Månadsvis arkiv: June 2016

Learning Five Ways to Test Fiber Optic Cables

In this technological world filled by fiber optic systems everywhere, one won’t fail to enjoy the benefits brought by fiber optics in daily life. In a whole fiber optic system, the most essential part should be the fiber optic cable. This cable is made up of incredibly thin strands of glass or plastic capped with the same (eg. ST ST fiber cable) or different connector types (LC ST patch cable) on the ends, used as the medium to carry information from one point to another with light-based technology. Just like electricity that can power many types of machines, beams of light can carry many types of information, so fiber optics do great to people in many ways, like broadcasting, transportation, medicine, etc..Along with the heavy use of fiber optic cables, testing the installed cables also gains importance in practical use. Since there are many standards available for testing, some people may get confused. But don’t worry. This text is written with an attempt to clear off this confusion.

Testing Principles

Generally speaking, five ways are listed in various international standards from the EIA/TIA and ISO/IEC to test installed cable plants. First three of them use test sources and power meters to make the measurement, while the last two use an optical time domain reflectometer (OTDR). Let’s first see the different results from these methods, and then delve into each one.

different testing results from power/meter source and OTDR

The use of source and power meter method, also known as “insertion loss”, simulates the way the actual network uses the cable plant. The test source mimics the transmitter, and the power meter the receiver. But insertion loss testing requires reference cables attached to the source and meter to connect to the cable under test. This insertion loss test can use 1, 2 or 3 reference cables to set the “zero dB loss” reference for testing. Each way of setting the reference gives a different loss. While OTDR is an indirect method, using backscattered light to imply the loss in the cable plant, which can have large deviations from insertion loss tests. OTDRs are more often used to verify splice loss or find damage to cables.

Source/Power Meter Method

In source and power meter method, all the three tests share the same setup (shown below), but the reference power can be set with one, two or three cables as explained next. In general, the 1 reference cable loss method is preferred, but it requires that the test equipment uses the same fiber optic connector types as the cables under test. If the cable (ST ST fiber cable) has different connectors from the test equipment (SC-SC on the tester), it may be necessary to use a 2 or 3 cable reference, which will give a lower loss since connector loss is included in the reference and will be subtracted from the total loss measurement.

the same setup of power/meter source method (1/2/3 cable references)

  • Reference per TIA OFSTP-14 (1 Cable Reference)

This method, formerly called method B, uses only one reference cable. The meter, which has a large area detector that measures all the light coming out of the fiber, effectively has no loss, and therefore measures the total light coming out of the launch reference cable. When the cable is tested as below, the measured loss will include the loss of the reference cable connection to the cable plant under test, the loss of the fiber and all the connections and splices in the cable plant and the loss of the connection to the reference cable attached to the meter.

  • Reference per TIA OFSTP-14 (2 Cable Reference)

This one, formerly called method A, uses two reference cables with one launch cable attached to the source, and the other receive one attached to the meter. (The two cables are mated to set the reference.) Setting the reference this way includes one connection loss (the mating of the two reference cables) in the reference value. When one separates the reference cables and attaches them to the cable under test, the dB loss measured will be less by the connection loss included in the reference setting step. This method gives a loss that’s less than the 1 cable reference.

  • Reference per TIA OFSTP-14 (3 Cable Reference)

Reference cables are often patch cords with plugs, while the cable under test has jacks on either end. The only way to get a valid reference is to use a short and good cable as a “stand-in” for the cable to be tested to set the reference. To test a cable, replace the reference cable with the cable to test and make a relative measurement. Obviously this method includes two connection losses in setting the reference, so the measured loss will be less by the two connection losses and have greater uncertainty. Finally, here goes the picture showing the testing case with one, two, three reference cables.

testing case with one, two, three reference cables

OTDR Testing

With only one lunch cable, the OTDR can measure the length of the cable under test and the loss of the connection to the cable under test plus the loss of the fiber in the cable under test, and any other connections or splices in the cable under test. However, this method doesn’t test the connector on the far end of the cable under test, because it isn’t connected to another connector, and connection to a reference connector is necessary to make a connection loss measurement.

