Tag: OLT

Introduction to Passive Optical Network (PON)

Seen from the entire network structures，the Passive Optical Network (PON) market is in a high-growth period due to the ongoing deployments of Fiber to the Home (FTTH) networks

Seen from the entire network structures，the Passive Optical Network (PON) market is in a high-growth period due to the ongoing deployments of Fiber to the Home (FTTH) networks.today, we mainly Introduce Passive Optical Network (PON).

What does Passive Optical Network (PON)mean?

A passive optical network (PON) is a cabling system that uses optical fibers and optical splitters to deliver services to multiple access points. A PON system can be fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB) or fiber-to-the-home (FTTH). A PON system consists of optical line termination (OLT) at the communication provider’s end and a number of optical network units (ONUs) at the user’s end. The term “passive” simply means that there are no power requirements while the network is up and running.

 

A PON consists of an optical line terminal (OLT) at the service provider’s central office (hub) and a number of optical network units (ONUs) or optical network terminals (ONTs), near end users. A PON reduces the amount of fiber and central office equipment required compared with point-to-point architectures. A passive optical network is a form of fiber-optic access network.In most cases, downstream signals are broadcast to all premises sharing multiple fibers. Encryption can prevent eavesdropping.upstream signals are combined using a multiple access protocol, usually time division multiple access (TDMA).

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Feature

A PON takes advantage of wavelength division multiplexing (WDM), using one wavelength for downstream traffic and another for upstream traffic on a single mode fiber (ITU-T G.652). BPON, EPON, GEPON, and GPON have the same basic wavelength plan and use the 1490 nanometer (nm) wavelength for downstream traffic and 1310 nm wavelength for upstream traffic. most common is 28 dB of loss budget for both BPON and GPON, but products have been announced using less expensive optics as well. 28 dB corresponds to about 20 km with a 32-way split. Forward error correction (FEC) may provide for another 2–3 dB of loss budget on GPON systems. As optics improve, the 28 dB budget will likely increase. Although both the GPON and EPON protocols permit large split ratios (up to 128 subscribers for GPON, up to 32,768 for EPON), in practice most PONs are deployed with a split ratio of 1:32 or smaller.

A PON consists of a central office node, called an optical line terminal (OLT), one or more user nodes, called optical network units (ONUs) or optical network terminals (ONTs), and the fibers and splitters between them, called the optical distribution network (ODN). “ONT” is an ITU-T term to describe a single-tenant ONU. 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. An ONU is a device that terminates the PON and presents customer service interfaces to the user. Some ONUs implement a separate subscriber unit to provide services such as telephony, Ethernet data, or video.

An OLT provides the interface between a PON and a service provider′s core network. These typically include:

  • IP traffic over Fast Ethernet, gigabit Ethernet, or 10 Gigabit Ethernet;
  • Standard TDM interfaces such as SDH/SONET;
  • ATM UNI at 155–622 Mbit/s.

functions are separated into two parts:

  • The ONU, which terminates the PON and presents a converged interface—such as DSL, coaxial cable, or multiservice Ethernet—toward the user;
  • Network termination equipment (NTE), which inputs the converged interface and outputs native service interfaces to the user, such as Ethernet and POTS.

 

The Benefits of PON

As early as before, PONs began appearing in corporate networks. Users were adopting these networks because they were cheaper, faster, lower in power consumption, easier to provision for voice, data and video, and easier to manage, since they were originally designed to connect millions of homes for telephone, Internet and TV services.Passive Optical Networks (PON) provide high-speed, high-bandwidth and secure voice, video and data service delivery over a combined fiber network.

The main benefits of PON as below:

  • Lower network operational costs
  • Elimination of Ethernet switches in the network
  • Elimination of recurring costs associated with a fabric of Ethernet switches in the network
  • Lower installation (CapEx) costs for a new or upgraded network (min 200 users)
  • Lower network energy (OpEx) costs
  • Less network infrastructure
  • You can reclaim wiring closet (IDF) real estate
  • Large bundles of copper cable are replaced with small single mode optical fiber cable
  • PON provides increased distance between data center and desktop (>20 kilometers)
  • Network maintenance is easier and less expensive

 

Conclusion

According to the above article, you may have a understanding of the passive optical network.A PON network eliminates the need for switches and a wiring closet, which means fewer points of failure. Fiber-Mart manufactures and offers customized services. any question pls welcome to visit www.fiber-mart.com or contact us.E-mail: service@fiber-mart.com

What are the differences among OLT, ONU and ONT?

