Kevin LENGLE, Ph.D, Product Line Manager AROONA, Cailabs, discusses why a disruptive technology approach to multi-mode fibre is of great benefit for campuses as it now enables the gradual and flexible evolution of the local network’s optical infrastructure without the operational and cost constraints of cable deployment.
Digital communication has exploded in recent years and now plays a major role in campuses. This change in communication method has a direct impact on the underlying cabling infrastructure. In order to facilitate this expansion and avoid congestion problems, local networks need to constantly improve their performance.
In this article, we dispel some myths about the capacity limitations of multi-mode fibre which makes up most campus backbones. We will present a disruptive technology approach to increase the bandwidth of existing multi-mode networks, allowing them to be upgraded in a practical, cost-effective and environmentally friendly way while meeting the current and future needs of LANs. Let’s take a closer look at this new trend.
A growing demand for increased bandwidth in local networks
Within local networks, a growing number of applications require considerable bandwidth to ensure the transfer of large volumes of data and streaming of audio and video files. In addition to the various business applications specific to each campus, the increasing use of mobile terminals and smart devices has contributed to the growth in bandwidth requirements, in particular with the latest Wi-Fi 6 and 5G standards. Bandwidth-intensive applications and latency-sensitive traffic can be found everywhere in local area networks. Network managers need to be able to transmit these data streams reliably and with a high-quality of service.
It should be noted that the majority of inter-building cable networks within campuses is made up of multi-mode fibre. However, multi-mode fibre inherently has limited bandwidth and cannot support throughputs of 10 Gb/s or more currently required by campus-wide links (due to modal dispersion limitation). This especially applies to first-generation OM1 and OM2 multi-mode fibres, on which a 10 Gb/s throughput can only travel up to 33 m and 80 m respectively. Next-generation single-mode fibres do not have this capacity limitation problem. So, is it possible to magically transform old multi-mode fibres into single-mode fibres to meet the growing demand for bandwidth in local networks? You may be surprised to know that the answer is yes!
The conventional solution has been to replace the old cabling with next-generation fibre. However, redeploying fibre cable is often a difficult task that has significant impact on business activities. In some cases, micro-trenches or more invasive work in general, may be required to install the new cables throughout the campus. Replacing cables can therefore require tedious installation work with complex project management and exorbitant costs, which has a significant impact on business operations. However, rip and replace is not necessarily the only solution. Optical technologies have evolved and there is now a disruptive alternative to complex fibre network deployments.
A disruptive approach beyond the standards
The problem of MMF transmission capacity was discussed a few years ago within the IEEE workgroups. Designed for backward compatibility with OM1 and OM2 fibres, a type of 10 Gb/s interface was developed within the IEEE 802.3aq standard, referred to as long reach multi-mode (LRM). By combining signal processing to compensate for modal dispersion with specific MMF beam injection conditions using mode conditioning patchcords, it is possible to achieve a range of about 200 m at 10 Gb/s. However, this does not cover all the current needs of local networks in terms of throughput and reach.
Fortunately, optical technologies have evolved in recent years and it is now possible to use innovative beam shaping solutions to address this issue. This article will not provide a detailed physics course on modal shaping, rather the aim here is to focus on the value proposition and opportunities for IT managers. The recent introduction of simple off-the-shelf devices means that the speed and distance limitations of multi-mode fibre can be overcome and throughputs of up to 100 Gb/s can now be carried over existing legacy multimode infrastructure for up to several kilometres.
Regardless of the business sector, network managers need to upgrade their existing networks to meet future needs and are constantly looking for ways to improve the efficiency of their infrastructure while optimising capital and operating expenditure. This disruptive technology approach is of great benefit for campuses as it now enables the gradual and flexible evolution of the local network’s optical infrastructure. These solutions are interoperable and compatible with any type of multi-mode fibre (OM1 to OM5, i.e. 62.5/125 µm or 50/125 µm), thus helping to preserve existing network infrastructure. These innovative solutions are passive (i.e. no power consumption, configuration, or monitoring required) and transparent to the communication protocol and modulation format used. Technically, this provides an opportunity for network managers to implement single-mode wavelength division multi-plexing (WDM) technologies on MMF where necessary, to perform single-mode/multi-mode media conversion functions passively, or to deploy GPON within a Passive Optical LAN architecture on MMF. These applications would not have been possible before the development of these disruptive technologies.
Rip and replace is not necessarily the best option. This new technological approach has already proven its effectiveness across numerous industrial, military, university and hospital campuses around the world. As a valid alternative to complex recabling, these technological innovations make it possible to solve the campus network bandwidth problem in a practical, economical and environmentally friendly way, with proven benefits for end-customers and ICT professionals alike.
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