Category Archives: Fiber Cabling

Advice on Patch Cable Selection for Optical Transceiver

Fibre optic network connection can’t be achieved without optical transceiver and patch cable. Optical transceiver varies from transmission media, interface, transmission distance, data rate, and brand, for example, SFP for 1000Mbps, SFP+ for 10G, QSFP+ for 40G, CFP and QSFP28 for 100G. It’s not difficult to identify these optical transceivers. But when you connect the optical transceiver to the patch cable, many details need to be noticed. This article will give you advice on how to choose the suitable patch cable for your optical transceiver.

Transmission Media—Copper & Fibre

According to transmission media of fibre optic and copper, transceivers can be divided into two kinds, copper based transceivers and fibre optic based transceivers. MSA has defined several copper based transceiver like: 100BASE-T, 1000BASE-T and 10GBASE-T. Copper transceivers are available in GBIC, SFP and SFP+ form factors, which usually has an RJ45 interface. So Cat5/6/7 cables are typically used to connect with the transceivers. Maybe Cat8 will be researched and developed to support higher data rate up to 40G sooner or later.

optical-transceiver-rj45-interface

As to fibre optic transceivers, things are more complex. For that fibre optic transceivers require different fibre patch cords which have more types. Fibre patch cables cover single-mode and multimode. Single-mode patch cable can be classified into OS1 and OS2. While multimode cables can be divided into OM1, OM2, OM3, OM4 cable. Different cables are used in different applications. Single-mode cable can support long distance transmission and multimode cable for short distance link. If the transmission distance is shorter than 500 metres, multimode patch cable is suggested. For long distance transmission, single-mode transmission is suggested. You patch-cableshould also consider that the transmission data rate can also affect the transmission distance. Let’s look at the following point.

Supported Distance and Data Rate

MSA has defined a variety of transceivers that can support different transmission distances and data rates. When you buy a fibre optic transceiver, you will find the data rate, wavelength, distance, etc. on its labeling. The following table show the basic information of most often used transceivers and supported cable type.

Description Wavelengh Data Rate Cable Type Distance
SX 850nm 1G MM 500 m
LX 1310nm 1G SM 8 km
EX 1310nm 1G SM 40 km
ZX 1550nm 1G SM 70 km
SR 850nm 10G MM 300 m
LR 1310nm 10G SM 10 km
ER 1550nm 10G SM 40 km
ZR 1550nm 10G SM 80 km
SR4 850nm 40G MM 100 m
SR10 850nm 100G MM 100 m
LR4 1310nm 40G SM 10 km

As mentioned before, single-mode patch cable is better for long distance transmission and multimode patch cable for short distance transmission. Actually single-mode patch cords can be used for different data rates in both long and short distances. But single-mode fibre optic cable will cost more. To achieve reliable performance in short distances with cost effective solutions, you should know the performance of multimode fibre optic cables. The following chart provides the detailed transmission distances and data rates information for different multimode fibre optic cables over wavelength of 850 nm for your reference.

Fibre Type 1G 10G 40/100G
OM1 300 m 36 m N/A
OM2 500 m 86 m N/A
OM3 1 km 300 m 100 m
OM4 1 km 550 m 150 m
Transceiver Interfaces

The selection of patch cable for transceiver should also consider the interfaces through which patch cords is connected to the transceiver. In addition, transceiver usually used one port for transmitting and one port for receiving. Generally, fibre optic transceivers usually employs duplex SC or LC interfaces. However, for BiDi transceivers only one port is used for both transmitting and receiving. Thus, simplex patch cord is used with BiDi transceiver.

Some 40G/100GBASE QSFP+ transceivers used MTP/MPO interfaces, which should be connected to the network with multi-fibre patch cords attached with MTP/MPO connectors. If these ports are used for 40G to 10G or 100G to 10G connection, then fanout patch cable should be used. For example, a MTP to 8 LC fanout cable can splitter 40G data rate to four 10G data rate.

