Connectivity Considerations for 10G Ethernet

The exploding demand for Internet access to web-based applications, as well as integrated multimedia applications, has fueled the need for higher-bandwidth networks. 10G Ethernet, which takes the advantages of fast data transmission, good network performance and cost-effective property, has become commonplace for current network backbones and data centers to meet such increasing demand for faster speed network. Many companies and individuals are ready to upgrade networks to 10G infrastructure by themselves. What connectivity options can we use to achieve an efficient and smooth 10G Ethernet network? Read this post, and you will get some information.

10 Gigabit Ethernet

10 Gigabit Ethernet, first defined by the IEEE 802.3ae-2002, is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. Different from the previous Ethernet standards, 10G Ethernet defines only full duplex point-to-point links which are generally connected by network switches, while like previous Ethernet standards, it can use either high-grade copper or fiber cabling, like cat6a or cat7 Ethernet cable for lengths up to 100 meters. The following table shows common 10GbE standards.

10G Connectivity Options

10G Fiber Optic Transceiver

Fiber optic transceivers are the most commonly used component to achieve 10G data rate in telecommunications applications. They are housed and available in modules specified by multi-source agreement (MSA) which are created by module manufacturers and equipment OEMs. Over the past years, the form factor had evolved from XENPAK to X2 to XFP to SFP+ modules (as shown below).

• XENPAK: XENPAK was supplied for physical layer interfaces supporting multimode and single-mode fiber optic cables and Infiniband copper cables with connectors known as CX4. It can achieve transmission distances varying from 100 m to 80 km over fiber and up to 15 m over CX4 cables. Since it is large and bulky, XENPAK modules have been gradually replaced by the newly reported transceiver modules.
• X2: Like XENPAK, X2 transceiver can also support all the 10GbE standards, but it is about 2/3 the size of XENPAK, allowing for more port density on switches. X2 provides customers with a strong sense of assurance that this technology is the best choice for today and will have strong vendor support.
• XFP: XFP transceiver is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. It is a slightly larger form factor than the popular SFP+ transceivers, so it can allow switch vendors to increase port density in a smaller area for cost savings.
• SFP+: SFP+ transceiver is the predominant 10G Ethernet connector, which is an extension of the SFP optical transceiver, designed to increase the capacity of the existing SFP module. This type of 10G module has attracted many customers, since it can achieve 10G speeds and has a mechanical form that allows 1G or 10G to reside in the same footprint.

10G Fiber Optic Cabling

As another type of 10G connectivity option, fiber optic cable, with large transmission capacity, strong anti-electromagnetic interference, high security and fast speed, also enjoys great popularity in 10G applications, such as remote campus connectivity, crowded wiring closets, long-distance communications and environments that need protection from interference. LC fiber patch cable (see in the following image) is one of the most common cables for 10G Ethernet, covering single-mode and multimode categories respectively for data transmission over long distance and short distance.

10G Copper Cabling

Copper cabling is popular for transmitting data between devices due to its low cost, easy installation and flexibility. The commonly used 10G copper-based options are 10G SFP+ twinax cable and 10GBase-T.

• SFP+ twinax cable: 10G SFP+ twinax direct attach cable (DAC) integrates transceivers with twinax cables into an energy efficient, low-cost, and low-latency solution. It features SFP+ connectors on both ends, thus eliminating the need for expensive SFP+ transceivers. This type of option is only available for short data transmission distance. The following picture is a 1m Cisco SFP-H10GB-CU1M from Fiberstore.
• 10GBase-T: 10GBase-T, also known as IEEE 802.3an, can support 10Gbit/s communications over unshielded twisted pair cabling. This option probably looks similar to the RJ45 ports and cabling you use to connect your laptop to a normal network jack, but the difference is that you should specialized network adapters with ports that support faster 10G throughput. Cat6 or cat6a cabling (as shown below) is typically used with 10GBase-T. Cat6 is specified for distances up to 55 m, while cat6a is for up to 100 m.