OTDR testing method

If a receive cable is used on the far end of the cable under test, the OTDR can measure the loss of both connectors on the cable under test as well as the fiber in the cable, and any other connections or splices in the cable under test. The placement of the B marker after the connection to the receive cable means some of the fiber in the receive cable will be included in the loss measured.


Hope this article is helpful for you to understand various methods existing to test fiber optic cables. For more information about testing methods or testing tools, you can directly connect me at Linkedin@Fern Xu (Fiberstore).

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Introduction to 40G QSFP+ Cabling Assemblies

Today’s high-performance computing environments featuring by switching and routing, cloud computing and virtualization require higher network speeds, greater scalability, and higher levels of performance and reliability in data centers. Some bandwidth-hungry applications, like video streaming applications, also drive data rates to higher points. These all boost the need for a migration to 40G and 100G interfaces as 1 and 10G can’t meet the bandwidth needs well. 40G interface is QSFP (Quad Small Form-factor Pluggable) which has several standards requiring different connectors to fit cabling infrastructure, so as to achieve network connectivity. Do you know what cabling infrastructure is needed to support 40G applications? MPO/MTP cable, direct attach cable (DAC), or LC fiber patch cable? Have any ideas? Follow this article and find the answer.


MTP is a registered trademark of US Conec used to describe the connector, and MPO stands for multi-fiber push-on or also multi-path push-on. Actually, the former product is 100% compatible with the latter. Thus, only MTP is written for simplicity in the following paragraphs. In 2010, the IEEE 802.3ba standard specifies MTP connectors for standard-length multi-mode fiber (MMF) connectivity. Its small, high-density form factor makes MTP cable ideal for higher-speed 40G networks in data centers.


To support 40G applications, a 12-fiber MPO connector is needed. The typical implementations of MTP plug-and-play systems split a 12-fiber trunk into six channels that run up to 10 Gigabit Ethernet (depending on the length of the cable). 40G system uses 12-fiber trunk to create a Tx/Rx link, dedicating 4 fibers for 10G each of upstream transmit, and 4 fibers for 10G each of downstream receive, leaving the middle 4 fibers unused. The upgrade path for this type of system entails simply replacing the cassette with an MTP-to-MTP adapter module.

Direct Attach Cable

Besides MTP cable, many data centers also like to choose DACs for 40G cabling infrastructure. DAC, a kind of optical transceiver assembly, is a form of high speed cable with “transceivers” on either end used to connect switches to routers or servers. The “transceivers” on both ends of DACs are not real optics and their components are without optical lasers, thus DACs are much cheaper, preferable for 40G data center applications. As such, the fiber connectivity cost is significantly reduced by using either direct attach copper cables or active optical cables (AOCs) instead of costly fiber transceivers and optical cables.

  • Direct Attach Copper Cable

Direct attach copper cables are designed in either active or passive versions for short-reaches in data center. Compared with active optical cables, these copper cables are less expensive. Nowadays, there are many twinaxial cables available to support 40G (10G x four channels), in QSFP+ to QSFP+ (ie. EX-QSFP-40GE-DAC-50CM) version or in QSFP to 4 SFP+ cable assembly (eg. QSFP-4SFP10G-CU5M).

40g qsfp-qsfp dac vs. qsfp- 4 sfp+ dac

The issue is that copper cable is stiff and bulky, thus consuming precious rack space and blocking critical airflow. But with the advancing technology, manufactures produce a thinner, uniquely shielded ribbon-style twinaxial cable that can support speeds of 10G per channel while addressing many of the concerns associated with round, bundled cable. And the ribbon-style twinaxial cable is significantly slimmer than its round counterparts. Even better, the cable can be folded multiple times and still maintain signal integrity, allowing for higher density racks and space savings.

