What are network cabling options-optical fiber or copper cable?

A few years ago, people thought that the unshielded twisted pair copper cable had reached its limit in the fifth category of MHz. Many users and manufacturers turned their attention to the optical fiber and thought that the optical fiber is an inevitable transitional path for IT facilities. The optical fiber solves the disadvantages of unshielded twisted pair wires in various aspects: it has higher bandwidth, longer distance, higher security, completely eliminates RFI and EMI, and allows closer access to power cables, it does not pose a radiation threat to personal health.

Although optical fiber has inherent superiority over copper cables, we are still eager to find copper and connector manufacturers and try to extract the maximum speed from copper cables.

Why don't we abandon these efforts in copper instead of Installing Optical Fiber anywhere? A major factor involved here is the cost.

At a recent seminar, MOD-TAP chief executive Paul Andres predicted: "I believe that one day optical fiber will replace copper cable. I am talking about the entire system, including cables, installations, and active devices. The key issue is price differences. If the price of optical fiber cables is the same as that of copper cables, copper cables will be eliminated. This is similar to the elimination of four unshielded twisted pair wires when five types of cabling are reduced ."

How far is the day? Let's take a look at the current situation, the new measures taken by the wise installer, and the industry development trend, and then make some predictions based on this.

Current copper cable status

Most of the network cabling currently installed is unshielded twisted pair wires. The standards followed are generally the "cat5e" standards published by EIA/TIA and ISO. These performance standards meet the needs of ultra-high-speed network applications that are currently in the initial stage, such as Gigabit Ethernet and ATM systems with a rate higher than Gbps. These applications are designed to deliver information to the desktop at a rate above GB, compared with the common shared 10Base-T Ethernet system that most users are using, the rate of the former is about 100 to 1000 times that of the latter. Imagine that if the speed reaches 2000 Mbit/s, you can download the entire Mbit/s hard drive content from your PC within 16 seconds through the network. Therefore, copper cables are not useless in delivering "Urgent parcels" and will not be eliminated due to bandwidth restrictions.

Currently, wks that run at the highest rate through unshielded twisted pair wires are 2 to 4 Gbps ATMs. This kind of application is implemented through cat5e cabling. It adopts a perfect coding technology. The signal is transmitted separately through all four pairs of cables, and the speed of Gbps can be obtained at a frequency lower than MHz. The predefined cat6 cabling frequency limit is 200 MHz, and the future encoding system running at MHz will achieve a higher rate. Therefore, the data rate is not the deciding factor when we turn to the optical fiber.

Is the distance limit of unshielded twisted pair determined? At present, most office cabling requirements are generally less than the 100 m distance limit of copper cable, we seldom see that the cable distance required in office environments exceeds 100 m. However, as computer networks are used in more industrialized environments, such as warehouses, factories and petrochemical processing plants, distance restrictions will become an important issue.

At present, there are no EMI/RFI problems in most offices, the threat of industrial espionage is minimal, and no sensitive equipment is used. Therefore, the problem of copper emissions or radiation reception has little impact on most offices. Of course, people hope to solve this problem, but it is only hope.

In essence, optical fiber is superior to unshielded twisted pair wires in all aspects. However, these advantages are not critical to the daily problems of office networks, most organizations have difficulty accepting the huge cost difference between the two.

Cost Comparison between copper cable and optical fiber

Taking a typical office floor with 100 workstations as an example, we compare the cost of installing a 4-wire unshielded twisted pair cable channel with that of installing a Multimode Optical Fiber Channel. The unshielded twisted pair wires conform to cat5e Cabling Standards and are composed of cables, wiring boards, workstation sockets, and connectors at both ends of the channel. The Optical Fiber Channel consists of FDDI multi-mode optical fiber cables, wiring boards, workstation sockets, and connection wires at both ends.

1. Costs of unshielded twisted pair Structure

The following equipment must be installed: 1) 100 cat-5e unshielded twisted pair Cable data cables from the network cabling room to 100 user terminal stations; 2) RJ45 cat-5e wiring board, connect the unshielded twisted pair Cable End to the communication bracket; 3) horizontal cable management panel and vertical side ring to help support all RJ45 connectors between the hub and the wiring board; 4) use cat5e single-channel Surface Mounting blocks to connect each socket; 5) Cables with ethylene insulator labels attached to both ends of the cable, and the ethylene outlet labels printed by the machine attached to each socket Panel; 6) two-meter connection; 7) three-meter long cross-wiring; 8) cable bracket and suspension support system, supporting all unshielded twisted pair cables; 9) Record Book, record all plug-ins in the new Cabinet, and print the floor plan that has been built through the automatic CAD function of all installed sockets.

