How enterprises are solving network challenges with Passive Optical LAN

by | Sep 27, 2018 | White Paper

Passive Optical LAN white paper

Enterprise businesses that need to upgrade or replace existing local area networks are looking for ways to improve reduce capital and operating expenses. Technology managers are looking for solutions that furnish high bandwidth while increasing the security and reliability of their networks.

To meet these requirements, enterprises are turning to Passive Optical Networks (PON), also known as Passive Optical LANs (POL). Passive Optical LANs provide enormous value to enterprises without forcing them to alter how they do business, while existing services provided by their networks remain the same with no change to core and user devices.

Additionally, enterprises are saving up to 30%–50% of capital costs, 50%–70% of ongoing operational costs, and 90% of the rack space while exceeding network security and reliability goals. Plus, businesses deploying Passive Optical LANs experience long-term savings by future- proofing their network infrastructure while realizing all of the benefits of converging their networked services, including voice, video, wireless access, security, surveillance, building environmental controls and building automation with Power over Ethernet (PoE) where needed.

This white paper explains how Passive Optical LANs work and how they can benefit your organization. It also highlights why enterprises are looking to deploy Passive Optical LANs solutions that solve evolving network challenges by:

  • Delivering CapEx and OpEx savings
  • Reducing space requirements
  • Deploying a future-proof infrastructure
  • Converging all enterprise LAN services
  • Smoothing upgrade to next-generation speeds
  • Designing and building better network reliability
  • Improving security by reducing points of vulnerability


Passive Optical LAN vs. traditional copper-based LAN
A Passive Optical LAN is a Layer-2 transport medium, built with Passive Optical Network (PON) technology, which provides converged video, data, wireless access and voice services at gigabit speeds over a single strand of fiber to the user’s location. Comparing the configurations of a traditional copper-based LAN and a Passive Optical LAN architecture helps to illustrate more clearly the similarities between the two technologies.

In a traditional copper-based LAN, a router in the top-most layer (Core Layer) links to the campus or building aggregation switches (Distribution Layer) below. The distribution switches connect down to the Access Layer switches in the communications closets. Copper cables extend from the communications closets to the users and end devices.

In a Passive Optical LAN solution, the router is retained in the top-most layer, and the Optical Line Terminal (OLT) serves the same purpose as the campus aggregation switches. The building aggregation switching is accomplished by the 1×32 (or 2×32 for equipment redundancy and fiber route diversity) optical splitter, which is a passive device, so there are no power requirements and little management while being highly reliable. The Optical Network Terminals (ONT) provide connectivity to the users and end devices.

It is important to note that both solutions provide data access via Ethernet connections to the user and devices Therefore, no client or PC reconfiguration is required when upgrading to a PON infrastructure. Enterprises also have the flexibility to deploy a Passive Optical LAN in a fiber-to-the- desktop topology or a fiber-to-the-communications room. A splitter-equipped fiber distribution hub (FDH) on each floor routes the fiber to the desktop ONTs throughout the building. The fiber-to-the-communications room topology allows for the reuse of existing copper cables between the communications closets and the desks.

A Passive Optical LAN’s ONT has all of the required Layer-2 functionality built in. The Passive Optical LAN provides integrated Ethernet bridging, the VLAN capability required for network segmentation, and user authentication and security filtering. The ONT, which functions much like an Ethernet switch, makes it possible for an enterprise to seamlessly replace an Ethernet-switched LAN.

Deliver significant CapEx and OpEx savings
When upgrading your network infrastructure, it is important to look at both the near-term and long-term expenses. Today’s enterprises require solutions that not only lower initial capital expenses but also reduce the total cost of ownership (TCO) for the network. Forward-looking managers insist that new systems address more of their modern connectivity requirements while minimizing ongoing operational expenses.

Passive Optical LAN technology enables the enterprise to significantly reduce the cabling infrastructure costs from the data center to the user by significantly reducing the number of cable runs. The result is a decrease in overall operational costs and network complexity.

Each ONT model supports multiple densities of Gigabit Ethernet, POTS and RF video. This integrated approach provides the ability to connect building automation systems, security cameras and building sensors all on the same infrastructure, thereby removing the requirement and expense of separate transport systems across the campus for each technology. The PON infrastructure also eliminates costly hardware within a network, such as remote switches, as well as their associated provisioning cost, annual maintenance and software licensing fees.