  • Active Optical Cable

Being a form of DAC, AOC integrates single-mode fiber (SMF) or MMF cable terminated with a connector and embedded with transceivers. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable. AOCs can reach a longer distance copper cables, and use the same interfaces as copper cables, typically used in data center. Similar to direct attach copper cables, AOCs are also available in QSFP+ to QSFP+ (eg. QSFP-4X10G-AOC20M) and QSFP+ to 4 SFP+ cabling (ie. QSFP-4X10G-AOC10M) versions.

qsfp-qsfp aoc vs. qsfp-4-sfp+ aoc

Since 40G AOC connectors are factory pre-terminated, 40G AOC is easier for installation and thus less affected by the repeating plug during daily use than MTP cable. In case there was a fault in the interconnection, for AOC, you can just replace it with another AOC.

LC Fiber Cable

Certainly, LC fiber cable can also be the cabling solution for the long-reach 40G QSFP+ modules (40GBASE-LR4). That is, 40GBASE-LR4 QSFP+ uses a duplex LC connector as the optical interface, able to support transmission distance up to 10km over single-mode fiber (SMF).


40G cabling assemblies, including MTP cable, DAC, AOCs, and LC fiber cable, permit multiple connectivity options in data centers. While for some companies, the main issues facing them are the the low-quality and incompatible products. If you choose Fiberstore for product, then such quality and compatibility problems can be avoided. Besides, its 40G cables are test-assured to be compatible with major brands, provided at really low prices. You can visit Fiberstore for 40G cables to achieve 40Gbit/s links.

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Information About Fiber Optics History & Advantages

It’s well known that the simplest form of fiber optics is a medium which is taken to carry signals from one point to another in the form of light. It’s composed of a transmitting device, which sends the light signal, fiber optic cables that serve as a conduit for pulses of light to travel over distances, and a receiver, which accepts the light signal transmitted. It often occurs that fiber systems are often be used as the alternative solutions to traditional copper-based communications systems, since fiber optic cables outweigh copper cables in less signal loss and immunity to electromagnetic interference (EMI). Certainy, the advantages of fiber optics are not limitted to the mentioned two sapects. Following passages will discuss more virtual points of fiber optics, coupled with its history.

Fiber Optics: History

In 1880, the photophone was invented, a great inventory used to speak into a microphone which would then cause a mirror to vibrate. The sun’s light would strike the mirror, and the vibration of the mirror would transmit light across an open distance of about 656ft (200m). The receiver’s mirror would receive the light and cause a selenium crystal to vibrate, causing the noise to come out on the other end. Although the photophone was successful in allowing conversation over an open space, it had a few drawbacks: it did not work at night, in the rain or if someone walked between the signal and receiver. Then this idea was given up.

200m reach with the sun light

In 1950s, the laser was invented. This device was a finely controlled beam of light that could transmit information over long distances. Unfortunately, the same drawbacks also plagued the laser. Although it could be used at night, it did not work during rain, fog or at any time when a building was erected between the sender and the receiver.

Scientists at Corning developed the first practical fiber optic cables in the 1970s, based on the idea of “total internal reflection”. This is the principle that fiber cables are built upon, and it basically means that an optical fiber consists of a core of transparent glass, surrounded by outer layer, (called “cladding”) of slightly less transparent glass which reflects the light back into the core.

What Makes Fiber Optics Special?

What is special about fiber optics? As mentioned above, fiber optic cables are made out of glass, and carry pulses of light energy. The idea of a flexible piece of glass sounds a bit counter-intuitive, but in some ways, fiber optic cables are stronger and more durable than copper cables.

Nowadays, fiber optic cables are used for many different telecommunication applications, like data centers, data warehouses, server farms, SANs, and LANs. But actually, in their practical use, there exists a common question. One may find himself faced single-mode fibers (SMFs) and multi-mode fibers (MMFs) which are terminated with different connectors, such as LC (LC fiber cable), SC (LC SC cable), MTP/MPO (MTP cable). When such things occur, it’s important to keep in mind that SMFs and MMFs are not compatible with each other, and can’t mix them together between two end points.


