Wiring choose fiber optic cable or copper cable


A few years ago, people thought that the unshielded twisted pair copper cable had reached its limit at 100MHz of Category 5. Many users and manufacturers turned their attention to optical fiber, thinking that optical fiber was an inevitable transition path for IT facilities. Optical fiber solves the disadvantages of unshielded twisted pair in all aspects: it has higher bandwidth, allows longer distances, is more secure, completely eliminates RFI and EMI, allows closer proximity to power cables, and is not harmful to human health pose a radiation threat.


Despite the inherent advantages of fiber over copper, we are now enthusiastically looking for copper and connector manufacturers, striving to extract the ultimate speed from copper.


Why don't we just install fiber everywhere and forgo these efforts in copper? A major factor involved here is cost.


At a recent seminar, Paul Andres, CEO of MOD-TAP, predicted: "I believe that one day fiber will replace copper. I'm talking about the entire system, including cables, installations and active equipment. The key issue is the price difference. If fiber is the same price as copper, then copper will be obsolete. This is very similar to when Category 5 cabling prices fell, Category 4 unshielded twisted pair was eliminated.”


So how far is it from that day? Let's take a look at the current situation, new steps taken by smart installers and trends in the industry, and then make some predictions based on that.


Current Status of Copper Cables

Most of the network cabling currently installed is unshielded twisted pair, and the standards it follows are generally the "category fivee" standards published by EIA/TIA and ISO. These performance standards meet the needs of ultra-high-speed network applications that are still in their infancy, such as Gigabit Ethernet and ATM systems with rates higher than 1.2 Gbps.


These applications are designed to deliver information to the desktop at rates above gigabits, which is about 100 to 1000 times faster than the common shared 10Base-T Ethernet systems most users are using . Imagine if the rate hit gigabits per second, you could download the entire 2000 megabytes of hard drive content in a PC over the network in 16 seconds. Therefore, copper cables are not useless when transmitting "urgents", nor will they be eliminated due to bandwidth limitations.

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Currently, the highest rate workstation application marked for operation over unshielded twisted pair is ATM at 2.4Gbps. This application is achieved through Category 5e cabling, which uses a well-established encoding technique, and the signal is transmitted separately through all 4 pairs of wires in the cable, which can achieve a rate of 2.4Gbps at operating frequencies below 100MHz. The predetermined frequency limit for Category 6 wiring is 200MHz, and future coding systems operating at 200MHz will achieve higher rates. So data rates are not the deciding factor when we move to fiber.


So is the distance limit of unshielded twisted pair the deciding factor? Currently, the wiring length required in most offices is generally lower than the 100-meter distance limit of copper cables, and we rarely see cable distances that exceed the required distance in office environments. 100 metres. However, as computer networks are used in more industrialized environments, such as warehouses, factories and petrochemical processing plants, distance constraints will become an important issue.


Currently, there are no EMI/RFI issues in most offices, the threat of industrial espionage is minimal, and no sensitive equipment is used. Therefore, the issue of copper cables emitting or receiving radiation has little effect in most offices. Of course, people hope to solve this problem, but only hope.


Fiber is inherently superior in every way to unshielded twisted pair, but these advantages are not very critical to the day-to-day problems of office networks, and as a result, the vast cost difference between the two is difficult for most organizations to accept .


Cost Comparison of Copper and Fiber

Let's compare the cost of installing a 4-pair unshielded twisted pair channel versus installing a multimode fiber channel using a typical office floor containing 100 workstations as an example. The unshielded twisted pair channel conforms to the Category 5e wiring standard and consists of cables, patch panels, workstation sockets and patch cords at both ends of the channel. Fibre Channel consists of FDDI grade multimode fiber optic cables, patch panels, workstation sockets, and patch cords at both ends.


