Corporate data networks have become a basic infrastructure within the business environment gaining more importance the larger the company to increasing the number of employees who require connectivity, both among themselves and with the outside. These networks, in addition provide service to work stations have other functions, such as connecting the video surveillance systems with the security server, IP phones to the telephone exchange or provide the audio and video conferencing rooms an adequate bandwidth for proper operation.

The decision on the technology used in the design of these networks is something that should be treated carefully: not only have a direct impact on the cost of installation, but also the cost of annual maintenance and even for future scalability to accommodate new users and services.

Currently, the deployment of networks in corporate buildings is done with Ethernet cable and technology. For years this has been the solution, offering speeds of 10/100/1000 Mbps per user. The topology used is typically the "star": one or more switches per plant, to which are connected one by one all the network points. Between each switch is set an optical fiber of more capacity, creating a backbone or transport network. 

The star topology is inefficient in cable and space: from each switch comes out an Ethernet cable for each point of the network. In addition, it is common to have several parallel networks (comprising servers, cables, switches, etc.), data networking, telephony (traditional or IP) or video surveillance system and security. The reason for this redundancy is usually that each network requires a level of minimum quality of service that can not be guaranteed while sharing the physical transmission medium. 

In turn, each of the switches needs a refrigerated location and a power supply to operate, so it is often conditioned a network cabinet or room on each floor. The star topology involves large amounts of cable to reach the network points, always starting from network hubs: overall installation/extension of an Ethernet network becomes slow and expensive. Moreover, due to the nature of their media access technology, switching and network autoconfiguration do not help the detection, location and resolution of incidents (e.g. physical, defective switch or network loops). Finally it is noteworthy that the maximum distance of a copper cable between a point the network and the switch, or between two switches, is 100m, thus, in many cases, the fiber ends up being present in the Ethernet deployments.

The FTTD solution (Fiber To The Desk)

The solution Fiber-To-The-Desk or FTTD is a different approach to the installation of a corporate network GPON and point-multipoint topology, tree-like, to perform the deployment. The use of fiber optics and a tree-shaped topology solves the disadvantages described above.

A FTTD network is based on the deployment of a GPON that from an OLT will distribute and divide an optical fiber down to each of the ONTs located in desks, offices or facilities of the company. Each ONT has 2 phone ports and 4 Ethernet ports for connecting as many devices, such us workstations, security cameras, IP phones, projectors, video conferencing stations, etc. The OLT of the central consists of different service cards with multiple ports GPON for each, being able to create a GPON network from each port. 

The way that reaches the optical fiber to each of the 64 ONTs that can connect to the GPON is through a tree-topology, by dividing the signal with passive optical couplers/splitters, so not requiring power. Regarding the distance, GPON is designed to cover up to 20Kms, which allows covering with the same optical network campus-like environments with multiple buildings and corporate offices. Moreover, this distance can be increased with the use of GPON range extenders, allowing distances of up to 60 km and 128 users per PON, in case of need to cover a wider area without degrading the bandwidth offered -2,5Gbps at 1.25 Gbps in downstream and upstream-, with the distance.

Another advantage offered by solutions of fiber to the desktop (FTTD) is a major cost savings in both installation and maintenance. Installation is easier while having to deploy far fewer cables (one fiber per PON at the OLT unlike one per user in Ethernet switches) and smaller in size to each workstation, keeping also in mind that the optical fiber is cheaper the Ethernet cable. (High cost of copper versus fiber glass).

By using only passive elements for the deployment also makes it unnecessary to reserve rooms, cabinets or network equipment on each floor, eliminating the need for power, ventilation, etc. involved in the case of an Ethernet solution. To energy savings that this implies it must be added the reduction in consumption per port, as each Ethernet port consumes an average of 3W of power while one optical connection consumes only between 1W and 1.5 W. In the case of a company with 500 employees in which each of them using a workstation and an IP phone, for example, we're talking a saving of between 750W and 1000W only in network interfaces that must be added to the cooling equipment itself. 

Maintenance costs are also lower as it moves from managing a main switch, plus at least one per floor, to manage only the OLT and through it the ONTs, users and network services of the corporate GPON. These maintenance costs are also cheaper by the durability of the equipment, since the Ethernet switches typically have a lifespan of 5 to 7 years while the optical equipment last longer than 10. Also, the network upgrade is much easier, since it is not necessary to change the fiber optic cable to get higher speeds in the future as in the case of Ethernet cable.

Of course, the main feature of the fiber optic network over the Ethernet network is the higher bandwidth offered per connection point. Accompanied by a capacity management of complete Quality of Service (QoS) associated with the different services transported. In traditional Ethernet networks, tended to assure QoS by network dimensioning. Overall the PON end up carrying more traffic, more efficiently.

The capacity of users with current GPON networks is 64 users per PON, while the central equipment may have different PON card and new cards can be added to further expand the number of users and network access available. This gives an idea of how scalable is this type of optical networks. 

Telnet-RI products for FTTD solutions

Telnet has an OLT solution consisting of a high performance chassis for up to 14 GPON cards. Each OLT card has 4 GPON ports. This makes it possible to service 256 ONTs per card and 3584 per OLT. 

In addition, Telnet has GPON ONTs with 4 Ethernet ports, which enables each OLT card to have 1024 users or computers connected to and up to 17,920 if the full capacity of the chassis. This gives an idea of the network scalability of the Telnet FTTD solution and the amount of cable needed to reach the same capacity in a conventional Ethernet network. 

In addition to the Ethernet ports, it also has 2 POT connection ports, making it also suitable for companies that do not have an IP telephony system. This will replace both the Ethernet cabling and the telephone pair by a single fiber optic cable, reducing the size required in ducts and facilitating the maintenance of the network.

As mentioned above, it is possible to extend both the distance and the number of ONTs of a PON network using active elements called GPON range extenders. GPON-Extender is the family of Telnet for such applications. This equipment is capable of regenerating the optical signal and return it through a port (in the case of GPON-Extender 1:1) or 4 ports simultaneously (GPON-Extender 1:4), thus saving a level of optical division.

Telnet also has full range of passive optical components of a GPON network, from the couplers/dividers that create the different branches of the GPON network to the distribution boxes in plants or in buildings the case of networks such as campus as well as optical wall sockets and connectors. These items would replace the plant switches, giving an idea of cost savings, space and maintenance accomplished with a passive optical network.

As manufacturer of cable, Telnet also commercializes all kinds of cable that can be used in such deployments. Raiser cable, horizontal drop cable, patch cords, pigtails...  

For indoors the low radius of curvature cables are especially interesting, as they are able to adapt more flexibly to corners and angles without compromising the quality of the connection. Besides this, all internal cables pass the strictest tests of low smoke and zero halogen. 

Telnet also manufactures exterior laying cable, whether self-supported, or underground in the case of having to cover different buildings. All our cables have passed the strictest test of endurance and quality, as well as different types of optical fiber used in their manufacture