Fiber Optics: Advantages

Why is fiber optics used in telecommunications? There are several reasons that make fiber systems more popular than copper ones.

  • Large Bandwidth & Long Distance

Bandwidth refers to the amount of data that can be passed along a cable in a given time period. If we think of cables as pipes, then bandwidth is the amount of water that can flow through the pipe in a second. The bigger the pipe, the more water can flow. Consider a normal communication cable that may be used to carry a single phone call. It is built out of copper, and may have the bandwidth of a normal drinking straw. By comparison, a fiber cable of the same physical size would provide more bandwidth.

Since fiber optic signal is made of light, very little signal loss occurs during transmission, and data can move at higher speeds and greater distances. In most cases, copper cables are limited to a range of 100meters or less. In contrast, the relatively small diameter and light weight of fiber optic cables can allow a wide range of distance reaches from 550meters to dozens of kilometers, which makes fiber ideal for applications where signals have to travel over long distances.

  • Immunity & Reliability

Fiber optics provides extremely reliable data transmission. It’s completely immune to many environmental factors that affect copper cable. The core is made of glass, which is an insulator, so no electric current can flow through. It’s immune to electrometric interference and radio-frequency interference (EMI/RFI), crosstalk, impedance problems, and more. You can run fiber optic cable next to industrial equipment without worry. Fiber is also less susceptible to temperature fluctuations than copper and can be submerged in water.

  • Security

The data is safe with fiber cable which doesn’t radiate signals, letting information difficult to be tapped. More specifically, the dielectric nature of fiber optic cable makes it impossible to remotely detect the signal being transmitted within the cable. If the cable is tapped, it’s very easy to monitor because the cable leaks light, causing the entire system to fail. If an attempt is made to break the physical security of your fiber system, you’ll know it. Fiber networks also enable you to put all your electronics and hardware in one central location, instead of having wiring closets with equipment throughout the building. They are very attractive for use in governmental institutions, finance/banking and other environments with major security concerns.


Not only public networks, but also private networking have begun to deploy fiber optics systems nowadays. Their great capabilities of long-distance signal transmission make them popular for voice and data links. As a professional fiber patch cord manufacturer, Fiberstore offers various kinds of fiber optic cables terminated with the same or hybrid connectors on the ends to cover countless applications, at really cost-effective prices. You can come here and have a try.

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A Rundown of Fiber Optic Connectors

During the rapid development of fiber optic technologies over the past decades, fiber product manufacturers and companies have released countless sophisticated equipment, during which the so-called “better mousetrap”—fiber optic connectors attract users’ attention. These smart connectors are used to terminate at the ends of fiber optic cables to form fiber optic jumper, like fiber cable LC to LC. Since a variety of splice options are available to fiber network planners today, connector types are diversified, eg. ST, SC, LC, MTP/MPO connectors. Each connector has its own unique design and therefore, pros and cons. Then question occurs, how to choose the suitable ones that are lower loss, lower cost, easier to terminate or to solve some other perceived problems? Have some ideas? If not, don’t worry. Here is a rundown of several leading connector types, introducing their strengths and weaknesses respectively.

Fiber Optic Connector Design

Most fiber optic connectors are known to be pluggable male connectors with a protruding ferrule that holds the fiber optic cables and aligns them for mating. They use a mating adapter to mate the two connector ferrules that fit the securing mechanism of the connectors (bayonet, screw-on or snap-in.). The ferrule design is also useful as it can be used to connect directly to active devices like LEDs, VCSELs and detectors. Image below helps you to get the idea of different connector sizes.

several leading connector types

Fiber Optic Connector Color Codes

In earlier ages, single-mdoe connectors are always in yellow, while multi-mode ones in orange, black or gray. But the advent of such metallic connectors as FC and ST made color coding difficult, so colored boots were often used. The TIA 568 color code for connector bodies and/or boots is Beige for multi-mode fiber (MMF), and Blue for single-mode fiber (SMF), and Green for APC (angled) connectors.