A Passive Optical LAN extends the network life cycle to 10 years or more. This approach enables:

  • Gradual, more predictable costs for bandwidth upgrades over the full 10-year period
  • Modest ongoing maintenance costs associated with fiber
  • Seamless addition of more technology-based capabilities, such as wave division multiplexing 40- and 100-Gbps transport and terabyte switching

Developed for low-cost fiber-based converged network service delivery, G-PON standards were finalized by the ITU in 2003 (ITU G984.x). Tellabs first publicly demonstrated standards-based G-PON OLTs and ONTs to the North American service provider consortium led by Verizon, AT&T and BellSouth in May 2006.

Today, the growing market acceptance reflects Passive Optical LAN’s ability to support critical enterprise applications with greater efficiency than traditional copper-based LANs.

Reducing space requirements

Cutting back on floor, rack and closet space is also extremely important to organizations looking to save. Reduction in floor space lowers operating expenses by reducing overhead costs, such as fire safety, security and HVAC. In addition, the smaller footprint associated with Passive Optical LAN technology enables next-generation performance and services in smaller communication closets not originally designed for advanced communications equipment.

A typical copper-based LAN serving up to 2,016 users requires 90 rack units of space. Active Ethernet LAN switches require one full rack for the switches and two additional racks for terminating the large bundles of copper cables associated with the switches. The total solution would require a total of 18 seven-foot-tall equipment racks. Comparatively, a Passive Optical LAN serves up to 7,700 users. Due to the OLT’s 90% greater density, this solution requires only 1 equipment rack and a total of 9 rack units within the rack.

Additionally, a Passive Optical LAN requires fewer communications closets and, in some cases, eliminates them altogether. As a result, a business can recover physical space and cut expenses. The single-mode fiber in the Passive Optical LAN, however, can reach up to 30 kilometers. This enables an enterprise to:

  • Reduce or eliminate repeaters, switches and communications closets
  • Deploy an OLT in a single central location

Deploy a future-proof Infrastructure
Installing a singlemode fiber (SMF) infrastructure virtually future-proofs your network. Since SMF has been demonstrated to carry 101 Tbps of full duplex bandwidth, the next-generation network upgrade will not impact the installed fiber distribution network, and you will only need to upgrade the electronics. Utilizing SMF extends the LAN reach out to 30 kilometers without signal regeneration.

Typically, the cable plant is the most expensive part of a technology upgrade. Installing SMF removes the requirement for additional upgrades to your cable plant in the foreseeable future. Additionally, recent advances in fiber connector technology have reduced the cost of installing fiber significantly, and in most cases the installation of fiber is now less labor intensive than installation of a copper cable plant.

In a direct comparison to CATx copper cable plant, SMF is smaller, lighter and stronger; has a tighter bend radius, higher bandwidth capacity and longer reach; is less susceptible to EMI interference; has faster connector solutions and longer life; and entails less material expense than CATx.

It should be noted that there are options for deploying Passive Optical LAN over multimode fiber (MMF) cabling. In the case of retrofits of existing networks, this allows for substantial cost savings in time, and money, for utilizing existing MMF cabling that may already be present in building risers, horizontals, and pathways.


Converge all enterprise LAN services
Converging all network services is the foremost feature of the Passive Optical LAN. It will converge all services across a single infrastructure, eliminating the need for multiple platforms while providing highly scalable high-speed data services to all users. Additionally, voice (e.g., analog POTS and VoIP w/PoE), video, video conferencing services, wireless access and monitoring services (e.g., building automation system, security cameras and building sensors) are all supported on the Passive Optical LAN.

Voice — Providing the same services as a legacy switching architecture, VoIP handsets are connected at the ONTs via a standard RJ-45 gigabit Ethernet port. The VoIP service is transported to IP PBX or softswitch as standard IP/Ethernet traffic.

Passive Optical LAN OLTs and ONTs can also support analog voice, or what is commonly called Plain Old Telephone Service (POTS). In this scenario, the ONT itself contains a Session Initiation Protocol (SIP) to the analog converter that allows the POTS phone to plug into an RJ-11 port on the ONT. As the ONT converts the POTS call to SIP, it is transported over the Passive Optical LAN system in a VoIP format, which is handled in one of two ways. The first option is to convert the call back to analog with a voice gateway (VGW) that provides legacy PBX integration or tip/ring lines from the carrier. The second approach ties the POTS phone as a SIP call directly to a VoIP extension on the customer’s IP-PBX or softswitch, eliminating the need for voIP phones to be purchased. Both options provide full integration with the features of the legacy TDM PBX, POTS lines or the VoIP softswitch, and deliver call waiting, message waiting indicator lights, voicemail and all other features to the user via the analog POTS handset.