Summary

Next time when you select patch cords for your fibre optic transceivers, you can consider these factors like transmission media, transmission data rate and distance, transceiver interfaces. FS.COM offers a wide range of fibre optic transceivers and patch cords. Custom service is also available. Any problem, please contact us via sales@fs.com.

Guide to Choose the Right Fiber Optic Patch Cable

Now with the fibr eoptic cable being widely used in a variety of industries and places, the requests for fibre patch are being elaborated. Fibre patch cables are being required to be improved and provided more possibilities to satisfy various application environments. Actually, many special fibre patch cables have been created to answer the market demand. But do you know how to choose right fibre optic patch cable for our network system? The following passages may give you a clear guideline to choose the suitable patch cables.

Why You Need Different Fibre Optic Patch Cables?

Fibre optic patch cable, some times also called fibre optic jumper cable, are terminated with fibre optic connectors on both ends. Due to the fact that fibre patch cable can carry more data efficiently, they play an important role in telecommunication and computer networking. And they are also used in numbers of places. Therefore, when you choose fibre patch cables, the first thing you need to know is the environment that the patch cable will be used. Indoor or outdoor? In the air or buried underground? Different environments have different requirements for cables. Let’s take armored fibre patch cable for example. Armored fiber patch cable, wrapped a layer of protective “armor” outside of the fibre optic cable, is generally adopted in direct buried outside plant applications where a rugged cable is needed for rodent resistance.

fibre optic patch cables

What You Should Concern to Choose the Fibre Optic Patch Cable?
Single-mode vs Multimode

Single-mode fibre patch cable uses 9/125um glass fibre and multimode fiber patch cable uses 50/125um or 62.5/125um glass fiber. Generally, single-mode fiber patch cables are the best choice for transmitting data over long distances. They are usually used for connections over large areas, such as college campuses and cable television networks. And most single-mode cabling is color-coded yellow. Multmode fibre patch cables are usually used in short distances. They are typically used for data and audio/visual applications in local-area networks and connections within buildings. Multimode cables are generally color-coded orange or aqua.

Simplex vs Duplex

Simplex Fibre optic cable means the cable composes of only one fibre, then a duplex patch cable consists of two fibres. Therefore, simplex fibre optic cable is common used in a system where only one-way data transfers. And duplex fibre optic cable is applied to where requires simultaneous, bi-directional data transfer.

Connector Types

On both ends of the fibre optic patch cable are terminated with a fibre optic connector (LC/SC/ST/FC/MPO/MTP). With the rapid development of optical fibre telecommunication, many different types of fiber connectors are available. They share similar design characteristics. Different connector is used to plug into different device. If ports on the both ends devices are the same, the patch cables such as LC-LC/SC-SC/MPO-MPO can be used; if you want to connect different ports type devices, LC-SC, LC-FC and LC-ST patch cables may meet your demand.

Polishing Types

It’s known to us that whenever a connector is installed on the end of fibre, loss cannot be avoided. Some of this light loss is reflected directly back down the fibre towards the light source that generated it. These back reflections will damage the laser light sources and also disrupt the transmitted signal. In order to optimise transmitting performance and ensure the proper optical propagation, the end of the fibre must be properly polished to minimize loss. Generally, there are two common polishing types: UPC and APC. And the loss of APC connector is lower than UPC connectors. So the optical performance of APC connector is better than UPC connectors.

Cable Jacket

The cable jacket is to provide strength, integrity, and overall protection of the fibre member. When choose one kind of fibre optic cables, the environment that the cables be used should be taken into consideration. Usually there are three types of jacket: PVC, LSZH and OFNP. Which one you choose depends on where you use the cables. Here are their features.

  • PVC cable resistant to oxidation, it is commonly used for horizontal runs from the wiring centre.
  • LSZH cable has a special flame-retardant coating and it is used between floors in a building.
  • OFNP cable has fire-resistance and low smoke production characteristics. It usually works for vertical runs between floors.
Conclusion

In summary, there are many factors which may affect your choices of fibre optic patch cable. So it’s important to make sense which kind of patch cable can really meet your requirements. FS can provide all kinds of fibre optic patch cables to satisfy your needs!