Fiber Optic Connector Types

Table listed below shows differences among several most common fiber optic connectors.

differences among several connectors

  • SC Connector

SC, sometimes referred to as square connector, was developed by the laboratories at Nippon Telegraph and Telephone (NTT) in the mid-eighties. Standardized in TIA-568-A, the SC has a push-pull coupling end face with a spring loaded 2.5mm ceramic ferrule. At first, SC was not widely used because of its high cost, but with manufacturing costs coming down, it slowly grew in popularity in datacoms and telecoms applications including point to point and passive optical networking.

  • LC Connector

LC connector, licensed by Lucent Technologies, is a small form factor connector that utilizes a latch as opposed to the SC locking tab, and with a 1.25mm ferrule, half the size of the SC. It’s just because of its smaller size, LC becomes increasingly popular in datacoms and other high-density patch applications, as its combination of small size and latch feature make it ideal for densely populated racks/panels. With the introduction of LC compatible transceivers (say SFP-10G-SR) and other networking components, its steady growth in the communication arena is likely to continue.

  • FC Connector

Different to the plastic bodied SC and LC, FC uses a round screw-type fitment made from nickel-plated or stainless steel. The connector end face relies on an alignment key for correct insertion and is then tightened into the adaptor/jack using a threaded collet. Despite the additional complexity both in manufacturing and installation, it’s still the connector choice for precise measuring equipment such as OTDRs.

  • ST Connector

ST was developed by AT&T. Judging from appearance, ST and FC are almost the same, except that ST uses a bayonet fitment rather than a screw thread. The introduction of SC and LC has reduced the usage of ST and FC, since SC and LC deliver similar performance to ST and FC, but both have less expensive components and are quicker to connect. Additionally, ST cannot be terminated with an angled polish, which limits use in SMF and FTTH applications.

  • MTP/MPO connector

Just like SC, MT ferrule connector is also NTT’s invention coming in the 1980s. But this technology has only recently become popular under branded versions of the multiple fiber push-on/pull-off connector, such as MTP and MPO. It is larger than the other connectors but for good reason – it can support up to 24 fibers in a single ferrule. They are extensively used in high density patch environments such as data centers they are used extensively, both at single mode and multi-mode wavelengths.

It’s known that the sequence of the fibers cannot physically be changed after termination, so MTP/MPO connector is supplied with a fan-out assembly at the opposing end, such as LC. This allows the operator to change channels simply by re-patching the fanned-out side of the cable.


After description, it’s easy to identify these connectors and choose the right ones for your networking use according to their design and usage. Fiberstore supplies various kinds of connectors with high quality and at low prices. Besides, connector compatible fiber patch cords are also available, including fiber cable LC to LC mentioned above, SC SC fiber cable, ST ST fiber cable, and so on. You can visit Fiberstore to know more information about fiber optic connectors and their compatible fiber cables.

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Comparison Among Twisted Pair, Co-axial Cable and Fiber Optics

In communication systems, massive bundles of wires and cables are used to transport data between servers and other equipment. These cables can be twisted pair cables, co-axial cables and fiber optic cables. Since all these three types can be applied to network communications, it’s essential to determine which cable type is the best for the reliable and efficient data transfer, meaning that a basic understanding of their respective designs and features is necessary. This text aims to compare these three kinds and discuss the differences among them.

Twisted Pair Cable

Twisted pair cable is a kind of wiring in which two conductors of a single circuit are twisted together, with one conductor serving as the forward circuit and the other as the return circuit. The twisted cabling design helps to reduce noise from outside sources and crosstalk on multi-pair cables, making it suitable for use in the field of telecommunication for a long time.

Twisted pair cable comes in two versions (image shown below): unshielded twisted-pair (UTP) and shielded twisted-pair (STP). Since UTP cable lacks shielding, it’s more susceptible to interference from electronic devices. Or in another way, STP cable consists of a foil jacket which helps to prevent crosstalk and noise from outside source. STP is commonly used in Token Ring networks and UTP is in Ethernet networks.


