Flexible Design Choices With 10G Passive Optical LANs

by | Jul 23, 2019 | Featured, White Paper

Passive Optical LAN

Passive Optical LAN better aligns space, energy, heat, noise, radiation, and costs, with your true bandwidth requirements for IoT, smart building, cloud and wireless.

The useful life expectancy of traditional enterprise LAN infrastructure is regrettably short with Ethernet switches, and copper cabling, historically being around 5-7 years. Even more alarming is how quickly wireless technologies is evolving in the 3-5 years range. At each one of these transitions, the switch and cable manufacturers expected you to completely rip-and-replace your hardware and infrastructure (e.g. CAT3 to CAT5 to CAT7, etc…).

Every time higher bandwidth, like 10-gigabit, is introduced, it causes disruption in the LAN. The new equipment and cabling has different connectors, it occupies greater space, consumes extra energy, emits additional thermals, introduces greater noise, crosstalk and radiation, and it costs more money. Yet, this time around with 10G, not all services, devices and users truly require 10Gbps. In fact, the Microsoft’s recommendation for the modern enterprise optimize user experience to the cloud is 512Kbps. Further aggravating the situation, traditional switch vendors are complicating matters these days by increasing network complexity, day-1 capital cost and year-over-year operational expenses.

So, how can you align space, energy, heat, noise, radiation, and costs, with your true network bandwidth requirements?

The answer is a Passive Optical LAN design that gives you greater flexibility to right-size connectivity across the enterprise LAN – inside buildings and across an extended campus. Optical LAN better aligns space, energy, heat, noise, radiation, and costs with your real bandwidth requirements, which honestly is not going to be 10Gbps to everything.

Optical LAN provides flexible design across the end-to-end enterprise LAN that traditional design simply cannot, such as choices for:

  • Management
  • Data Center
  • Infrastructure
  • Closet-Based
  • Deep Fiber

The truth is 10 Gbps is not needed everywhere in the enterprise network. Furthermore, the local area network (LAN) users, services and device bandwidth through-put is ultimately limited by the wide area network (WAN) connection. In fact, most users, services and end devices utilize far less bandwidth in the Mbps and Kbps range. Thus, “right-sizing” the network means providing flexible connectivity options for 1M, 10M, 100M, 1G, 2.5G, 5G and 10G in the most efficient and cost-effective manner – a Passive Optical LAN design can do just that.


A Passive Optical LAN has centralized intelligence and management. Therefore, from one screen you can manage the entire end-to-end connections as one virtual switch. This allows for virtual Ethernet port extension across an Optical LAN with software defined LAN agility and automation. That is, one can manage the network resources, in software, and dynamically allocate those network resource based on real-time needs. This is accomplished with global profiles. The global profiles orchestrate error-free, and more secure, operations. Finally, the OLAN management interface itself can be a choice between desktop, laptop, smart phone and cloud-based for either G-PON and 10G PON virtual Ethernet port extension – and for both closet-based and deep fiber ONTs.

Data Center

The Optical Line Terminal (OLT) will likely be located in the main data center. The purpose of an OLT is to act as a distribution and aggregation switch for the entire enterprise network. An OLT can provide greater connectivity density in a smaller footprint than a traditional network design.

Right sizing 10-gigabit connectivity inside buildings, and across a campus, starts at the OLT. The OLT can be equipped with either 2.5G G-PON (ITU-T G.984) or symmetrical 10G XGS-PON (ITU-T G.9807) ports. By simply picking the appropriate XFPs, one can fine tune how many PON ports at the OLT truly need to be either 2.5G G-PON or 10G PON. Best yet, the OLT hardware is ready for 25G PON and/or 40G NG-PON, so you will not require a rip-and-replace if those speeds are actually needed in the future.


There are many design choices that can be accommodated through-out the network infrastructure that directly impact engineering proper capacity for both high bandwidth and low bandwidth connectivity, including:

  • WDM Combiner
  • Splitter Positioning
  • Splitter Split Ratio
  • Network Uptime
  • Fiber Cabling

WDM Combiner – This Wave Division Multiplexer (WDM) combiner can be utilized if G-PON and 10G PON are on the same fiber cable and optical splitter. In the future there are no foreseen wavelengths conflicts, thus NG-PON2 can be deployed over today’s infrastructure – this ensures that as bandwidth increases no rip-and-replace will be necessary. Optionally one can also segregate G-PON and 10G PON on separate physical infrastructures. This can be accomplished by simply designating different optical splitters to be either G-PON or 10G PON.

Splitter Positioning – Because of Optical LAN’s many options for ceiling, floor, wall, MDF or IDF optical splitter placement, one can completely exit, and eliminate, the telecommunications closet. This is not always the case, but there are situations where building architects can take advantage of this ability. One can also choose centralized (e.g. close to data center or in data center), distributed (e.g. pushed out deep in the network) or cascade splitters (e.g. 1×4 splitter connects 1×8 splitters) depending on fiber availability, and space constraints in the buildings cable risers, horizontal, pathways and drops.


Splitter Split Ratio – With the availability of symmetrical 10G XGS-PON, optical splitter split ratios become even more advantageous for leveraging anything from 1×2 to 1×64. Now more than ever you can match actual bandwidth requirements with optical split ratio. For example, when designing for IoT and smart building device connectivity, one can deploy a high 1×64 split ratio. And, for deploying high bandwidth devices, such as IP Cameras and WAPs, one can utilize low 1×8 split or 1×16 split in order to dedicate more bandwidth to the services, users and devices that truly need the extra capacity.