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LC Connector for High Density Data Centres

SC duplex connector was popular a few years ago. But as time goes on, smaller and more compact cabling components are required since the packing density of optical devices keeps increasing, namely high density. The smaller the shape, the more popular the component, just like development history of cellphone. Driven by this requirement, optic manufacturers start to produce mini components. The most widely known is the LC connector, a small form factor connector. The following article will introduce various types of LC connectors in details.

LC small form factor connector has just 1.25mm ferrule, half the size of the standard connector (compared with SC connector). Because of the high density design, LC connector solution can reduce the space needed on racks, enclosures and panels by approximately 50% throughout the network. So LC connector is a good solution for high density data centres. The LC connector uses RJ45 push-pull style plug that offers a reassuring, audible click when engaged. It makes moves, adds and changes easy and saves costs for you. Besides, the protective cap completely covers the connector end, which prevents ferrule end face from contamination and impact and enhances the network performance.

lc-lc-duplex

LC Uniboot

LC uniboot connector includes a finger latch release that there is no need for tools when making the polarity change. Some LC uniboot connectors are color-coded and labeled “A” and “B” to provide visual references when making a polarity change. The uniboot design is compatible with transceivers using the LC interface. The LC uniboot patch cords use special round cable that allows duplex transmission within a single cable, and it greatly reduces cable congestion in racks and cabinets comparing to standard patch cords. LC uniboot patch cord is perfect for high density applications. FS.COM LC uniboot patch cords are available in SM, OM3 or OM4 multimode fibre types to meet a wide variety of configurations and requirements.

uniboot-lc

Push-Pull LC Connector

If you have tried to release LC connectors in patch panels with high density, you must know how difficult it is. As to high density panel, thumbs and forefingers can not easily access to pull the connector. So some manufacturers start to offer a special LC connector which can be easily dealt with. And that’s push-pull tab LC connector.

Push-Pull-Tab-Patch-Cable

LC push-pull connectors offer the easiest solution for installation and removal. The special design is available in a compact model, ideal for minimizing oversized panels. With this kind of connector, you don’t need to leave additional space at the top or bottom to allow room for engaging the latch. The structure of the LC push-pull compact is designed as the latch can be slid back, instead of being pushed down, to facilitate smooth removal. It’s simple for installation and removal. Push-Pull LC patch cable allows users accessibility in tight areas when deploying LC patch fields in high density data centres. Push-Pull LC fibre patch cords are available in OM4, OM3 or single-mode fibre types to meet the demands of Gigabit Ethernet, 10 Gigabit Ethernet and high speed Fibre Channel.

Secure Keyed LC Connector

Secure keyed LC connectors are designed for network security and stability. 12 colors are available in FS.COM, including red, magenta, pink, yellow, orange, turquoise, brown, olive, etc. Connections only work when the color matches. The color-coded keying options provide design flexibility and facilitate network administration. It reduces risks and increases the security of network from incorrect patching of circuits. Secure keyed LC connectors feature low insertion loss, excellent durability.

lc-keyed

Conclusion

This article tells different types LC connectors, including common LC connector, LC uniboot, push-pull LC and secure keyed LC connector. The design of those LC connectors keeps improving to adapt to high density data centrers. Nowadays, the trend of network is high speed and high density. So effective cable management is significantly important. And the key concern is how to manage more cables within less space. Thus, among so many kinds of interfaces, LC connector is the most frequently used and the most effective solution for space saving in data centres.

Suggestions for Data Centre Design

The demands on data centres and networks are growing very fast. To meet communication needs, more and more devices are connected to the data centre network links. It brings difficulties in data centre management. The infrastructure design should guarantee the reliable network performance. But how to achieve the best performance? Four suggestions are recommended for you when designing a data centre.