Summary

Fiber optic transceiver, fiber optic cabling and copper cabling are three main connectivity options for 10G Ethernet. If you need to upgrade to 10G infrastructure, you should take these three options into consideration. And all of these equipment can be purchased in Fiberstore with high quality and low price. For more information, kindly visit FS.COM or sales@fs.com.

BiDi Fiber Optic Transceiver Overview

As we all know, common optical transceivers, like SFP+, SFP, normally require two fibers to achieve data transmission between switches, firewalls, servers, routers, etc. The first fiber is dedicated to receiving data from networking equipment, while the other is to transmit data to the equipment. With the development of technology, a new class of pluggable optical transceiver—BiDi fiber optic transceiver has been developed to combine the transmit and receive functions onto a single fiber (single-mode or multimode). The image below shows the differences between common optical transceiver and BiDi transceiver. How does BiDi transceiver achieve the transmission of optical channels on a fiber propagating simultaneously in both directions? What are the most commonly used BiDi transceivers available on the market? Is it worthwhile to use this kind of transceiver which is much more expensive than standard transceiver? The following test will provide more details from these three aspects.

How Does BiDi Fiber Optic Transceiver Work?

BiDi fiber optic transceiver is also called as WDM transceiver, since it is fitted with WDM coupler, which helps to combine and separate data transmitted over a single fiber based on the wavelengths of light. Unlike common optical transceivers use two fibers for duplex transmission, BiDi transceiver uses two different wavelengths to carry the duplex signals separately. The optical signals for transmitting and receiving are separately converted into signals of specific wavelengths as shown in the following image. This is why BiDi transceiver module can achieve the transmission of optical channels on a fiber propagating simultaneously in both directions.

Three Commonly Used BiDi Transceiver Types

Currently, there are a lot of fiber optic transceivers designed with BiDi technology available on the market, but the most commonly used ones are BiDi SFP, BiDi SFP+ and BiDi QSFP+. The following part will introduce them one by one.

BiDi SFP: BiDi SFP (shown in image below), compliant with the SFP multi-source (MSA), is specially used for the high-performance integrated duplex data link over a single optical fiber. It uses a long wavelength DFB laser diode, enabling data transmission up to 80 km on a single fiber. Generally, BiDi transceiver can be produced with LC simplex port which is used both for transmitting and receiving. Nowadays, it is one of the most popular industry formats supported by many fiber optic component vendors.

BiDi SFP+: Like BiDi SFP, BiDi SFP+ (see following image) is also connected by simplex LC fiber cable. Currently, BiDi SFP+ transceivers using 1270 nm and 1330 nm for transmission are most commonly used for 10G transmission. And it can achieve 10G data rate for the link lengths of 10 km, 20 km, 40 km, and 80 km. When you select BiDi transceivers, please take these two factors into consideration.

BiDi QSFP+: BiDi QSFP+ transceiver is a latest product used for 40G short-reach data communication and interconnect applications. Compliant with the QSFP MSA specification, it is terminated with a duplex LC connector interface to transmit data over laser-optimized OM3 and OM4 multimode fiber cables for the length of up to 100 m and 150 m respectively, that is the same as the traditional QSFP-40G-SR4. This 40G transceiver has two 20G channels, and each channel transmits and receives two wavelengths over a single multimode fiber strand. The following picture is a BiDi QSFP+ transceiver.

Why Should We Use BiDi Fiber Optic Transceiver?

Generally, BiDi fiber optic transceivers are much more expensive than common fiber optic transceivers. From Fiberstore, a Cisco SFP-10G-SR is 16 dollars, while a cheapest Cisco BiDi SFP+ transceiver is 50 dollars. Is it worthwhile to use this kind of transceiver? The answer is definitely yes.

As we have mentioned above, compared to traditional optical transceivers, BiDi transceivers uses fewer fibers (about 2 fibers) to support signal transmission, which can save an amount of money for you. Take BiDi QSFP+ transceiver as an example, if you are building a new 40G data center fabric in the traditional way, you would need to run 8-multimode fiber strands between your access and aggression layer: a cost of $2000 per port. However, with BiDi QSFP+ transceivers, you can get 40G performance using just 2 fiber strands: a quarter of cabling. For a standard server rack (384 ports), that translates to a savings of more than $550,000.

