Passive Optical LAN (POL) – Changing the Way We Think About Designing the LAN

Posted on by FS.COM

Fiberstore-POL-solutionTo replace the copper-based networks with fiber optics appears to be a trend of nowaday network infrastructure. At the same time, the development of Passive Optical Network (PON) technology definitely offers a more cost-effective and more safe solution of fiber optics cabling. These new technologies naturally change the game in enterprise networks. Fiber-based passive optical LAN (POL), as a particularly promising alternative for enterprises in need of a secure, converged network with increased bandwidth, has emerged to satisfy the demands of many enterprise networks.

What’s Passive Optical LAN (POL)?

POL, short for passive optical local area network, is a Layer-2 transport medium, built with passive optical network (PON) technology, which provides converged data, video, and voice services at Gigabit speeds over a single strand of fiber to the user’s location. POL is more environment-friendly than the traditional copper-based Ethernet LAN and it uses standard FTTh(Fiber to the home) architecture and protocols that are quite different from typical LAN. Compared with the traditional LAN, POL is a more cost-effective and energy efficient alternative as it uses a different architecture with single-mode fiber that makes the user and electronic devices become more closer than the traditional LAN, eliminating distance constraints and reducing the quantity of cable to the workstations. In addition, with its “passive” and “optical” features, it uses less energy and consumes far less space and raw materials compared to copper cabling. Moreover, since the ONTs can support multiple devices, the POL can save the cost of cables and labor. This is why it is also called “green” network.

Composition and Structure of POL

Similarly with PON, there’s no need for active electronics between the main equipment room and the work areas. A typical POL consists of optical line terminal (OLT), optical splitter and optical network terminals (ONTs) to transmit voice, video and data throughout the network (Figure 1). POL uses internationally standardized systems called Gigabit PON (GPON) or Ethernet PON (EPON), but now GPON seems to be more popular, as GPON can offer higher performance and coexist with the legacy PON systems.

POL-composition
Figure 1. The Composition of POL

A POL solution needs nothing but passive components. Instead of using workgroup switches, the POL solution uses optical splitters which are the most important passive component of a POL system. Downstream, the splitter splits the signals to all the devices and upstream it combines them into one fiber, allowing bidirectional signals on one single-mode fiber. As shown in the following diagram (Figure 2. a typical POL diagram), signals are transmitted downstream at 1490nm and upstream at 1310nm. Downstream the splitter “splits” the signal for up to 32 ONT connections on only a single fiber each while upstream it “combines” the signals from the 32 ONTs onto the single fiber connecting the splitter to the OLT.

POL-diagramFigure 2. A Typical POL Diagram

Click here for a bigger version of the diagram

Without using electricity, optical splitters distribute converged services directly from main switch to the terminals that can achieve the maximum utilization of a single optical fiber cable and reduce power consumption at the same time. As the technology is becoming more and more mature, nowadays optical splitters (Figure 3.) can be designed as 64 outputs which greatly improves the utilization of optical fiber. To a certain extent, many IT techs consider the PON splitter to serve the same purpose as a switch but require no power / ground / AC(Alternating Current). And since there is no need for rack-mounted switches, it only takes a fraction of the space.

coupler&splitter
Figure 3. Nowadays Commonly Used Optical Splitters

Why POL is So Attractive?

POL is environment-friendly, less costly, easier to install and easier to maintain as well as more secure than legacy Ethernet networks. It is currently receiving increasing attention of people. Why many enterprises can’t afford to ignore POL? The following points will answer your question.

  • Optimized Bandwidth Handling – POL has the capability of dynamic bandwidth allocation which allows more users on the network and can offer a higher quality of service with reduced bottlenecks, slowdowns and downtime compared to a copper network’s dedicated bandwidth.
  • Security & Reliability – POL is adapted from telcom system that is designed for 99.999% reliability, at least 10 times than normal LAN components. Signals are encrypted downstream and systems that encrypt upstream and monitor fibers to detect tapping are available for high security areas.
  • Saving More – POL helps in saving the total cost of ownership (TCO) by a huge amount, as the cost of installation of the equipment is low. It uses the existing fiber optic cable and only the electronics are to be replaced, rather than replacing the whole infrastructure, which helps to save 75% of the expenditure. In addition, with its easy installation, we can save more on the labor cost.
  • Green and Environment-friendly – POL can dramatically reduce energy use and the consumption of plastic and metal materials as it requires much less cabling and infrastructure than a copper network, so that it can help enterprises reach sustainability milestones and certifications.
  • Better for Network Upgrade – Fiber eliminates the need for forklift upgrades of the cabling. With single-mode fiber harboring the ability to support data rates in excess of 60 Tbps (that’s terabit per second) over long distances, today’s fiber cable will likely carry us well into the future.

 

Summary

The POL offers the enterprise a more robust and durable alternative than copper structured cabling solutions, and it can help enterprises meet their network demands now and even for decades to come. POL can dramatically reduce both the installation and operating costs of your in-building Local Area Network (LAN). Using optical splitters and optical network terminals instead of access switches, POL provides connectivity to and throughout each floor of a building with low power consumption. It also enables a tremendous amount of network traffic over a reduced-footprint, lightweight optical cabling infrastructure and eliminates the electronics typically deployed at the access layer in traditional copper-based in-building networks. This is why POL is becoming more and more popular. According to a new market report published by Transparency Market Research, the global POL market is expected to reach USD 33.88 billion in 2020. We believe that POL will be more cost-effective and become more widely used by enterprises, govertments, campus etc., as the technology and passive optical component products market are becoming more and more mature in the next few years.


Related Recommendation: Fiberstore offers high-quality PON Splitters with 1×4, 1×8, 1×16, 1×32, 1×64, or 2×4, 2×8, 2×16, 2×32, 2×64 etc. configurations. For more information, please visit Fiberstore.com or contact us over sales@fs.com.

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