Maximizing Network Performance

As today, many companies adopt high density configurations and virtualization to increase the capacity of existing IT equipment. To ensure the network performance, a robust data centre infrastructure is necessary. And three parts of the infrastructure must be considered: the structured cabling, racks and cabinets, and the cable management.

data-center

Figure 1. Structured data centre

First, the structured cabling performance has a close relationship to the connectivity and cable components. If the components fail to deliver good cabling system, great optical loss will be caused. To improve the channel performance, insertion loss should be minimized especially in 40G and 100G data centre. Second, choose right rack or cabinet to accommodate new equipment with different size and weight requirements since active equipment in the infrastructure turn to be broken easily and will be replaced in five years or less. Third, manage the airflow and maintain good cooling system. Because the rising temperature of the data centre has an influence on network performance. The last component of the infrastructure is cable management. A well-designed cable management should meet the standards of spare space, high reliability and scalability. The infrastructure is designed for both copper and fibre, maintaining proper bend radius for both copper and fibre, protecting cable from damage, and creating crosstalk and return loss.

Saving Time

Although data centre grows in size and complexity, it often requires faster deployment. It must adapt to the rapid changing business requirements. As it says, time is money. Selecting an infrastructure that optimize time, result in faster deployments can save lots of costs.

In order to save time in deployment, installation and future moves, adds, and changes, a suitable modular solution based on the rack or cabinet should be applied. The modular solution is also good for effective airflow management and cooling, which can save time because it can easily support high density when needed. Pre-terminated copper and fibre cabling solutions can also save time during installation and future cabling moves. Pre-terminated fibre systems, for example, MPO to MPO trunk cables or MPO to LC harness cables, can facilitate the migration to higher speeds.

Optimizing Spare Space

To adapt to high speed demands, data centre infrastructure turns to be more complex. Now space is a premium in the data centre as port densities continue to increase. Considering the cost, infrastructure should be optimized for greater flexibility and scalability. High density connectivity options including high density patch panel, MTP cassette, etc. are the solutions to optimize space while supporting large port densities. For instance, LC connectors (2 fibre) have been replaced by MPO (typically 12 or 24 fibres) connectors for the migration from 10 GbE to 40 GbE and 100 GbE.

MTP-solution

Figure 2. MTP components for saving space

To optimize space in the data centre, the following factors are needed to be considered:

  • Choose the rack or cabinet as your basic building block
  • Select racks and cabinets with higher weight limits, sufficient depth and heights that support growing vertically
  • Select cable management that can support existing and future cable density, fluent airflow, and is designed to support both copper and fibre
  • Select connectivity that supports high density and mixed media
  • Use cable with small outside diameter
  • Consider patching outside the rack and cabinet to save space for equipment
  • Select a rack or cabinet solution that easily integrates with overhead pathways
Finding a Cooperator With Rich Experience

During the design phase, the data centre design must provide guaranteed performance while providing flexibility and scalability for future needs. During the installation phase, the solution must be easy to install, quick to deploy and easy to manage. So it’s important to find a qualified contractor who has a history of quality installations. You also need to choose a good manufacturer providing cost-effective components covering cooling, power, connectivity, cabling, racks and cabinets, cable management, and pathways, like Fiberstore (FS.COM). And the manufacturer should also have expertise of extending the equipment life, reducing cost and solving other problems in the data centre.

Summary

Data centre design is not an easy job as the cabling infrastructure becomes more complex for meeting the growing high data rates demands. To maximize the efficiency of a data centre, too many elements should be taken into consideration. The above content gives suggestions for data centre design to guarantee performance, save time, optimize space, and find an experienced cooperator. Hope this article is useful to your data centre design.

MTP Trunks for High Density Data Centre

The need for high bandwidth has never stopped. High bandwidth means more fibres are needed for the cabling infrastructure. The demands certainly change the network architecture to be more complicated. For spine-and-leaf architecture, each leaf switch in the network is interconnected with every spine switch. As a result, with leaf-spine configuration in data centres, fibre counts can multiply very quickly compared with traditional three-layer distribution architectures.

Besides, 40GbE and 100GbE grow quickly in the data centre. Relatively, the interface of parallel optics like 40G QSFP+ changes to be MPO/MTP with 12-fibre instead of duplex fibre. And that also increases the fibre counts in your data centre structured cabling. As data centre evolves, links require 144 fibres, 288 fibres or even more. So data centre managers are in front of many challenges such as limited space, deployment efficiency and of course the cost.