Summary

Although the label price of BiDi fiber optic transceiver is higher than standard optical transceiver, it is of much more value in practical applications. With the existence of BiDi fiber optic transceiver, the cost of fiber infrastructure will reduce, while the network capacity will increase. But keep in mind that BiDi transceiver is usually deployed in matched pairs to get the work most efficiently, since it uses two different wavelengths for transmission.

Twisted Pair Cable VS. Coaxial Cable VS. Fiber Optic Cable

As we all know, in every communication system, all the sending and receiving devices, like fiber optic switch, need to adopt massive bundles of wires or cables to achieve connections for data transfer. Nowadays, the most common cable types used in communication systems are twisted pair cable, coaxial cable and fiber optic cable. With these three cable types equally deployed in network communication, people may feel confused which one is the ideal choice for their networks? This article aims to introduce some differences among twisted pair cable, coaxial cable and fiber optic cable and to tell you how to distinct them from each other in terms of features and specifications as well.

Twisted Pair Cable

Twisted pair cable is a type of ordinary wiring which connects home and many business computers to the telephone company. It is made by putting two separate insulated wires together in a twisted pattern and running them parallel to each other which helps to reduce crosstalk or electromagnetic induction between pairs of wires. Twisted pair cable is good for transferring balanced differential signals. The practice of transmitting signals differentially dates back to the early days of telegraph and radio. The advantages of improved signal-to-noise ratio, crosstalk, and ground bounce that balanced signal transmission brings are particularly valuable in wide bandwidth and high fidelity systems.

According to whether the cable has a shielding layer, there are two common types of twisted pair cables—shielded twisted pair (STP) cable and unshielded twisted pair (UTP) cable. STP cable is available for Token Ring networks, while the UTP cable is more suitable for Ethernet networks. The most common UTP cable types applied in Ethernet network are cat5e, cat6a and cat7 cables, etc. The following image shows the different structure of UTP and STP cables.

Pros: Twisted pair cable is more flexible and cheaper than coaxial cable and fiber optic cable, and it is easy to install and operate.

Cons: It encounters attenuation problem and offers relatively low bandwidth. Besides, it is susceptible to interference and noises.

Coaxial Cable

Like twisted pair cable, coaxial cable or coax cable is another type of copper cable which has an inner conductor surrounded by a foam insulation, symmetrically wrapped by a woven braided metal shield, then covered by in a plastic jacket (as shown in the following image). This special design allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other types of transmission lines. Coaxial cable acts as a high-frequency transmission cable while contains a single solid-copper core, and compared to twisted pair cable, it has over 80 times the transmission capability. This kind of cable is mainly adopted in feedlines connecting radio transmitters and receivers with their antennas, computer network connections, digital audio (S/PDIF), and distributing cable television signals. 75 ohm coaxial cable and 50 ohm coaxial cable are two coaxial cable types. 75 ohm cable aims to transmit a video signal, while the 50 ohm cable is designed to transmit data signals in a two-way communication system.

Pros: Coaxial cable can be installed easily, relatively resistant to interference.

Cons: It is bulky and just ideal for short distance transmission.

Fiber Optic Cable

Unlike twisted pair cable and coaxial cable with wires inside, fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting message modulated onto light waves. There exist various types of fiber optic cables, which are determined by the number of fibers and where it will be installed. Currently, two types of fiber optic cables are widely adopted in the field of data transfer—single-mode fiber optic cable and multimode fiber optic cable. A single-mode fiber optic cable has a small fiber core and only allows one mode of light to pave through at a time, so it is available for high-speed and long-haul applications. By contrast, a multimode fiber optic cable has a much bigger fiber core and it can carry multiple light rays at a time, so it is more ideal for short distance data transmission. The following table shows some differences between single-mode and multimode fiber optic cables.

Pros: Compared to the above mentioned copper cables, fiber optic cable takes more advantages, such as lighter, better performance and higher bandwidth. But the biggest advantage of fiber optic cable is that it can transmit much more data with the lowest loss at higher speed for longer distance.