Network Uptime – Traditional LAN design has established a very low standard for network availability at 99.9% network uptime (e.g. over 5 hours of annual network downtime). Even a simplistic Optical LAN design can achieve a better 99.999% network uptime (e.g. around 5 minutes of annual network downtime), which can be OK when critical services, users and devices are NOT connected and when day-1 capital costs want to be minimized. However, more often today’s contemporary networks require always-on connectivity 7/24/365. That is, network downtime directly correlates to lost revenue, lost productivity and security vulnerabilities. This is why most Optical LAN infrastructure designs chooses the optional support of Type-B PON Protection for the greatest 99.9999% uptime (e.g. less than 30 seconds of annual network downtime). Type-B PON protection provides redundant connectivity to OLT ports, OLT cards and geographically separate OLTs – this also allows for fiber cabling route diversity and ultra-high network reliability.


Fiber Cabling – Even in the situation where there is existing multimode cabling already in the building riser, horizontal or pathways, there are choices that support Passive Optical LAN over either multimode or singlemode cabling. Flexible choices exist that support OLAN over OM1, OM2, OM3 and OM4 fiber cable types. These SMF to MMF options are passive, so these multimode fibers continue to be highly reliable, require no monitoring and no maintenance. In fact, Optical LAN can uniquely deliver 10-gigabit over multimode fiber cabling further (up to 550m) when compared to traditional LANs options.


If a customer chooses to leave the last 100 meters of copper cabling in place, and not touch the final access drops, then closet-based ONTs can be chosen. In fact, with a 48-port 10G PON ONT, you can perform an economical one-to-one closet-based workgroup switch replacement – power, cable, and cable management, all stays the same. This closet-based ONT switch replacement offers a break from the inherently flawed, and ever-growing complexity, and increasing costs, of the status quo traditional LAN design. This architecture allows customers to gain the advantages of OLAN vastly improve operational efficiencies, greater security, and reduced technical refreshes, without disrupting the last stretch of copper cable in the workplace. Less fiber cabling is needed in the data center, risers, horizontal and telecom closets, since the closet-based ONTs reduce uplink cabling (e.g. multiple bidirectional wavelengths on single fiber) compared to traditional workgroup switch footprint. Furthermore, the closet-based ONTs provide a graceful migration, by means of an intermediate step, towards optional deep fiber ONTs LAN design – especially for renovations, upgrades, and additions at existing facilities (e.g. brownfield). It also warrants noting that these closet-based ONTs are environmentally hardened, and have a temperature range from -5°C / +23°F to +55°C / +131°F – thus, the year-over-year HVAC costs can be reduced, or eliminated, where it is installed.

Deep Fiber

Extending fiber connectivity, as deep as possible, inside buildings, and across a campus, is ultimately best as it allows enterprise LANs to fully realizes the undeniable fiber cabling benefits. Deep fiber ONTs have a wide array of mounting choices, such as wall, floor, ceiling, desk, furniture and they are fully plenum rated. Theses ONTs can be either G-PON, or 10G XGS-PON. This is a very important point, as this allows for the cost effectively focus G-PON ONTs for x<1Gbps connectivity for IoT and smart building applications. Conversely, it also allows for the symmetrical 10G ONTs (bi-directional encryption) to be added strategically only where x>1Gbps capacity is truly needed – perhaps for WAPs and IP cameras. For example, 10G PON, with the 5-port 10G ONTs, you can connect multiple Wi-Fi 6 (IEEE 802.11ax) devices, using the 2.5G interface from multi-rate SFP+, and transmit over 10G PON, and the math perfectly aligns with the available bandwidth (e.g. 4 x 2.5G = 10G).  This optimization is possible because the 10G PON ONTs support virtualized Ethernet port extension from multi-rate 1G, 2.5G, 5G or 10G SFP+ choice – not all the way from back at the closet (e.g. 100 meters), but as close to the end-points as possible (e.g. a couple of meters). This means that bandwidth can be exactly matched at the final connection to the enterprise service, user or device – this is a far more efficient network design that traditional LAN footprint can’t replicate.

Flexible design choices with 10G OLANs for the management, data center, infrastructure, closet-based ONTs and deep fiber ONTs

A Passive Optical LAN design provides greater Ethernet density in a smaller footprint for IoT and smart building connectivity. It delivers end-to-end QoS ensures better user experience for cloud-based and OLAN as a Service. It can connect four Wi-Fi 6 (IEEE 802.11ax) at 2.5G over 10G perfectly aligns with 4-port ONTs. Finally, it is very important to note that single mode fiber, 25G PON and 40G PON, are leading choices for future 5G wireless infrastructure.

To ensure the enterprise network architecture properly aligns space, energy, heat, noise, radiation, and costs with your actual bandwidth requirements, a Passive Optical LAN design puts flexible choices in the hands of Architects, Engineers, Consultants and IT staff. To accommodate the low bandwidth connectivity needs like IoT, smart building and office workplace – choose low cost G-PON ports at the OLT, and G-PON ONTs, along with utilizing higher optical split ratio (e.g. 2×64). For the high bandwidth needs like IP cameras and wireless – choose 10G PON ports at the OLT, and 10G PON ONTs with multi-rate Ethernet, and then consider lowering the optical split ratio (e.g. 2×16) to support the additional capacity required.

Thus, a Passive Optical LAN design does gives you better choices to right-size connectivity inside buildings and across a campus. It optimizes space, energy, heat, noise, radiation, and costs with your true bandwidth requirements.

John Hoover, Tellabs Marketing Director
John Hoover
Director of Marketing
John Hoover is a Marketing Director at Tellabs and 2024 Board Chair of the Association for Promoting Optical LAN (APOLAN). Over the past 20 years, John has influenced industry milestones such as early passive optical network deployments, video implementations, wireless and more recently enterprise Passive Optical LAN adoption.