MTP Trunks Deployment Solutions

To address these challenges, many data centre cabling designs use MTP trunks with up to 144 fibres. In data centres requiring more than 144 fibres, multiple runs of a 144-fibre cable assembly are typically installed to achieve the total desired fibre count. For example, if a link requires 288 fibres from the main distribution area of the data centre to another location, two 144-fibre trunk cables would be installed. This method can reduce the physical space capacity for future growth. Figure 1 depicts the space savings across three deployment scenarios in a 12-inch x 6-inch cable tray with a 50 percent fill ratio:

  • 4,440 total fibres using 370 x 12-fibre MTP trunks
  • 13,680 total fibres using 95 x 144-fibre MTP trunks
  • 16,128 total fibres using 56 x 288-fibre MTP trunks

comparison

Figure 1. Comparison of trunks with different fibres

MTP connectivity is one of the important solutions used in high density environment. MTP cable allows for the deployment of optical fibre termination of 12 fibres at a time rather than individual termination of single fibre strands. In addition, this kind of cabling is easy for future migration to 40/100/200/400GbE networks using parallel optical technologies. To achieve high-fibre-count cable and connectivity, various implementation options are available.

MTP Trunks

MTP trunk cable assemblies are offered in fibre types in standard 12, 24, 48, 72, 96 or 144 core versions in a compact and rugged micro-cable structure. With high port density, it brings big savings in installation time and cost. Due to its discreet premium connectors and special fibre, it delivers low insertion loss and power penalties in high speed network environment. And the multifibre connector and compact dimension also ease the space pressure in costly data centres.

MTP trunk cables are available in either mesh bundles or distribution fan-out trunks since infrastructure designs, cabling environments and pathway types are different, MTP connectivity in backbone cabling can employ different methods. Below are two possibilities:

Cables that are factory terminated on both ends using MTP connectors (MTP-MTP trunks)
Cables that are factory terminated on one end using MTP connectors (MTP pigtail trunk)

MTP-trunks

Figure 2. MTP assemblies types

MTP-MTP Trunks

MTP trunk assemblies are used where all fibres are landed at a single location at each end of the link—for example, between the main distribution areas (MDAs) and the server rows or between the MDA and the core switching racks in a computer room or data hall, as Figure 3 shows. Additionally, MTP-MTP trunks also appear between MDAs of multiple computer rooms or data halls where open tray is the pathway.

same-computer-room

Figure 3. MTP-MTP trunk assembly deployed in a computer room

MTP Pigtail Trunks

MTP pigtail trunks can be used for environments where the pathway doesn’t allow for a pre-terminated end with pulling grip to fit through—for example, a small conduit space (see Figure 4). This approach is common when needing to provide connectivity between MDAs of multiple computer rooms or data halls. Additionally, a deployment using pigtail trunks can be useful when the exact pathway or route is not fully known, avoiding exact length measurement before ordering of the assembly.

two-computer-rooms

Figure 4. MTP pigtail trunk field terminated in two computer rooms

Conclusion

Many factors should be considered to plan and install a data centre cabling infrastructure for actual and future needs, especially in high density environments. So before choose the best cabling installation solution, you need to take following points into concern:

  • Application environment: inside or between computer rooms or data halls
  • Design requirements: traditional three-layer or spine-and-leaf architecture
  • Future proofing: transition path and future-technology support

From this article, high-fibre-count MTP trunks are the best solution for your backbone cabling. MTP trunks is useful for faster installation, lower pathway congestion and greater efficiency while delivering the bandwidth to meet the needs of 40GbE/100GbE/200GbE and beyond.

How Does Fibre Optic Loss Occur?

Data transmission through fibre optic cable has many advantages over other transmission media such as copper cable or radio. Compared with other transmission media, fibre optic cable is lighter, smaller and more flexible with faster speed over long distance. However, there are some factors influencing the performance of fibre optic cable. Fibre optic loss is an important factor to be considered when selecting and installing cables. This article will introduce detailed information about fibre optic loss.