Cons: Nevertheless, it needs complicated installing skills, and much more expensive than copper cables.

Conclusion

Whether to choose twisted pair cable, coaxial cable or fiber optic cable totally depends on the specific circumstances where you should take cost, performance and supporting transmission rate and length into consideration. Through this passage, hope you can figure out the differences between these three cable types.

Fiber Optic Attenuator Overview

As we all know, a fiber optic amplifier is often installed where optical signals are weak and need to be enlarged. But what if there is too much power level of an optical signal which should be reduced? To solve this issue, fiber optic attenuator comes into being. Fiber optic attenuator or optical attenuator is a passive device utilized to decrease the power rate of the optical signal either in free space or in an optical fiber without appreciably distort the waveform. This article will give an overview of optical attenuator to make you better understand it.

The Importance of Fiber Optic Attenuator

Many people may think that the bigger the optical signal, the better the performance. Actually, either too little or too much power can cause high bit error rates. Too much power can make the receiver amplifier saturate, while too little will cause noise problems as it interferes with the signal. For example, in DWDM system, multiple wavelength channels arriving at a node may pass through different paths and experience different losses, their powers need to be equalized before entering the optical amplifier to get flat since the gain of each channel depends on the power level of the other channels. So in this case, a fiber optic attenuator is required to control the power level of optical signals.

How Does a Fiber Optic Attenuator Work?

The power reduction is done by means such as absorption, reflection, diffusion, scattering, deflection, diffraction, and dispersion, etc. The fiber optic attenuator usually works by absorbing the light, like sunglasses absorb extra light energy. Using this working principle, fiber optic attenuators typically have a working wavelength range in which they absorb all light energy equally, and should not reflect the light or scatter the light in an air gap which could cause unwanted back reflection in the fiber system. This kind of principle is more popular in the design of optical attenuator, since it is simple and can effectively reduce the optical signal power. The following picture shows the absorptive principle of optical attenuator.

Types of Fiber Optic Attenuator

Optical attenuator is widely used in fiber optic communications, either to test power level margins by temporarily adding a calibrated amount of signal loss, or to be installed permanently to properly match the levels of a transmitter and a receiver. There are two commonly used types, including fixed attenuator and variable attenuator.

Fixed attenuator, as its name shows, is designed with an unchanging level of attenuation that is ideal for attenuating single-mode fiber connectors in various applications. It can be theoretically designed to provide any amount of attenuation that is desired and be set to deliver a precise power output. This type of optical attenuator is utilized in structure for two distinct types of services. On the first type, it is used to regulate the channels in order to set up a recognized level of signal. On the second type, this mechanism is used to match the impedance and also as a shield to avoid the contact with two different device. A LC fixed fiber optic attenuator is shown in the image below.

Different from fixed attenuator, variable attenuator can offer a wide range of attenuation values with flexible adjustment which is generally used for testing and measurement or equalizing the light power among different channels in EDFAs. This type of optical attenuator can be divided into stepwise variable attenuator and continuously variable attenuator. The former one can change the attenuation of the single in known steps such as 0.1 dB, 0.5 dB, or 1 dB, while the latter one can allow the operators to adjust the attenuator to accommodate the changes required quickly and precisely without any interruption to the circuit. Like fixed attenuator, both these two types of variable attenuators are available with regular connectors, like LC, SC or FC. Here is a LC to LC variable fiber optic attenuator.

Conclusion

As an indispensable passive optical component in WDM networks, fiber optic attenuator is designed to control the power level of optical signals more precisely. We have discussed the importance, working principle and commonly used types of fiber optic attenuator. Hope you can have a better understanding of it.

How to Easily Upgrade Your Network to 40G Ethernet

The increasing need for higher bandwidth and faster data transmission drives the evolution of network Ethernet. 40G Ethernet is gradually becoming commonplace in telecommunication networks, as 10G cannot satisfy the never-stopping longing for higher speed communication any more. Unlike 1G migrating to 10G, 10G migrating to 40G gets across a much larger span in terms of not only transmission data rate but also technologies. Thus, the deployment of 40G is much more complicated than that of 10G. Today, I’d like to introduce several indispensable components to help those who want to easily upgrade their network to 40G Ethernet.