The ONTs do support IEEE standards for IEEE 802.3af PoE (15.4 watts at an Ethernet port) and IEEE 802.3at PoE+ (25.6 watts at an Ethernet port) to power the voIP handsets. regardless of the solution being deployed (VoIP or POTS services), the Passive Optical LAN system provides the necessary network protocols and quality of service (QoS) required in the modern enterprise environment. This allows for VLAN trunking and creating “daisy chained” PCs fed off of the VoIP endpoint with a separate VLAN and QoS settings for each achieved via standards based on IEEE 802.1q and Differentiated Services Code Point (DSCP) mappings that guarantee that the voice calls are clear.

Video — Since Passive Optical LAN is a standard transport system, IP video content can be deployed with little effort. As an example, small enterprises are able to encode off-air analog and digital channels, and deliver them in both standard definition and high-definition quality. These video networks are built to support local cached content for video on demand (VoD) and other interactive services. There are even options for local content insertion (e.g., facility news, company news and training). This is accomplished over the Passive Optical LAN equipment, since the video is once again transported in an IP/Ethernet format. As the Passive Optical LAN system leverages Internet Group Management Protocol (IGMP) multicast delivery mechanisms, it is a highly efficient means to deliver video on the network. IGMP multicasting takes place across the OLT and ONTs so as to ensure that only a single copy of the unique IP video stream is efficiently sent across the network, optimizing bandwidth. This same architecture can support enterprise-centric IP video, such as video conferencing (VTC), telepresence conferencing, telepresence robots and video surveillance.


Identical to voice services on the Passive Optical LAN, strict QoS preserves the video content and priority in the network. This is especially critical in video conferencing (VTC) and in telepresence applications. The video is delivered through rate limiting (shaping), queue management (buffering) and scheduling (policing) mechanisms. Bandwidth rate limiting is set by provisioning the sustained data rate levels and burst or peak rate for proper traffic shaping. Finally, the OLT and ONT queue (buffers) and scheduling (policing) smooths any bursty traffic. All of the above together builds your service level agreements (SLAs) that ensure that the IP video quality is high and the user experience is superior.

If there is RF video, Passive Optical LAN provides video overlay service in compliance with ITU-T G.984. The RF video is carried on the system using a third wavelength (1550 nm). The video signal format delivered to the customer is defined by SCTE standards. From the ONT, a standard 750-ohm coaxial interface supports 54–900 MHz CATv channel content. Since this is accomplished over a separate wavelength, the RF video network equipment is not aware of the Passive Optical LAN presence. With the centralized management of the Passive Optical LAN, the coaxial output can be tuned to match the signal levels required for the customers remotely and allow for remote balancing of the network.


Wireless — Passive Optical LAN can also be used to backhaul wireless access points traffic. It can do so in two architectures. First, there is the stand-alone static Wi-Fi architecture with no robust controller functionality. In this scenario, Passive Optical LAN can provide the benefits of lower equipment cost, reduced energy and collapsed cabling infrastructure. There are also wireless access point (WAP) features and functionality integration that can be accomplished with POL via the centralized management platform. POL provides a greater system reach for improved performance and coverage for Wi-Fi service. As POL interoperates with established Wi-Fi vendors (e.g. Cisco, Meraki, Ruckus, Aruba, Meru, etc…) it allows for Wi-Fi controller functionality to be provided by best of breed Wi-Fi manufactures without limiting the customer’s options. The controller functionality adds dynamic provisioning, interference correction, load balancing and coverage optimization as is required in a true enterprise deployment.

There are also synergies between Passive Optical LAN, Distributed Antenna Systems (DAS), Small Cell, future 5G cellular readiness and fiber optic cabling. To be clear, the cellular traffic does necessarily traverse the POL equipment, but it can leverage the same fiber infrastructure that POL utilizes. Alone, indoor enterprise cellular networks have a challenging return-on-investment analysis – it is relatively expensive, it only does one thing and the end customers think they should not have to pay for it. POL has an excellent ROI that can justify the deployment of indoor cellular over existing fiber plant inside buildings and across a campus. One thing is certain, these next-generation enterprise cellular network solutions are not going to be supported on, nor their traffic backhauled over, copper-based CATx cabling. Thus, investments in fiber optic cabling is protected even relative to future demands of indoor enterprise cellular networks advancements.
It should be noted that the ONTs do support IEEE standards for 802.3af PoE, 802.3at PoE+, and 802.3bt 4PPoE to power the Wi-Fi WAPs. These ONTs provide Powered Device (PD) management, monitoring and configuration using Link Layer Discovery Protocol (LLDP) too. Thus, the ONT detects the actual power requirements of a PD and then adjust the power allocation for that PoE port. There are also mechanisms for providing reports on power consumption so that IT managers may adjust deployment configurations to low-power modes for devices like WAPs and IP phones alike.