When a beam of light carrying signals travels through the core of fibre optic cable, the light will become weaker. That means the signals will be weaker. This phenomenon is called fibre optic loss or attenuation. The decrease in power level is described in dB. To transmit optical signals smoothly and safely, fibre optic loss must be decreased. Fibre optic loss is caused by internal reasons and external causes, which are also known as intrinsic fibre core attenuation and extrinsic fibre attenuation.

loss-in-fiber-optic

Intrinsic Fibre Core Attenuation

Internal fibre optic loss, also usually called intrinsic attenuation, is caused by the fibre optic cable itself. There are two causes of intrinsic attenuation. One is light absorption and the other one is scattering.

Light absorption is a major reason of fibre optic loss during optical transmission. Light is absorbed in the fibre by the materials of fibre optic cable. So light absorption is also known as material absorption. The lost power actually transferred into other forms of energy like heat because of molecular resonance and wavelength impurities. Atomic structure lies in any pure material and they absorb selective wavelengths of radiation. More over, we can’t find total pure materials in the market. So manufacturers use germanium and other materials with pure silica to optimise the fibre optic core performance.

The scattering of light is caused by molecular level irregularities in the glass structure. The light scatters in all direction. Some of them keeps traveling in the forward direction. And the light not scattered in the forward direction will be lost in the fibre optic link. Thus, to reduce fibre optic loss caused by scattering, the fibre optic core should be almost perfect and the fibre optic coating and extrusion should be carefully controlled.

Extrinsic Fibre Attenuation

Extrinsic fibre attenuation is also an important factor influencing the performance of fibre optic cable. It’s usually caused by improper handling of fibre optic cable including bend loss and splicing loss.

Bend loss is generally caused by fibre optic bend. There are two kinds of bending: micro bending and macro bending. Macro bending refers to a large bend in the fibre (with more than a 2 mm radius). To reduce fibre optic loss, you should better notice the followings:

  • Fibre core deviate from the axis;
  • Manufacturing defects;
  • Mechanical constraints during the fibre laying process;
  • Environmental variations like the change of temperature, humidity or pressure.

bend-loss

Fibre optic splicing is another cause of extrinsic fibre attenuation. It’s very common to splice fibre optic cable. So the splicing loss can’t be avoided but can be reduced with proper handling ways. For example, you can choose high quality fibre optic connectors and fusion splicing machine.

There are many factors causing fibre optic loss. To reduce the intrinsic fibre core attenuation, you should select good quality fibre optic cable. To reduce extrinsic fibre attenuation, you should better need proper handling and skills.

Maintaining MPO/MTP Polarity

The local area network (LAN) campus and building backbones as well as data centre backbones are migrating to high cabled fibre counts to meet system bandwidth needs and provide the highest connectivity density. So manufacturers start to produce MPO/MTP high density cables. Then many network designers are turning to MPO/MTP trunk cable to get the highest connectivity density for an easy migration from 10G to 40/100G. To ensure reliable system performance as well as support ease of installation, maintenance and reconfiguration, MPO/MTP cables require unique polarity design. But how to maintain proper MPO/MTP polarity?

Optical fibre links typically require two fibres to make a complete circuit. Optical transceivers have a transmit side and receive side. In any installation, it is important to ensure that the optical transmitter at one end is connected to the optical receiver at the other. This matching of the transmit signal (Tx) to the receive equipment (Rx) at both ends of the fibre optic link is referred to as polarity. In traditional cabling systems, single fibre connectors such as LC, SC are used. So it’s easy to main the polarity as long as the A side of one connector pair matches to the B side of the other connector pair in any patch cord or permanent link. However, pre-terminated, high-density cabling systems based on MPO/MTP array connectivity require a new set of design rules and have their more complicated requirements for maintaining proper polarity. Before talking about maintaining MPO/MTP polarity method, we will first introduce MPO/MTP array connectors.

MPO/MTP Array Connectors

MPO/MTP array connectors terminate multiple fibres in a single high-density interface. 4-, 6-, 8-, 12-, 24-, 36- and 72-fibre connectors are available. But 12-fibre array connectors are the most common. MPO/MTP array connectors are employed in high-density permanent link installations and can be found in pre-terminated cassettes, trunk and hydra cable assemblies used extensively in data centres.