1. Cost of unshielded twisted pair structure

The following equipment needs to be installed: (1) 100 unshielded twisted pair data cables from the network wiring room to 100 user terminal stations; Attached to the communication bracket; (3) Horizontal cable management panel and vertical side ring in the communication bracket to help support all RJ45 patch cords between the hub and patch panel; (4) Use Category 5e single channel surface mount block end connected to each socket; (5) cable labels covered with vinyl insulation, affixed to both ends of the cable, and machine-printed vinyl socket labels, affixed to each socket panel; (6) two-meter patch cords; ( 7) Three meters of jumper wires; (8) Cable tray and hanging wire support system to provide support for all unshielded twisted pair cables; (9) Logbook to record all patching conditions in the new cabinet and pass all Automatic CAD function of installed sockets to print out the built floor plan.


2. The cost of fiber to the desktop (OFTD) structure

The following equipment needs to be installed: (1) 100 2-core multimode optical cables from the communication local area network wiring room to 100 user terminal stations; (2) multimode SC optical fiber patch panels to terminate the cables on the communication brackets; (3) ) Horizontal cable management panels and vertical side rings to help support all duplex patch cords; (4) Terminate each tabletop with fiber optic wallplates equipped with a duplex coupler; (5) Cable labels wrapped with vinyl insulation , affixed to both ends of the cable, and machine-printed vinyl receptacle labels, affixed to each receptacle panel; (6) two-meter duplex fiber optic SC patch cords; (7) duplex fiber optic user/desktop SC jumpers ; (8) Cable tray and hanging wire support system to provide support for all optical fibers; (9) Log book to record all connections in the new cabinet and print out the built Floor plan.


Obviously, the cost of fiber to the desktop (OFTD) is much higher than the cost of unshielded twisted pair. To be precise, the cost of the former is more than three times that of the latter, and this is only the cost of passive components in the network. When you add the cost of active devices, such as hubs and network interface cards (NICs), the cost difference increases even further.


Combination of copper, fiber, and wireless

In the past, in the horizontal channel connecting workstations, we generally considered using "copper cable" or "optical fiber" as the transmission medium of choice, and completely opposed the two. Let's get out of the mindset of having to install either a fiber optic system or a copper cable system in the horizontal channel, we need to install both copper and fiber optic systems in the horizontal channel. By installing copper and fiber at the same time, users can get a better system at a lower cost, enabling innovation.


For the few workstations or devices at the furthest locations that may exceed the 100-meter limit, the installer will install Fibre Channel directly for these devices instead of building a separate wiring closet. Fiber optic cabling can be expensive, but can save a lot of money by not having to install a wiring closet and active hardware.


Workarounds are not limited to fiber optics, wireless is also a medium worth considering as it has many advantages over copper and fiber, such as in historic legacy buildings or in constantly moving equipment, such as in warehouses middle. Each medium has a corresponding use in the network, and in order to provide the most cost-effective cabling facility, it must be considered comprehensively.


As a rule of thumb, copper cable is the medium of choice for the office environment because it has the lowest purchase cost, installation cost, and maintenance cost. When there is a distance problem, the use of optical fiber should be considered; when there is an access problem, the use of wireless equipment should be considered.


Let's take another look at the use of both copper and fiber in the backbone. Currently, we install multimode fiber in the backbone. To meet future bandwidth requirements, some contractors are installing a pair of single-mode fibers that are hidden or unterminated. These single-mode fibers can be used when higher bandwidth is required someday in the future. The one-time incremental cost is minimal, but the long-term benefits are clear.


Development trend of wiring industry

The Category 6 specification is a hot topic for unshielded twisted pair cables. EIA/TIA and ISO standards bodies are working together to develop performance and test standards for Category 6 cabling, but a formally approved specification is still a long way off.


On the other hand, the cost of fiber optic cabling is dropping significantly. Both multimode fiber and single mode fiber have high performance levels. Composite cables are now being installed in many buildings, using both multimode fiber and single mode fiber. This represents a new development trend, which is different from the traditional development trend from multi-mode to single-mode.


The high cost of optoelectronic devices has been an obstacle to the adoption of single-mode fibers, especially laser transmitters. However, some development work in the industry is bringing the price of optoelectronic devices down significantly. The first is economies of scale. As the use of lasers continues to rise, their costs continue to decline. Currently, the most common use of lasers is for optical drives, including computers and audio equipment. Secondly, the development of new chip sets has significantly improved the manufacturing cost. For example, Hewlett-Packard has released a VCSEL (Vertical Cavity Surface Emitting Laser) chip, which directly integrates the laser emitter, which is significantly different from the cost of traditional optoelectronic devices. difference.


