An Intriguing Networking Choice: Passive Optical LAN (POL)

S. J. Schuchart Jr.

The networking journey is always one of change. Yet there are some technologies that we’ve used for literally decades that are showing signs of being less than up to the challenges of growing bandwidth and device density. Indeed, new services such as Wi-Fi 6 are driving the need for more bandwidth, especially on the backhaul. Copper Ethernet cables are a great example of where a great technology is beginning to run into the harsh limits of physics. To achieve even 10 Gigabit speeds excessive care has to be taken with thick, less flexible cables and distance limits of 100 meters for properly installed cabling systems (Cat6a or Cat7). With bandwidth rising to 40Gbps and 100Gbps and beyond, it becomes a matter of much discussion on how we support networks going forward, especially in new construction. Nobody wants the expense of upgrading a building’s network cabling within a few years of finishing it.

One of the interesting alternatives out there is called POL or Passive Optical LAN. POL is a subset of optical networking technology under the greater umbrella of PON (Passive Optical Network). These technologies are tested and have been in use for a long time, mostly in Fiber to the Home installations, metro installations, and large campus installations. We are not going to go into all the variations of PON, there are a bewildering array, but confine the discussion to POL and enterprise use cases. POL itself has been around for quite a while too, but never really took off, but there is reason to believe that now POL could become a great alternative to traditional designs for enterprises.

Let’s dive down a little bit into what we mean by POL. POL uses passive optical cabling, single mode fiber. Passive means that only the source and receiver require electrical power. The optical splitters in between are unpowered, which makes them less expensive, less prone to failure, and do not require battery backups. Plus, they can save considerable power vs. active solutions. POL networks can be used for several purposes, such as carrying data, video, and phone services on separate strands of the same optical cable.

The first question most people ask when they understand POL is a simple “why” while looking at the optical links available on campus switches. The answer to that comes down to a simpler optical system, upgradability and reliability. POL networks do not have the failures associated with pluggable optical transceivers, which are both expensive and fragile. Lastly, the POL network is upgradable in place far in excess of what can be done with copper, with new speeds available with minimal costs compared to traditional networking designs.

There is more as well. In marine or marine adjacent environments, POL offers a non-corroding alternative that is impervious to the salt air. Plus, POL can be used at distances up to 20km. This makes POL a great choice for if you are administering a campus for connecting buildings, setting up video security, and connecting campus-wide Wi-Fi. POL makes these functions easier to both install and to maintain long term. Companies are also increasingly aware of operational efficiencies. POL networking, due to its simple nature is much easier to administer, even on a large campus. Companies considering POL should select a vendor that either sells both the POL and Ethernet solution and has management under a single pane of glass or select a POL vendor that has done the necessary integration with your existing Ethernet networking solution.

The ripest targets for POL are generally new construction and historical structures. For new construction, planning and installing an optical fiber network that should have a functional life of decades is an easy choice. For historical structures where there can be no or extremely minimal changes to the structure, POL offers a long life and fairly small cabling to minimize the compromises that need to be taken. Existing brownfield environments can be retrofitted for POL, but often the costs of installing optical cabling in spaces not designed for optical can add costs. From a vertical perspective, education institutions, hotels, hospitals and large corporate campuses are all good candidates for POL. Even if building retrofitting isn’t an option, intra-building and broad campus use cases for POL are compelling. Customers from various industries value different merits from POL. For instance, on university campuses, there challenging environments, including dormitories, offices, libraries, canteens and labs. With POL, all services can be bundled into one. In hospitality, cable television can be carried as well as data and phone services. POL is efficient in space and energy usage, making it attractive to large campuses and buildings.

Companies should investigate POL as an alternative to traditional designs as a way to introduce long term savings for increasing bandwidth needs, greater operational efficiencies, and lower operating costs. They should not, however, use any POL system that isn’t managed with the same tools that their primary network is managed with.