2. Cost of Fiber-to-desktop OFTD Structure

The following equipment must be installed: 1) 100 2-core multimode optical fiber cables from the communication local area network cabling room to 100 user terminal stations; 2) multimode SC Optical Fiber wiring board, connect the cable end to the communication bracket; 3) horizontal cable management panel and vertical side ring to support all duplex connectors; 4) use an optical fiber wallboard with a duplex coupler to connect each desktop; 5) package cables with ethylene insulator labels attached to both ends of the cable, while the machine prints the ethylene outlet labels, attached to each socket Panel; 6) two-meter-long duplex fiber SC connection; 7) duplex fiber user/desktop SC connection; 8) cable bracket and suspension Support System, provide support for all optical fiber cables; 9) record the records of all plug-ins in the new Cabinet, and print the existing floor plan through the automatic CAD function of all installed sockets.

Obviously, the cost of Fiber-to-desktop OFTD is much higher than that of unshielded twisted pair wires. Specifically, the cost of the former is more than three times that of the latter, and this is only the cost of passive parts in the network. If the cost of the source device is added, such as the hub and network interface card NIC), the cost difference will be further improved.

Copper, optical fiber, and wireless

In the past, in the horizontal channel connected to the workstation, we generally considered using "copper" or "Optical Fiber" as the selected transmission medium, and totally opposed the two. Let us jump out of the mindset that we must install the optical fiber system or the copper system in the horizontal channel. We need to install both the copper and the Optical Fiber System in the horizontal channel. By installing copper cables and optical fiber cables at the same time, users can spend less to get a better system, thus achieving innovation. For a few workstation or device in the farthest position, the distance may exceed the limit of 100, then the installer directly installs the optical fiber channel for these devices, instead of creating a separate wiring room. The cost of optical fiber cabling may be relatively high, but it can save a lot of cost because there is no need to install a wiring room or an active hardware.

The solution is not limited to optical fiber, but wireless equipment is also a medium worth considering because it has many advantages over copper and optical fiber, for example, in a historical classical building or constantly moving equipment, or in a warehouse. Each type of media has a corresponding purpose in the network. To provide cabling facilities with the highest cost-performance ratio, a comprehensive consideration must be taken.

From the perspective of experience, copper cable is the preferred medium in the office environment, because it has the lowest purchase cost, installation cost and maintenance cost. In the case of distance problems, optical fiber should be considered; in the case of access problems, wireless devices should be considered.

Let's take a look at the use of copper and optical fiber in the trunk. Currently, multi-mode optical fiber is installed in the trunk. To meet future bandwidth requirements, some contractors are installing a pair of single-mode optical fiber and hiding the single-mode optical fiber or no end-to-end connection. These single-mode optical fiber cables can be used when higher bandwidth is required one day in the future. The cost of one-time increase can be said to be minimal, but its long-term advantage is very obvious.

Development Trends in the cabling Industry

Cat6 specification is a hot topic for unshielded twisted pair wires. EIA/TIA and ISO standards organizations are working together to develop performance and testing standards for cat6 cabling, but there is still a long way to go before formal approval of the specifications.

On the other hand, the cost of optical fiber cabling is obviously decreasing. Both multimode fiber and single-mode fiber have high performance. Composite cables are being installed in many buildings, that is, multi-mode optical fiber and single-mode optical fiber. This represents a new development trend, different from the traditional development trend from multimode to single-mode.

The cost of the photoelectric device is too high. It is the obstacle of using single-mode optical fiber, especially the laser transmitter. However, some development work in the industry is making the cost of optoelectronic devices drop significantly. First, economies of scale. Due to the increasing use of laser, the cost is continuously decreasing. Currently, laser is most commonly used for Optical drives, including computers and audio devices. Secondly, the development of the new chipset significantly improves manufacturing costs. For example, Hewlett-Packard has released a VCSEL Vertical Cavity Surface Laser) chip, which is directly integrated with the laser transmitter, the cost is significantly different from that of traditional optoelectronic devices.

