It is universally known that fiber optics transmit data by light signals. And as this data moves across a fiber, there needs a way to separate it so that it gets to the proper destination. Generally, there exist two essential types of systems that make fiber-to-the-home broadband connections possible, which are active optical networks (AON) and passive optical networks (PON). Both of them provide ways to separate data and route it to the proper place. Nowadays, service providers invest billions of dollars in their access networks to meet the ever increasing demand for high-bandwidth broadband. In addition to technology longevity, service providers also like to see technology evolution to ensure future consumer demands can be met by staying within the same technology family. Consequently, the development of passive optical networking is on the rise.
The Definition of PON
A passive optical network (PON) is a system that brings optical fiber cabling and signals all or most of the way to the end user. It is a telecommunication technology that implements a point-to-multipoint architecture, in which unpowered fiber optic splitters are used to enable a single optical fiber to serve multiple end-points such as customers, without having to provision individual fibers between the hub and customer. The system can be described as fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB), or fiber-to-the-home (FTTH).
A PON consists of an optical line termination (OLT) at the service provider’s central office and a number of optical network units (ONUs) near end users. Typically, up to 32 ONUs can be connected to an OLT. The passive optical network simply describes the fact that optical transmission has no power requirements or active electronic parts once the signal is going through the network.
A PON system makes it possible to share expensive components for FTTH. A passive splitter that takes one input and splits it to broadcast to many users, which help cut the cost of the links substantially by sharing, for example, one expensive laser with up to 32 homes. PON splitters are bi-directional, that is signals can be sent downstream from the central office, broadcast to all users, and signals from the users can be sent upstream and combined into one fiber to communicate with the central office.
Difference Between AON and PON
As it was mentioned above, AON and PON serve as the two main methods of building CWDM and DWDM backbone network. Each of them has their own merits and demerits.
An active optical system uses electrically powered switching equipment, such as a router or a switch aggregator, to manage signal distribution and direction signals to specific customers. This switch directs the incoming and outgoing signals to the proper place by opening and closing in various ways. In such a system, a customer may have a dedicated fiber running to his or her house. The reliance of AON on Ethernet technology makes interoperability among vendors easy. Subscribers can select hardware that delivers an appropriate data transmission rate and scale up as their needs increase without having to restructure the network. However, AON require at least one switch aggregator for every 48 subscribes. Since it requires power, an active optical network inherently is less reliable than a passive optical network.
A passive optical network, on the other hand, does not include electrically powered switching equipment, instead, it uses optical splitters to separate and collect optical signals as they move through the network. A PON shares fiber optic strands for portions of the network. Powered equipment is required only at the source and receiving ends of the signal. PONs are efficient since each fiber optic strand can serve up to 32 users. Besides, PONs have a low building cost compared with active optical networks along with lower maintenance cost. However, PONs also have some demerits. They have less range than an AON, which means subscribes must be geographically closer to the central source of the data. When a failure occurs, it is rather difficult to isolate it in a PONs. Moreover, because the bandwidth in a PON is not dedicated to individual subscribers, data transmission speed may slow down during peak usage times in an effect known as latency. And latency would quickly degrade services such as audio and video, which need a smooth rate to maintain quality.
The Benefits of PON
As early as the year 2009, 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 are listed 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
- Fiber is more secured than copper. It is harder to tap. There is no available sniffer port on a passive optical splitter. Data is encrypted between the OLT and the ONT.
Conclusion
From what we have discussed above, you may at least have a brief understanding of the passive optical network. In fact, PON has been around for many years in the service provider space. Now PON is finally making its way into the enterprise space by providing opportunities for customers deploying new infrastructure or new construction. The technology is catching on. Now, PON mainly captures the commercial market, which performs well in healthcare, college campuses, hotels and office buildings. A PON network eliminates the need for switches and a wiring closet, which means fewer points of failure.
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