Smart/Intelligent Buildings — Today there is a recognized need to design and build an IT network infrastructure that supports thousands of digital services and connectivity. That same LAN also needs to have the flexibility to expand as thousands of additional gigabit Ethernet connections are added over time as the sheer number of digital devices grows exponentially. This is the same problem statement faced IT professionals around the world as they prepare to support the network demands of smart intelligent buildings and the inevitable impact of the IoT. In a traditional IT network design, this rapid connection growth mean racking and stacking Ethernet switches in telecommunication rooms and running point-to-point copper cabling 100 meters to every connected device. Every time you added the complexity of more electronic switches and copper cables you negatively impact energy, thermals, reliability, security and especially environmental green programs. This is not a sustainable business nor sustainable green approach.

Passive Optical LAN is ideal handle the digital transformation of enterprise business and their buildings. POL network design ensures IT professionals a gracefully and cost effectively means to grow their network connectivity in response to smart building IoT demand by leveraging the Optical LAN system and cabling superior capacity. POL relies on Single Mode Fiber (SMF) cabling from the main data center through the cable risers, through the horizontal pathways and as close to the digital devices as possible. SMF cable bandwidth is tremendous and is measured in terabits today – far greater than copper cables measured capacity in the gigabits. With this inherent capacity, SMF lifespan is expected to exceed 25 years whereas copper cables historically have been ripped and replace every 5-7 years. Similarly, the Optical LAN system and passive optical splitters already provide a graceful migration to 10G, 40G and 100G capacity with no conflicts. Optical LAN has greater gigabit Ethernet density (in smaller footprint) and scalability to support thousands future smart intelligent building (e.g. IoT). Finally, POL has centralized intelligence and management to manage the thousands of IoT connected devices in more M2M and plug-n-play manner.

Building Management System (BMS) and Building Automation System (BAS) are extremely important for any new high-performance buildings and a key to reducing operating costs. Building monitoring devices and system reporting and analysis tools require IP/Ethernet connectivity. In recent years, the POL has taken on the responsibility to integrate these functions. Since most BMS/BAS monitoring devices today are IP/Ethernet-based, the connectivity into the existing (or new) POL is seamless. The POL can ensure adequate bandwidth, security, authentication, and quality of service specific to each monitoring and management devices.


Smooth upgrade path to next-generation speeds

Passive Optical LAN is currently based on Gigabit-PON, or G-PON, which provides the capacity of 2.5 Gbps in the downstream direction and 1.2 in the upstream direction. It follows Full Service Access Network (FSAN) recommendations that are ratified and published within ITU-T G.984 standards. G-PON is widely deployed supporting millions of end users around the world. Next up is the industry work is being focused on a collection of architectures under consideration for XGS-PON and NG-PON2. ITU-T G.989 will support both XGS-PON (symmetrical 10G) and NG-PON (40G). NG-PON2 is inclusive of 40 Gbps PON and WDM PON versions and is progressing through the standards adoption process within the ITU-T G.989 framework.

All of the above PON, whether 2.5G, 10G and 40G have no wavelength conflicts and can be deployed over today’s SMF cabling, optical splitters, fiber management enclosures and powering infrastructure. These facts answer the “why” and the “how” Passive Optical LAN helps an enterprise future-proof their network infrastructure.


Singlemode Fiber (and multimode fiber too) — Compared to copper cabling, singlemode fiber is smaller, lighter and stronger with a better bend radius and longer reach. It is less susceptible to interference, has faster connector solutions and a longer life, and is more secure and less expensive. On top of all of those great benefits, fiber cabling also has higher bandwidth capacity, with upper thresholds that are only limited by today’s technology. That means that the current generation OLAN OLT, optical distribution splitter and SMF cabling will not need to be replaced when the time comes to upgrade the network to next-generation Passive Optical Networking technology in support of 10 gigabit and 40 gigabit speeds.

As noted earlier, there are options for deploying Passive Optical LAN over MMF cabling which allows for substantial cost savings in time, and money, for utilizing existing MMF cabling that may already be present in building risers, horizontals, and pathways.