Co-axial Cable

Co-axial cable, or sometimes referred to as coax, is a type of cable that has four layers. That is, at the core is an inner conductor which is surrounded by a foam insulation, symmetrically surrounded by a woven braided metal shield, then covered in a plastic jacket (just as the following picture shows). Because of its insulating property, coaxial cable can carry analogy signals with a wide range of frequencies. It’s seldom used in computer networks anymore, but widely used in cable television services and video connections, like those used by closed circuit surveillance systems.

coaxial cable structure

There are two coaxial cables: 75 Ohm and 50 Ohm. The former is primarily used to transmit a video signal, like television signals over cable. While the main application of the latter is transmission of a data signal in a two-way communication system. Other typical applications include computer Ethernet backbones, wireless antenna feed cables, GPS (Global Positioning Satellite) antenna feed cables and cell phone systems.

Fiber Optic Cable

Fiber optic cable is the complete assembly of fibers, and uses light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Each of the optical fiber elements is individually coated by plastic layers and contained in a protective tube. A fiber optic cable can accommodate many wavelengths (or channels), able to accommodate ever-increasing data capacity requirements. When terminated with LC/SC/ST/FC/MTRJ/MU/SMA connectors on both ends, such as LC-LC, LC-ST, SC-SC, ST-ST, LC SC cable, fiber optic cables can achieve fiber link connection between equipment during fiber cabling.

LC SC cable

Comparison Among Three Cables

Before delving into comparison between these three cables, a table about their respective strengths and weaknesses is available.

twisted pair vs. coaxial vs. optical fiber

  • Comparing Twisted Pair & Co-axial Cable

Both twisted pair and co-axial cable can support network speeds in both the megabit and gigabit ranges. Both are susceptible in varying degrees to signal interference, as well as signal leakage. (Signal interference occurs when external signals interfere with transmission inside the cable, and signal leakage means that signals inside the cable leak out and become a source of interference to other devices.) Coaxial cable, being of a standard design, varies little in its susceptibility to interference. For twisted pair cable, however, the cable’s resistance to interference depends in large part on the degree to which the twisting scheme remains in place, and therefore can vary widely.

  • Comparing Twisted Pair & Fiber Optic Cable

Judging from cable and installation costs to tooling and transceivers, twisted pair, here mainly refers to UTP, is much less costly than fiber optic cable. The one obvious difference lies in the quality. Passive to active UTP systems offer performance similar to fiber, providing noise immunity, attenuation compensation, surge protection and ground loop isolation. Because of this point, those users, who once deployed fiber optic cables for runs beyond the range of co-axial cable, now choose UTP for transmission. Fiber optic cable is good for extremely long runs (over one mile) or for safety when video is run in the same conduit with high voltage.

Allowing for distance, if cable runs less than 250 feet, co-axial cable is probably the best option. Between 250 and 8,000 feet, UTP wire is often the best one. If the runs are more than 8,000 feet, it’s advised to select fiber optic cable.


While deciding whether to use co-axial cable, twisted-pair, or fiber optic cable for transmission, it’s imperative to collect the basic information about them, and take the cost, cable runs and other external conditions into consideration. In Fiberstore, you can find different types of UTP cable (eg. Cat 5, Cat5e, Cat6) and various fiber optic cables (say LC SC cable mentioned above, SC to SC fiber patch cable). You can go to Fiberstore to know more information about both copper and fiber optic cables.

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Fan-out Technology Used in 40GbE Deployment

Obvious is the growing need for bandwidth required to accommodate various cloud services, smooth multimedia downloads or uploads, video streaming, as well as growing wireless usage. 10Gbps links are not sufficient enough to handle the increased bandwidth. As such, it’s imperative to deploy Higher Speed Ethernet (HSE) network, say 40GbE, by using devices that scale to match customer demands. Besides adding more devices and cables, higher port density is also the ideal solution to get greater bandwidth. To deliver the higher HSE port density for 40GbE interfaces, fan-out (breakout or harness) cabling technology is introduced here which also meets the need to keep costs at a manageable level.

