 standards are listed in Table 4-3 in the "Appendix." PON Components-OLTs and ONTs OLTs (Optical Line Terminals) are switches with ports on each card. They are located in central offices where they are connected to network nodes in the outside network of cable TV and telephone companies. See Figure 4-11 for an example of an OLT. OLTs place optical signals on the correct fiber optic cable. Each OLT card has from four to eight ports and each port is connected to a specific fiber strand. www.TechnicalPDF.com are virtual network functions (VNFs) in a White Box on X86 Intel commodity servers. Representing NG PON2S optical line terminals in software makes them less costly to install than separate pieces of hardware. Optical Network Terminals (ONTs) translate between signals on fiber cabling and those on copper cabling as well as between optical signals and wireless signals. ONTs are located wherever fiber optic cabling is connected to other types of cabling and wireless medium where signals need to be translated. This makes them compatible with all types of media. The following are examples of locations with ONTs: Homes Enterprises distribution frames where copper cabling is terminated Apartment buildings Wi-Fi modems if all signals within a building are transmitted on Wi-Fi Hospitals Cellular backhaul where signals are "backhauled" from cellular data centers to networks Wholesale cellular backhaul providers who resell backhaul capacity to facilities-based cellular companies Coaxial cabling in cable TV networks where fiber is installed in residential neighborhoods closer to homes Nodes in neighborhoods where fiber is terminated closer to, but not directly connected to a residence or small business Direct Fiber to Enterprises and Multi-Tenant Buildings Direct fiber is often installed at enterprises and multi- tenant buildings. Because it is directly connected from the central office, PON equipment is not needed. In apartment buildings, data-grade copper carries signals to each apartment unit from the ONT. The ONT conver