QSFP+ Fiber Optic Transceiver

Fiber optic transceiver is a very basic component in today’s telecommunication network. It is composed of both a transmitter and a receiver that are arranged in parallel so that they can operate with their own circuity that enables each of them to handle transmission in both directions. There are different types of optical transceivers for different Ethernet networks, such as GBIC for 1G, SFP+ for 10G, CFP for 100G. As for 40G data transmission, QSFP+ (quad small form-factor plus) transceiver module is the most commonly used type.

QSFP+ transceiver (shown in picture below) is a compact, hot-pluggable transceiver, which is evolved from QSFP transceiver, used for high-speed data communications applications. It provides four channels of data in one pluggable interface, with each channel capable of transmitting data at 10Gbps and supporting a total of 40Gbps. The 40G QSFP+ transceiver offers customers high-density 40G connectivity option for data center, high-performance computing networks, enterprise core and distribution layers, and service provider transport applications.

High-Density MPO/MTP Cables

Unlike standard fiber patch cables with the maximum data rate of 10Gbps, a patch cord terminated with 12-fiber or 24-fiber MPO/MTP connectors is available for 40G, or even 100G Ethernet. MPO/MTP trunk cable and MPO/MTP harness cable are the two widely applied high-density fiber cables in upgrading network to 40G Ethernet.

MPO/MTP Trunk Cable—MPO/MTP trunk cable, terminated with MPO/MTP connectors at both end, are typically available with 12 to 144 fibers and create a permanent fiber links between panels in a structured environment. With plug and play architecture, MPO/MTP trunk cable greatly reduces the initial installation and ongoing maintenance costs. Generally, 12-fiber and 24-fiber MPO/MTP trunk cables are respectively commonly used types for 40G and 100G applications. Here is a 72-fiber MPO/MTP trunk cable with 6 MPO/MTP connectors at both ends.

MPO/MTP Harness Cable—MPO/MTP harness cable, also named MPO/MTP fan-out cable or MTP/MPO breakout cable, is terminated with a male/female MTP connector on one side and several duplex LC/SC connectors on the other side, providing a transmission from multi-fiber cables to individual fiber or duplex fiber connectors. Compared to normal LC fiber optic cable, these cables are designed for high density applications which require high performance and fast installation. MPO/MPO harness cables are ideal for interconnecting MPO/MTP cassettes, panels or backbone MPO/MTP assemblies with the active equipment, saving costly data center rack space and easing fiber management. The image below shows a 1m MTP-4LC SMM harness cable.

40G QSFP+ Cable Assemblies

40G QSFP+ cable is a cost-effective solution for 40G data center. It is a low-power alternative to optical QSFP+ system. 40G QSFP+ direct attach cable (DAC) and 40G QSFP+ active optical cable (AOC) are two types os 40G QSFP+ cables.

40G QSFP+ DAC—QSFP+ DAC is a copper 40 Gigabit Ethernet cable which comes in either an active or passive twinax cable assembly and connects directly into a QSFP+ housing. An active twinax cable has active electronic components in the QSFP+ housing, while the passive twinax cable is mainly just a straight “wire” and contains few components. Generally, twinax cables shorter than 5 meters are passive and those longer than 5 meters are active.

40G QSFP+ AOC—QSFP+ AOC is a cabling technology that accepts the same electrical inputs as a traditional copper cable, but uses optical fiber between the connectors. QSFP+ AOC uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable without sacrificing compatibility with standard electrical interfaces. The following picture shows a QSFP+ to 4SFP+ AOC and a QSFP+ to QSFP+ DAC.

Conclusion

To upgrade your network to 40G Ethernet, you should prepare components like QSFP+ transceivers, MPO/MTP fiber cables and QSFP+ cables, etc. All of these devices can be purchased in FS.COM. Just need a click, you can take all these components to home and upgrade to 40G Ethernet easily.