Fan-out Technology Basics

Being one of the latest enabling technologies to help increase port densities and lower costs, fan-out technology is easy to be grasped. At first sight, a fan-out cable looks very simple. It takes one (large bandwidth) physical interface and breaks it out into several (smaller bandwidth) interfaces. A typical example of this is QSFP to SFP+ cable assembly which takes one 40G QSFP interface on one end and uses a fan-out cable to break it into four SFP+ interfaces one the other end. In this QSFP+ assembly, a fan-out cable enables splitting out the 4 lanes into Tx/Tx pairs usable for 10GE transmissions.

However, the truth is not definitely just as its face. This complex fan-out technology is critically important in the distribution layer of 40G data center. The following passages discuss two fan-out assemblies that are widely used in 40G data center.

40G MPO/MTP Fan-out Cables

Here goes to the MPO/MTP fan-out cables in 40GbE transmission firstly. A MPO/MTP fanout cable is a multi-fiber optical cable that contains several individual tight buffered optical fibers with one end terminated with a male/female MPO connector and the other end usually terminated with several LC connectors. Existing 40Gbps transmission over this multi-mode backbones is accomplished by using an LC to MPO fan-out assembly to connect the existing LC connectors in the installed cabling to the MPO connector in the 40Gbps.

40G connection with LC distribution module

There are many MPO fan-out cable types. For 40G cabling, the most common breakout cable type is the one which is able to fan out into 12 fibers. (a typical 12-fiber MPO breakout cable often with OM3 optical fiber as the transmission media is shown below). This 12-fiber MPO fan-out cable is terminated with 6 duplex LC connectors on one end and a male MPO connector on the other end, which can work from MPO trunk backbone assemblies to LC fiber rack system in high density backbone cabling from 40G device to 10G devices.

12-fiber MPO fan-out cable

40G Direct Attach Fan-out Cables

Direct attach cable (DAC), as a kind of optical transceiver assembly, is also available in fan-out design. It’s a form of high speed cable with “transceivers” on either end used to connect switches to routers or servers. Although the “transceivers” on both ends of DACs are not real optics and their components are without optical lasers, they perform the similar functions as the real transceivers. DAC fan-out cables can be divided into direct attach copper breakout cables and active optic fan-out cables.

40G DAC fanout cable: DAC copper vs. AOC

Converting one form factor to a different form factor is necessary in many cases. For example, a 40G device may be connected to one or several 10G devices for distribution or adapting. With fan-out DAC, this process would be much easier. This pre-terminated components can also increase the reliability of data center effectively.

Fan-out Technology Consideration

One important consideration for fan-out technology is that for each group of fan-out ports, there must also be a MAC (media access control) engine and the entire IEEE reconciliation layers behind it. For example, a 40GE QSFP port in fan-out to 4x10GE links must have four individual 10GE MACs running behind each group of electrical lanes. The port electronics must be able to switch from a single 40GbE MAC to 4 10GbE MACs, and back again to a single 40GE MAC. This process is integral in assuring that the lanes have a correct and trackable MAC assignment — it is crucial to make fan-out technology actually work.


40G fan-out technology separates a single physical interface into multiple physical interfaces that are 410GbE-capable, providing high-density interfaces over multiple speeds. This increases interface flexibility at lower costs. Fiberstore offers a wide selection of fan-out MPO and DAC cables (QSFP to SFP+ cable) for your 40G transmission. Besides these 40G cables, 40G modules which are fully compatible with major brands can also be found, such as Cisco QSFP-40G-SR-BD. This compatible module just costs you US$ 300.00 at Fiberstore, but when you search it on Amazon or somewhere else, it seems that you have to pay more than US$ 400.00 for a new one.

