, the installation of a new fiber optic infrastructure can be cost prohibitive and could delay the availability of next-generation broadband services. In these cases, the best way to distribute new high-speed broadband services is to use short-reach copper-based technologies that can support increased access speeds on existing indoor copper access infrastructure. G.fast is an important technology that can distribute high-speed broadband services over existing coaxial cable or twisted pair wiring within a building or MDU complex. G.fast is the next-generation digital subscriber line (DSL) technology, with performance targets between 150 Mbps and 1 Gbps depending on loop length. G.fast can provide nearly 1 Gbps ag