40G QSFP+ AOC Overview

There is no doubt that we live in a high-speed world. From fast food to the way we walk from one place to another, everything is seemingly done as quickly as possible. So does the data transmission. The speed of data transmission has evolved from 1GbE, to 10GbE and 40GbE, even to 100GbE. As 100G Ethernet is still developing and not cost effective, most data centers prefer to deploy 40G Ethernet links. 40G QSFP+ transceivers, 40G QSFP+ direct attach cables (DACs) and 40G QSFP+ active optical cables are three main fiber optics to achieve 40G interconnections in data center. Today, I’d like to introduce 40G QSFP+ AOC in details.

Introduction to 40G QSFP+ AOC

QSFP+ AOC is a high-performance and low power integrated cable solution which provides less expensive and reliable transport for aggregated data rates up to 40Gbps. It is terminated with one QSFP+ transceiver at one end, while the other end can be terminated with QSFP+ transceivers, SFP+, LC or SC connectors. 40G AOC is a four-channel parallel active optical cable, and each channel is capable of transmitting data at a rate of 10Gbps per direction, providing a total rate of 40Gbps over multimode fiber ribbon cables. Compared to 40G DAC, 40G AOC can offer more advantages, such as lighter weight, high performance, low power consumption, low interconnection loss, EMI immunity and flexibility. Nowadays, 40G AOC is widely applied in many fields and promotes the traditional data center to step into optical interconnection.

Effective Solutions for 40G QSFP+ AOC

Generally, there are three types of 40G QSFP+ AOCs available on the market. The following text will briefly introduce them one by one.

QSFP+ to QSFP+ AOC

QSFP+ to QSFP+ AOC (shown in the image below) is a 40G parallel active optical cable which transmits error-free 4×10G data over multimode fiber ribbon cables. It consists of a cable assembly that connects two QSFP+ transceiver modules respectively attached to either end of the cable. This kind of cable is usually applied in rather short distances and provides an efficient way to establish a 40G link between QSFP+ ports of QSFP+ switches with less cost.

QSFP+ to 4xSFP+ AOC

QSFP+ to 4xSFP+ AOC (shown in the following picture) is a breakout active optical cable which contains a 40G QSFP+ transceiver on one end and four separate 10G SFP+ modules at the other end. It offers IT professionals a cost-effective interconnect solution for merging 40G QSFP+ and 10G SFP+ enabled host adapters, switches and servers. Users can install this breakout cable between an available QSFP+ port on their 40Gbps rated switch and feed up to four upstream 10G SFP+ enabled switches.

QSFP+ to 8xLC AOC

QSFP+ to 8xLC connector breakout active optical cable (see the picture below) is a high-performance, low power consumption, long reach interconnect solution supporting 40G Ethernet and fibre channel. It provides connectivity between devices using QSFP+ port on one end and 8xLC connectors on the other end.

Prospect of Active Optical Cable

Active optical cable market, including 10G AOC, 40G AOC and 100G AOC, continues growing and attracts new entrants, like some of the world’s biggest supplier of cabling and telecom components. The applications of AOC are mainly in data center, HPC, consumer electronics, HDMI and digital signage, etc. According to the newest report, sales of active optical cables for the data center will produce 1.5 billion dollars in revenues by 2019. With the increasing need for more cost-effective cabling solutions in telecommunication networks, the market and application prospect of AOCs will have a broader development.

Summary

As people expect more information available in their fingertip, it is time to deploy cost-effective and high-performance 40G active optical cables in networks. Besides 40G AOC, Fiberstore also provides 10G AOC and 100G AOC for your references. All of these AOCs are fully compatible with the original-brand switches. For more information, please kindly visit FS.COM.

In-Depth Look at the Fiber Optic Connector

In all fiber optic system, it is necessary to join two fibers together with low signal attenuation while maintaining low reflection levels depending upon the type of system used. Fiber optic connectors are used as the mechanical and optic means for cross connecting fibers and linking to fiber optic transmission equipment. With a wide range of fiber optic connectors with different merits and demerits available on the market, many factors, like performance and cost, should be taken into consideration when choosing a fiber optic connector. Every small decision will post a significant influence on deployments speeds and costs of the fiber optic patch cables. To specifically understand the fiber optic connector, this post will give an overall look of it.