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Considerations About Fiber Patch Cord Purchasing

Tough were those old days in the field of data communications when users had to take coppers wires as the medium to transmit data and many were looking to save money as much as they can in cabling installations and upgrades. But owing to the rapid advances of fiber optic technology over the years, fiber optic patch cords have been heavily deployed to deliver more bandwidth for significantly longer distance transmission, with very little signal loss during transmission.

Fiber optic patch cord, also called fiber optic patch cable, fiber patch cord, or fiber optic jumper, is short interconnection fiber optic cable with connector on each end. Installers often use patch cords to link the equipment and components in the fiber optic network, eg. to connect the fiber optic converter and termination box. The commonly used fiber optic jumper types include SC patch cord, ST patch cord, LC patch cord, as well as MPO cable according to different connector types. Since patch cords come in many types, do you feel at a loss while purchasing them? What’s your consideration? This article lists several parameters that need to be considered when buy patch cords.

Connector Type & Its Performance

Certainly, price comes as the most direct factor for notice, the connector type and performance seem to be more important when choosing fiber jumpers.

Various standard connectors are provided by some manufacturers, including ST, SC, MPO, LC, etc (shown below), enabling installers to choose the most suitable connector type to fit the job. Patch cord connectors should be visually inspected and optically tested. There are fundamental parameters that affect the connector performance: low insertion loss and low reflectance. Insertion loss (IL) must be in accordance with the Electronic Industries Association/Telecommunications Industry Association standard 568. Reflectance, also known as optical return loss, is the amount of light that is reflected back up the fiber toward the source by light reflections off the interface of the polished end surface of the mated connectors and air. Minimizing the reflectance is necessary to get maximum performance out of high bit rate laser systems. Good connectors with proper polish are greatly needed. Properly made fusion splices will have no refelctance; a reflectance peak indicates incomplete fusion or inclusion of an air bubble or other impurity in the splice.

various connector types

Cable Size & Its Type

Besides connector type and performance, what else should be considered? Certainly, the fiber size and type need to be specified.

Fiber optic cable is available in two versions: single-mode fiber (SMF) and multi-mode fiber (MMF) based on “mode”. The form.er usually in yellow, is designed with a core diameter between 8 and 10.5µm. There are two sub groups (referred to as OS1 and OS2) but most cable is “dual rated” to cover both classifications. In contrast, the latter, usually in orange, has a larger core size, typically 62.5µm or 50µm. With the 50µm diameter MMF, there are three different grades (referred to as OM2, OM3, and OM4). The cable types used in the patch cord should match that of the network cabling to which they are attached via the patch panel.

single-mode vs. multi-mode fiber

Fiber patch cable assemblies can also be simplex or duplex. Simplex patch cord is typically one 3-millimeter cord that goes from point to point. It has a single strand of fiber allowing for signal flow in one direction only. Duplex patch cord has two fibers molded together with a zip cord so you can separate them. Multi-fiber or high-fiber-count optical harnesses assemblies have also been brought to the market.

simplex vs. duplex patch cable

Other Parameters

Other parameters that attract installers’ attention are the price and installation. For instance, the possible length is 1m from one port to another port. And when the patch panels are in a couple of racks or if a full rack is allocated to a set of patching, the length could be 2 meters. However, if it`s a piece of electronics over to a patch panel over to a big switch room, that could be 10 meters.

Installation is of great importance, because the whole fiber optic system performance can be affected by dirty connectors on patch cords. The best principle is that any time a connector is unplugged or remated, it should be cleaned carefully so as to avoid dirt, oil, or something else that would degrade the network performance.


Fiber patch cords can be used to provide interconnection between the optical transmission equipment and the patch panel, able to connect one port on a patch panel to another port. As a professional fiber optic product manufacturer, Fiberstore supplies all kinds of patch cords, such as SC patch cord, ST patch cord, LC patch cord, MPO cable, simplex/duplex patch cable, and so on. Want such patch cords for installation, welcome to visit Fiberstore.

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