In recent years, Fiber to the Home (FTTH) is rapidly developing support technologies. The TOLT, ONU and ONT are now widely used in fiber network access in city. 

In recent years, Fiber to the Home (FTTH) is rapidly developing support technologies. The TOLT, ONU and ONT are now widely used in fiber network access in city. It can help efficiently reduce network construction cost, while simultaneously providing a guarantee on high bandwidth and high integration.

 

Optical Line Terminal (OLT)

 

OLT (Optical Line Terminal) is the endpoint hardware device located at the central office in a Passive Optical Network (PON). The OLT contains a central processing unit, a gateway router, voice gateway uplink cards and passive optical network cards. The main functionality of the OLT is to adapt the incoming traffic (voice/data/video) from the metropolitan rings into the PON transport layer. It can transmit a data signal to users at 1490nm wavelength. That signal can serve up to 128 ONTs at a range of up to 12.5 miles by using Optical Splitters.

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Optical Network Unit (ONU)

 

ONU converts optical signals transmitted via fiber to electrical signals. These electrical signals are then sent to individual subscribers. In general, there is a distance or other access network between ONU and end user’s premises. Furthermore, ONU can send, aggregate and groom different types of data coming from customer and send it upstream to the OLT. Grooming is the process that optimises and reorganises the data stream so it would be delivered more efficient. OLT supports bandwidth allocation that allows to make smooth delivery of data float to the OLT, that usually arrives in bursts from customer. ONU could be connected by various methods and cable types, like twisted-pair copper wire, coaxial cable, optical fiber or Wi-Fi.

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Optical Network Terminal (ONT)

 

ONU and ONT are basically the same device – ONT is located at the customer premise, and ONU is located outside the home. ONU can be working in different temperature and weather conditions. It should resist water, winds and vandals. The ONU usually communicates with an optical network terminal (ONT), which may be a separate box that connects the PON to TV sets, telephones, computers, or a wireless router.

 

Functions

OLT is generally employed for terminal connected to the fiber backbone. An OLT has two primary functions:

  • Converting the standard signals use by a FiOS service provider to the frequency and framing used by the PON system;
  • Coordinating the multiplexing between the conversion devices on the optical network terminals (OLTs) located on the customers’ premises.

 

ONT (Optical Network Terminal), also ONU (Optical Network Unit)

ONT location,is at the customer’s premises. Its purpose is to use optical fiber for connecting to the PON on the one side, while interfacing with customers on the other side. ONT supports wide variety of interfaces, depending on requirements of customer:

  • Digital video formats
  • Analog video formats
  • ATM interfaces (155 Mbps)
  • DS3 or E3 telephone connections (44.736 or 34.368 Mbps)
  • T1 or E1 (1.544 or 2.048 Mbps)
  • Various Ethernet rates

 

To describe simply, OLT means Optical Line Terminal. ONU is the Optical Network Unit. ONT means Optical Network Terminal.OLT use fiber cables, adapters and others to connect with ONU and ONT, in order to build ODN (Optical Distribution Network).Both of ONU and ONT are client-side devices, no difference in nature, but if you have to distinguish, it can be seen from the name difference.ONT is the optical network terminal, applied to the end user, and ONU refers to the optical network unit, which is with the end user. There may be other networks.give a simple example, such as in a district, ONT is directly on the user’s home equipment, and ONU may be placed in the corridor, each user through the switch and other equipment connected to the ONU.

 

Conclusion

The development of fiber optic networks, ONT and OLT are indispensable components in the GPON network system. Fiber-Mart provides OLTs for both EPON and GPON systems. Any question pls feel free to contact with us. E-mail: Service@fiber-mart.com