Fiber Optic Connector

An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors loss very little light due to reflection or misalignment of the fibers. In all, about 100 fiber connectors have been introduced to the market. The table below shows some optical connectors.

Commonly Used Types of Fiber Optic Connectors

With so many fiber optic connectors used in fiber optic networks, there are only a few types widely applied. In this part, we will introduce five types of optical connectors

FC Connector

The FC connector was the first optical fiber connector to use a ceramic ferrule, but unlike the plastic bodied SC and LC, it utilizes a round screw-type fitment made from nickel-plated or stainless. The connector end face relies on an alignment key for correct insertion and is then tightened into the adapter/jack using a threaded collet. Although the FC adds complexity both in manufacturing and installation, it is still the connector of choice for precise measuring equipment such as OTDRs. What’s more, the FC connector does make it particularly effective in high vibration environments, ensuring that the spring-loaded ferrule is firmly mated.

ST Connector

Originally developed by AT & T shortly after the arrival of FC, ST or straight tip connector was one of the first connector type widely implemented in fiber optic networking applications. ST connector can be easily mistaken for FC connector at a glance, but the ST uses a bayonet fitment rather than a screw thread. Deployed predominately in multimode datacoms, it is available in network environments such as campuses, corporate networks and in military applications where the quick connecting bayonet had its advantages at the time. Nevertheless, it cannot be terminated with an angled polish, which limits use in single-mode fiber and FTTH applications. It is typically installed into infrastructures that were built at the turn of the century, but nowadays it has almost been swapped out for more cost-effective SC and LC connectors.

SC Connector

The SC or subscriber connector was developed by the laboratories at Nippon Telegraph and Telephone (NTT) in the mid-eighties, which was one of the first connectors to hit the market following the advent of ceramic ferrules. SC connector is a non-optical disconnect connector with a 2.5 mm pre-radiused zirconia or stainless alloy ferrule. It uses a push-on/push-off mating mechanism which is generally easier to use than the twist-style ST connector when in tight spaces. Due to its excellent performance, SC connector has dominated fiber optics for over a decade and now it remains the second most common connector for polarization maintaining applications.

LC Connector

Considered to be the replacement of the SC connector, LC or lucent connector is the most popular small form factor (SFF) connector. Like SC, it is also a push-pull connector, but LC utilizes a latch as opposed to the SC locking tab. Having half the footprint of the SC connector, about 1.25 mm ferrule, gives it huge popularity in datacoms and other high-density patch applications. With more and more density increasingly needed in data centers, the popularity of LC connector will continue growing. The following picture shows the different appearance of FC, ST, SC and LC connector, so you can easily distinguish them.

MPO/MTP Connector

MPO and MTP are compatible ribbon fiber connectors based on MT ferrule which allow quick and reliable connections for up to 24 fibers, so they are larger than the connectors we have mentioned above. MPO and MTP connectors feature male and female connector design. Male connectors have two guide pins and female connectors do not (see in the following image). Both connector types need an adapter to mate a pair of male and female connectors. Since MPO and MTP connectors are trying to align so many fibers at once, their coupling losses are typically bigger than single fiber connectors. This type of connector is extensively used with a fan-out assembly at the opposing end (such as LC, SC, FC etc.) in high-density patching environments, like data centers.

Summary

Knowing the differences among different connector types is necessary to get a deep understanding of the fiber optic connector. Taking time to select the right optical connector for the job can deliver big benefits when it comes to speed and cost. So before making connector choice, please think twice.

Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration

In 2002, the IEEE ratified the 802.3ae standard for 10GbE over duplex fibers (one fiber transmits and the other receives) terminated with duplex LC-style connectors and vertical cavity surface-emitting laser (VCSEL) transceivers. With the increasing need for high speed data transmission, in 2010, the IEEE ratified the 802.3ba standard for 40/100G to satisfy this demand. Similar to how transportation highways are scaled to support increased traffic with multiple lanes at the same speed, the 40/100G standards use parallel optics, or multiple lanes of fiber transmitting at the same speed. Running 40G requires 8 fibers, with 4 fibers each transmitting at 10Gbit/s and 4 fibers each receiving at 10Gbit/s. Running 100G requires a total of 20 fibers, with 10 transmitting at 10Gbit/s and 10 receiving at 10Gbit/s. Both scenarios call for high-density MPO-style connectors, which can be either 12-fiber or 24-fiber. However, 24-fiber MPO/MTP cabling is often considered to be the better solution for 40/100G migration. Why? Reading this post and you will get the reasons.

12-Fiber and 24-Fiber MPO/MTP Cabling

A 12-fiber MPO/MTP connector is used for 40G Ethernet. Among the 12 fibers, only 8 optical fibers are required—4 for Tx and 4 for Rx, and each channel has a transmission rate of 10Gbps (typically 40G applications use only the 4 left and 4 right optical fibers of the 12-fiber MPO/MTP connector, while the inner 4 optical fibers are left unused). To run 100GbE, there are two solutions. One is to use two 12-fiber MPO/MTP connectors—one transmitting 10Gbit/s on 10 fibers and the other receiving 10Gbit/s on 10 fibers. The other solution is to use a 24-fiber MPO/MTP connector—20 fibers in the middle of the connector transmitting and receiving at 10Gbit/s and the 2 top and bottom on the left and right unused. 12-fiber can be both used for 40/100G solutions, but why said the 24-fiber is better than 12-fiber? The following part will explain in details. The image below shows different construction of 12-fiber and 24-fiber MPO/MTP.

Why Is the 24-Fiber the Right Migration Path to 40/100G?

Fiber Utilization to the Extreme

Using 24-fiber trunk cables with 24-fiber MPO/MTP connectors on both ends to connect from the back of the switch panel to the equipment distribution area can utilize the fibers to the extreme. As we have mentioned above, 40G will uses 8 fibers (4 Tx and 4 Rx) of the total 12-fiber trunk cable with 12-fiber MPO/MTP connectors, leaving 4 fibers unused. Nevertheless, when three 40G links are using three separate 12-fiber trunk cables, it will result in a total of 12 unused fibers, or 4 fibers unused for each trunk, which can be a waste. With the use of 24-fiber, running three 40G links will use all 24 fibers of the trunk cable, which recoups 33 percent of the fibers that could be lost with 12-fiber trunk cables, providing a much better return on investment. For 100G applications, which require 20 fibers (10 Tx and 10 Rx), a 24-fiber trunk cable can provide a single 100G link instead of using two 12-fiber trunk cables.

Spacing Saving

With more and more patch cables and optical equipment used in data centers, space is a premium. Using 24-fiber trunk cable will cause less cable congestion in already-crowded pathways, which can save more space and make cable management easier. For example, for a 40G application, it takes three 12-fiber trunk cables to provide the same number of links as a single 24-fiber trunk cable which can take about 1.5 times more pathway space.

Increasing Fiber Density

With today’s large core switches occupying upwards of one-third of an entire rack, density in fiber switch panels is critical. 24-fiber MPO connectors offer a small footprint which can ultimately provide increased density in fiber panels at the switch location.

Cost Effective

The 24-fiber data center fiber trunking and interconnect solution offers a simple and cost effective migration path from 10G-40G-100G, providing future-readiness for three generations of active equipment. With 24-fiber trunk cables effectively supporting all three applications (shown in the following picture), there is no need to recable the pathway from the back of the switch panel to the equipment distribution area.

Conclusion

With increasing concerns about the cost to upgrade and the complexity involved, data center managers need a solution that simplifies the process and provides better return on investment, while meeting both current and future needs. Taking the advantages of maximum fiber utilization, space and cost saving and high density, it is no doubt that 24-fiber MPO/MTP cabling is better solution for 40/100G migration.