Designing and building better reliability with higher network availability

Passive Optical LANs provides enterprise LANs with superior stability, high availability and industry-leading network uptime. This is accomplished with carrier-class componentry, equipment redundancy, dual homing to wide area network, route diversity in fiber cabling infrastructure and redundant OLTs in geographically dispersed locations.


Route diversity in fiber cabling infrastructure – A single OLT can be equipped with a redundant PON port or PON card serving one ONT with two paths across a redundant optical plant. This PON equipment-level redundancy, from one OLT, is a means to provide fiber route diversity using the FSAN ITU standard Type-B PON redundancy option. Type-B PON redundancy is a purely passive solution, defined in principle by FSAN ITU standards, and is contingent on deploying 2:x Passive Optical splitters. These highly reliable 2:x optical splitters provide both protection, redundancy and splitting functions in the optical plant. CIOs and IT pros have a great amout of flexibility as to where these splitters can be placed in their optical plant infrastructure. For example, the 2:x Passive Optical splitters can either be positioned for centralized (e.g. near the data center) or distributed (e.g. far from the data center) architectures. These 2:x passive optical splitters support a variety of split ratios, including 2:8, 2:16 and 2:32, dependent on the type and number of ONTs being subtended. They can be sourced from major Layer-1 optics manufacturers.


Geographically dispersed OLTs – Two OLTs at geographically dispersed locations can also be configured to serve one ONT with two paths across a redundant optical plant. Because of this, Type-B PON redundancy provides options for fiber route diversity to different PON ports in the same OLT, different PON cards in the same OLT, and different OLTs in geographically dispersed locations. The use of redundant OLTs in two locations represents the pinnacle of reliability being 99.9999%, as six-nines network availability is the culmination of all redundancy options, including dual homing routers, equipment redundancy and Type-B PON redundancy with fiber route diversity and geographically dispersed OLTs.


Improve security by reducing points of vulnerability

A secure LAN starts with system-wide centralized intelligence, control, automation and management. Within the POL Element Management Systems (EMS), role-based access for users is established through strict authentication and authorization. This is where secure passwords are assigned and managed. Based on IT staff credentials, privileges are defined for what a user can view and modify. Then the activity of the IT staff can be tracked, which helps root cause analyses during trouble-shooting and can help with junior IT staff training. User management is very important for achieving the highest levels of security, stability and operational efficiencies. The POL EMS is where secure global profiles are created for ONTs, ports, connections and other network elements. Within these secure global profiles consistent policies and procedures can be ensured. Information managed within these global profiles include the ONT identifier and name, Ethernet port configuration, PoE, LLDP, NAC, 802.1x, and other settings, which are configured as autonomous rules-based provisioning.

The fiber cabling infrastructure can make significant contributions to overall security. Fiber optic cabling is more secure than copper cabling. Fiber is not susceptible to interference nor does it introduce interference. With fiber you have no cross-talk, no EMI, no RFI and no EMP. The opposite is true of copper cabling, which allows radiate emissions that can be eavesdropped without physical access. You cannot “listen to” fiber from any distance, and one would need to physically access fiber to gain entry to fiber-based communications. Physically tapping fiber is tremendously difficult, taking into consideration the expertise and equipment that would be needed. In the end, PON uses a stateful protocols that will detect all abnormal, rogue and intrusion events, so the physical tapping event will be thwarted.

The Passive Optical LAN ONTs are inherently secure as well. POL ONTs are designed with no local management access. This is done because there are few needs for human touches at the ONTs. The ONTs are basically simple optical-to-electrical terminals. ONTs are highly secure and reliable, which ultimately helps improve security. Furthermore, Optical LAN has centralized intelligence and management; no information is stored at the ONTs. That is, user and provisioning information does not reside on ONT. ONTs are a thin client — user/device policies are managed solely at the OLT. Thus, ONTs can move freely around the LAN and be sent back to the manufacturer for repair/return without the risk of network/user data being compromised.



Enterprises looking to upgrade or replace their network infrastructure are realizing the value of Passive Optical LAN. Passive Optical LAN provides significant benefits without forcing enterprises to alter what they are already doing, or changing out the core and user devices. Businesses are saving up to 30%–50% of capital costs, 50%–70% of ongoing operational costs, 30%–65% on energy and 90% of the space while exceeding network security and reliability goals.

Deploying a Passive Optical LAN helps an enterprise future-proof their network infrastructure while realizing all of the benefits of converged network services. The Passive Optical LAN provides solutions that furnish high bandwidth while increasing the security and reliability of existing networks.

John Hoover

John Hoover

Marketing Director

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