Optical splitters creating a point to multipoint topology are also the same technology regardless of the type of PON system, making any PON network upgradable by changing the optical network terminals (ONT) and optical line terminal (OLT) terminals at each end, with minimal change to the physical network. Access networks usually also must support point-to-point technologies such as Ethernet, which bypasses any outside plant splitter to achieve a dedicated link to the telephone exchange. Some PON networks use a "home run" topology where roadside cabinets only contain patch panels so that all splitters are located centrally. While a 20% higher capital cost could be expected, home run networks may encourage a more competitive wholesale market since providers' equipment can achieve higher use. See also Edge device Hierarchical internetworking model Internet access IP connectivity access network Local loop Passive Optical Network References External links Interactive presentation introducing the technology and design of access networks Telecommunications infrastructure Network access Fiber to the premises