Higher performance can be achieved by using both UTP and fiber optics, but there are also many issues such as delay skew, external NEXT, increased UTP cable conductor diameter; compact connectors, low laser cost, single-to-single The demand for mode fiber optic cables increases and so on.


Fibre Channel of the Future

The industry predicts that someday people will move from unshielded twisted pair to fiber, but the fiber channel we will see in the future will not be the same as today's OFTD.


The future Fibre Channel will be a bidirectional channel using single-mode single-core fiber. Special optical fiber interfaces have begun to appear on the market, which can simultaneously send and receive optical signals of different wavelengths. The transmitter sends the light signal through a one-way reflector, which is actually a piece of silicon with ultra-fine lines of specific wavelengths etched into it. The signal travels along the fiber through the reflector, encounters another reflector, reflects back, and transmits it to the detector. At the same time, another signal from the transmitter can be sent to the detector at the other end. One fiber is connected to each workstation, and one fiber is connected to each desktop, so that a single-mode single-core fiber can transmit signals in both directions at the same time.


Single-mode single-core Fibre Channel cuts the cost of connectors and patch panels in half (one connector per office) and half the cost of patch cords because we can replace duplex patch cords with simplex patch cords. Plug in. Cable costs go down, wall panel costs go down. This model provides an alternative costing less than current Category 5 unshielded twisted pair. The only limiting factor that makes this solution cost-effective is the active device. The real driver now is that hub manufacturers will be able to accommodate twice as many channels on the front of the patch card. Some vendors say they can fit up to 100 channels on a single card, but interconnect space constraints prevent this approach. Combining the single-core fiber model with the new compact fiber connector can gradually solve the space problem.


At present, multimode fiber is the main fiber medium in structured cabling systems, but multimode fiber accounts for only 1% of the entire fiber industry. Telecom operators will not use multi-mode fiber at all, and cable companies will not use multi-mode fiber. They all use single-mode fiber. The only industry that uses multimode fiber optic cables is the data industry. According to the standard provided by the new specification, the maximum cabling distance of multimode fiber is 300 meters, not 2000 meters as previously called. The purpose of limiting the distance to 300 meters is to fully implement the protocol transition, but it also creates problems for multimode fiber. Single-mode fiber solves this dilemma. Single-mode fiber is an excellent technology that offers much higher bandwidth and distance, lower manufacturing costs, and connector technology has improved so much that users can now install as easily as multimode connectors Single mode connector.


The cost difference between singlemode fiber and multimode fiber is high, but as connector prices drop and termination methods simplify, singlemode fiber will become a more attractive option.


In general, multimode fiber is rated at 500 Mbps per kilometer and 5 Gbps per 100 meters in horizontal cabling. Multimode fiber is a product whose length and bandwidth are inversely proportional, the greater the distance, the slower the data rate. Therefore, to support 1.2Gbps Asynchronous Transfer Mode on the backbone, the maximum distance is only 300 meters. The problem with multimode fiber is that data rates keep increasing while the specifications for fiber optic cables don't change. Therefore, if the distance is too far, the bandwidth of the multimode trunk cable in the building environment may not be much higher than the 622Mbps asynchronous transfer mode. On the contrary, operators currently use single-mode fiber and through the OC192 protocol, the user's operating rate has reached 160Gbps.


Many laboratories are experimenting with dense wavelength division multiplexing (DWDM) technology. In this technique, different wavelengths of light can be transmitted through an optical fiber at intervals of only 0.8 nanometers. This is a broadband system similar to a cable TV system, many laboratory systems can operate 150 channels simultaneously, each channel has a bandwidth of 10Gbps, that is, the bandwidth of the fiber can reach 1.5 terabits per second (Tb, 1Tb =1000Gb). In theory, the bandwidth of single-mode fiber can reach 25 terabits per second.



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