At the same time, the use of unshielded twisted pair wires and optical fiber cables can achieve higher performance, but there are also many problems, such as delay deviation, external NEXT, unshielded twisted pair cable wire diameter improvement; compact connectors, low laser costs, and increased demand for single-mode optical fiber cables.

Future Optical fiber channels

According to industry estimates, One day people will switch from unshielded twisted pair wires to optical fibers, but in the future we will see different optical fiber channels than the current OFTD.

In the future, the optical fiber channel will adopt a single-mode single-core optical fiber Bidirectional channel. Special Optical Fiber interfaces have already emerged on the market, allowing you to send and receive optical signals of different wavelengths at the same time. The transmitter sends an optical signal through a unidirectional reflector. The reflector is actually a piece of silicon, and it etching a very fine specific wavelength line on it. The signal is transmitted along the optical fiber through the reflector. When another reflector is encountered, the signal is reflected back and transmitted to the detector. At the same time, another signal sent by the transmitter can be sent to the detector at the other end. One optical fiber is connected to each workstation and one optical fiber is connected to each desktop. In this way, a single-mode single-core optical fiber can transmit signals simultaneously in two directions.

Single-mode single-core optical fiber channels reduce the cost of connectors and wiring boards by half each office with one connector), and the cost of the connection line is also reduced by half, because we can replace the duplex connection line with a single work line. Cable and wall panel costs are reduced. This model provides an alternative solution that costs less than the current five types of unshielded twisted pair wires. The only limiting factor that makes this solution cost unavailable is the source device. The real driving factor is that the network hub manufacturer will be able to accommodate twice the number of channels at the front end of the plug-in card. Some vendors say they can accommodate up to 100 channels on a card, but the limitations of the interconnection space make it unable to implement this method. Combining the single-core optical fiber model with the new compact Optical Fiber Connector can gradually solve space problems.

At present, multimode optical fiber is the main optical fiber medium in the structured cabling system, but Multimode Optical Fiber only accounts for 1% of the entire optical fiber industry. Communication operators do not use multimode optical fiber at all, nor do cable TV companies use Multimode Optical Fiber. They all use single-mode optical fiber. The only industry that uses multimode optical fiber cables is the data industry. According to the standards provided by the new specification, the maximum cabling distance of multi-mode optical fiber cables is 300 meters, rather than the previously called 2000 meters. The purpose of limiting the distance to 300 is to completely implement Protocol Transition, but it also brings problems to multimode optical fibers. Single-Mode Optical Fiber solves this dilemma. Single-Mode Optical Fiber is an excellent technology that can provide much higher bandwidth and distance, lower manufacturing costs, and greatly improve the connector technology, you can now easily install a single-mode connector just like installing a multi-mode connector.

The cost difference between single-mode fiber and multi-mode fiber is very high, but as the connector price drops and the termination method is simplified, single-mode fiber will become a more attractive option.

Generally, the rated rate of multimode optical fiber is 500 Mbps per kilometer, and the rate of horizontal wiring is 5 Gbps per 100 meters. Multi-mode optical fiber is a product with an inverse length and bandwidth. The longer the distance, the slower the data rate. Therefore, to support the 300 Gbps asynchronous transmission mode on the trunk, the maximum distance is only meters. The problem with multimode optical fiber is that the data rate is constantly increasing, but the specification of the optical fiber cable remains unchanged. Therefore, if the distance is too long, the bandwidth of the multi-mode trunk cable in the complex environment may not be higher than that of the 622Mbps asynchronous transmission mode. On the contrary, carriers currently use single-mode optical fiber cables and use OC192 protocol to run at a rate of 160 Gbps. Many laboratories are experimenting with Dense Wavelength multiplexing (DWDM) technology. In this technique, optical fiber can transmit light of different wavelengths at an interval of only 0.8 microns. This is a broadband system similar to a cable TV system. Many laboratory systems can run 150 channels at the same time, and the bandwidth of each channel is 10 Gbps. That is to say, the bandwidth of the optical fiber can reach 1.5 bits per second (Tb, 1 Tb = 1000 Gb ). Theoretically, the bandwidth of a single-mode optical fiber can reach 25 bytes per second.