Passive optical network
In this use, a PON has a point-to-multipoint topology in which an ISP uses a single device to serve many end-user sites using a system such as 10G-PON or GPON.[5] A PON reduces the amount of fiber and central office equipment required compared with point-to-point architectures with dedicated connections for every user.The Society of Cable Telecommunications Engineers (SCTE) also specified radio frequency over glass for carrying signals over a passive optical network.Further improvements to the original APON standard – as well as the gradual falling out of favor of ATM as a protocol – led to the full, final version of ITU-T G.983 being referred to more often as broadband PON, or BPON.A typical APON/BPON provides 622 megabits per second (Mbit/s) (OC-12) of downstream bandwidth and 155 Mbit/s (OC-3) of upstream traffic, although the standard accommodates higher rates.GPON Encapsulation Method (GEM) allows very efficient packaging of user traffic with frame segmentation.The chief information officer of the United States Department of the Army issued a directive to adopt the technology by fiscal year 2013.[28][29][30][31] GPON used in Fiber to the x deployments may face vulnerability to Denial-of-service attack via optical signal injections, unresolved based on current commercially available technologies.EPON is a "short haul" network using Ethernet packets, fiber optic cables, and single protocol layer.10G EPON is fully compatible with other Ethernet standards and requires no conversion or encapsulation to connect to Ethernet-based networks on either the upstream or downstream end.This technology connects seamlessly with any type of IP-based or packetized communications, and, thanks to the ubiquity of Ethernet installations in homes, workplaces, and elsewhere, EPON is generally very inexpensive to implement.[42] Splitters can be made with either planar lightwave circuit (PLC) or fused biconical taper (FBT) technologies: PLC creates optical waveguides in a flat substrate made of silica to split light, and FBT fuses optical fibers together to create a splitter.In multiple-tenant units, the ONU may be bridged to a customer premises device within the individual dwelling unit using technologies such as Ethernet over twisted pair, G.hn (a high-speed ITU-T standard that can operate over any existing home wiring - power lines, phone lines and coaxial cables) or DSL.Some ONUs implement a separate subscriber unit to provide services such as telephony, Ethernet data, or video.These typically include: The ONT or ONU terminates the PON and presents the native service interfaces to the user.Often the ONU functions are separated into two parts: A PON is a shared network, in that the OLT sends a single stream of downstream traffic that is seen by all ONUs.Because the optical distribution network (ODN) is shared, ONU upstream transmissions could collide if they were transmitted at random times.NSR DBA has the advantage that it imposes no requirements on the ONU, and the disadvantage that there is no way for the OLT to know how best to assign bandwidth across several ONUs that need more.[49] Data Over Cable Service Interface Specification (DOCSIS) Provisioning of Ethernet Passive Optical Network, or DPoE, is a set of CableLabs specifications that implement the DOCSIS service layer interface on existing Ethernet PON (EPON, GEPON or 10G-EPON) media access control (MAC) and physical layer (PHY) standards.In short it implements the DOCSIS Operations Administration Maintenance and Provisioning (OAMP) functionality on existing EPON equipment.Comcast Xfinity[50] and Charter Spectrum[51] use 10G-EPON with DPoE in newly deployed areas, including new construction and rural expansion.The overlay for RFoG is based on wavelength-division multiplexing (WDM)—the passive combination of wavelengths on a single strand of glass.The multiple wavelengths of a WDM-PON can be used to separate Optical Network Units (ONUs) into several virtual PONs co-existing on the same physical infrastructure.Advantages: The MAC layer is simplified because the P2P connections between OLT and ONUs are realized in wavelength domain, so no P2MP media access control is needed.Work by Davey and Payne at BT showed that significant cost savings could be made by reducing the electronic equipment and real-estate required at the local exchange or wire center.A beam splitter cannot provide any switching or buffering capabilities and does not use any power supply; the resulting connection is called a point-to-multipoint link.In addition, since splitters have no buffering, each individual optical network terminal must be coordinated in a multiplexing scheme to prevent signals sent by customers from colliding with each other.Single-mode, passive optical components include branching devices such as Wavelength-Division Multiplexer/Demultiplexers (WDMs), isolators, circulators, and filters.A given component may combine and divide optical signals simultaneously, as in bidirectional (duplex) transmission over a single fiber.Isolators are used as both integral and in-line components in laser diode modules and optical amplifiers, and to reduce noise caused by multi-path reflection in high-bitrate and analog transmission systems.
SC APCoptical network terminalsfiber-opticlast mileInternet service providers10G-PONsplitteroptical line terminaloptical network unitspoint-to-pointaccess networkdownstreamEncryptioneavesdroppingUpstreammultiple accesstime-division multiple accessBritish TelecommunicationsInstitute of Electrical and Electronics EngineersTelecommunication Standardization SectorInternational Telecommunication UnionSociety of Cable Telecommunications Engineersradio frequency over glassCableLabsfiber to the homeAsynchronous Transfer ModeVerizonBritish TelecomSaudi Telecom CompanyEtisalatSIPRNetU.S. Air Forceprotective distribution systemNSTISSI 7003US federal governmentchief information officerUnited States Department of the ArmyTelos CorporationFiber to the xDenial-of-service attack10G-EPONEthernetEthernet in the first mileIEEE 802.310 Gbit/s EPONwavelength planwavelength-division multiplexingoptical power budgetsForward error correctionpower linescoaxial cablescore networkFast EthernetGigabit Ethernet10 Gigabit EthernetSDH/SONETplain old telephone servicetelemetrycoaxial cabledynamic bandwidth allocationtraffic engineeringstatistical multiplexingservice level agreementXGS-PONDOCSISmedia access controlphysical layerCable Modem Termination SystemsComcastXfinityCharterSpectrumhybrid fiber-coaxialFrontier CommunicationsZiply FiberNG-PON2XG-PONburst mode clock and data recoverycontinuous modebeam splittersbroadcastmultiplexingtime-division multiplexinganaloganalog televisionoutside plantoptical distribution frameFiber In The LoopHybrid Fiber-Coaxial CableSynchronous Optical NetworkSynchronous Digital HierarchyTelcordia Technologiesoptical isolatoroptical circulatorfiber optic filterHigher Speed PONBandwidth guaranteed pollingBroadbandInterleaved polling with adaptive cycle timeBibcodeWayback MachineTelecommunicationsHistoryBroadcastingCable protection systemCable TVData compressionDigital mediaInternet videoonline video platformsocial mediastreamingEdholm's lawInformation AgeInformation revolutionInternetMobile phoneSmartphoneOptical telecommunicationOptical telegraphyPhotophonePrepaid mobile phoneRadiotelephoneSatellite communicationsSemaphorePhryctoria