Passive Optical LAN Tutorial
With Passive Optical LAN gaining traction in all market verticals, now is the ideal time to learn more about this contemporary fiber-based networking technology.
Why install Passive Optical LAN?
Enterprise businesses that need to upgrade or replace existing telecommunications networks are looking for ways to improve energy efficiency and 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 fiber-based Passive Optical Networks (PON) technologies. Passive Optical Local Area Networks (POL) 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 end-devices connected.
Fiber delivers better investment protection with superior extended life
Fiber infrastructure is significantly more environmentally sustainable
Fiber in buildings and outside plant is technology independent
Fiber technology offers graceful migration from gigabit to 100 gigabits
Fiber cabling is more secure, reliable and has greater reach than copper
Fiber, such as Single Mode Fiber, has no known bandwidth capacity limits
How does Passive Optical LAN work?
Passive Optical LAN, or OLAN, is an IT infrastructure based on standards-based PON technologies (2.5G asymmetrical G-PON and 10G symmetrical XGS-PON) and standards-based advanced Ethernet technologies. The five (5) main pieces of an Optical LAN system include:
- Network Manager
- Optical Line Terminal
- Singlemode Fiber Cable
- Passive Optical Splitters
- Optical Network Terminal
The Passive Optical Network (PON) Manager (i.e. Element Manager) is the centralized intelligence and management of the passive optical network elements and subtended powered devices (i.e. powered devices). The PON Manager provides the one console and one screen control to orchestrate consist, repeatable, error-free IT policies and procedures through global profiles. This is the user interface that IT staff will access to perform faster network provisioning, configurations, moves, adds, changes and troubleshooting.
Optical Line Terminal (OLT)
The OLT is typically located in the building’s main data center and provides aggregation plus distribution of the enterprise network connectivity. A single OLT can be sized to support from 200 Ethernet connections to over 7,000 Ethernet connections from one location. It is the OLT that is connected to the Wide Area Network (WAN) and all internal resource servers through the core router. An OLT can be one rack unit in height (1 ¾ inches) to four rack units high (~ 6 inches) and even with the inclusion of powering equipment and fiber management typically all fits in one telco rack. Today’s OLTs support both Passive Optical Networking service modules that allow XFP selectable ITU-T 984 G-PON 2.5G or ITU-T G.9807/G.987 XGS-PON symmetrical 10G connectivity down to the ONTs.
Singlemode Fiber (SMF)
SMF is the fiber optic cabling that runs throughout the building’s risers and pathways. It is the SMF that physically connects the OLT, splitters and ONTs. That said, it should be noted that there are options for operating PON over multimode fiber (MMF) and there are closet-based ONTs that can leverage the last 300’ of copper-cabling. There is also the choice of installing composite SMF cabling that includes two copper wires within the cabling jacket for remote powering of the ONTs.
Passive Optical Splitters
Optical splitters provide the point-to-multipoint connectivity between the OLT and the ONTs. The splitters offer flexible mounting in telecom closets, wall enclosures or ceiling enclosures. They offer split ratios from 1:2 up to 1:64 with the most common split ration being 1:32. Optical splitters also provide equipment, fiber and services protection through 2:X redundancy options. They are unmanaged, unpowered and highly reliable.
Optical Network Terminal (ONT)
ONTs enables optical to electrical conversion and Ethernet connectivity for voice, video, data, Wi-Fi and all other digital enterprise services and devices. ONTs are Power over Ethernet (PoE) enabled and subtend other powered devices (e.g. phones, cameras, wireless access points). ONTs themselves can be either locally powered from a nearby AC outlet, or remotely powered from a DC source. ONT mounting can be located above the desk, below the desk or can be nearly flush-mounted in the wall. They can also be mounted in zone boxes, with optional plenum brackets and in raised floors. Finally, there are also options for rack-mounted 48-port Ethernet ONTs that provide an economical one-to-one replacement of traditional closet-based Ethernet switches that can continue to utilize the last 300’ copper cabling drops inside a building.