MPO/MTP array connectors are pin and socket connectors (as shown in the following picture), requiring a male side and a female side. Cassettes and hydra cable assemblies are typically manufactured with a Male (pinned) connector. Trunk cable assemblies typically support a Female (unpinned) connector. To ensure proper end-face orientation during mating process, connectors are keyed. When the key is at the bottom, it’s called key down. When the key is on the top, it’s called key up. Under the situation of key up, the fibre holes in the connector is numbered from left to right as P1, P2… There is a white dot on one side of the connector to identify where the P1 is.

mpo-mtp-connector

Three Polarity Methods

The following will introduce three different methods to maintain polarity for systems using MPO/MTP optical connectivity. Defined by TIA/EIA-568-B.1-7, these methods include installation and polarity management practices, and provide guidance in the deployment of these types of fibre array links.

Method A

Method A employs Key Up to Key Down adapters to connect the array connectors. In this straight through configuration, Fibre 1 (P1) in the near end cassette mates to Fibre 1 (P1) in the trunk cable assembly. That is to say fibres at each end of the cable have the same position. Method A provides the simplest deployment for single-mode and multimode channels, and can easily support network extensions.

Method-A

Method B

Method B uses Key Up to Key Up Adapters. The fibre circuit is completed by utilizing straight patch cords at the beginning and end of the link, and all of the array connectors are mated Key Up to Key Up. In this method, the fibre positions are reversed. Fibre 1 is mated with fibre 12, Fibre 2 mated with Fibre 11… To ensure proper transceiver operation with this configuration, one of the cassettes needs to be physically inverted internally so Fibre 12 is mated with Fibre 1 at the end of the link. This method is more complicated than method A to manage the polarity of links. As you should identify where the actual inversions need to occur. And it also requires two separate cassettes or special labeling and management of the cassettes on one end are flipped. What’s more, this method doesn’t easily accommodate angled polished (APC) single-mode connectors.

Method-B

Method C

Method C uses Key Up to Key Down Adapters. This method uses straight patch cords and the same cassettes as in Method A. The difference is that the flip does not happen in the end patch cords but in the array cable itself. for example, Fibre 1 on one end is shifted to Fibre 2 at the other end of the cable. The Fibre 2 at one end is shifted to Fibre 1 at the opposite end etc. So it’s also complicated to properly manage the polarity of the links and to identify where the actual flipped array cord is placed in the link. Besides, it’s hard to extend the links. So this method is not suitable to be applied with emerging 40Gbps standards.

Method-C

Conclusion

There are three methods to maintain MPO/MTP polarity. Network designers should evaluate each method before implementing to ensure the reliability, ease of installation, maintenance and reconfiguration as well as easy migration to higher data rates solutions like 40/100G Ethernet. It’s recommended that a method selected should better not be changed in an installation.

Optical Fibre Selection for Network Interconnection

The emergence of Data Centres, Setorage Area Networks and other computing applications drives the needs for ultra-high speed data interconnections and structured cabling. The interconnect media choices include wireless technology, copper cable and optical fibre cable. Fibre cable offers the highest bandwidth and supports the highest data rates. There are single-mode and multimode fibre types. Different types of fibre connect with fibre optic transceivers resulting in different performances and costs. So it’s important for the network designers to understand the fibre types and select the right fibre and corresponding fibre optic transceivers for network interconnection.

Optical Fibre Types

There are three main types of optical efibre suitable for network interconnection use:
9/125μm Single-mode fibre
50/125μm multimode fibre
62.5/125μm multimode fibre

optical-fiber-types

The above numbers respectively mean the diametre of the glass core where the light travels and outside glass cladding diamere which is almost the same to most fibre types. So the difference of each fibre type is caused by the core diametre. It has great impact on system performance and system cost when balanced against network application needs. Two primary affected factors are attenuation and bandwidth.

Factors Affected by the Fibre Core Diametre

Attenuation is the reduction of signal power, or loss, as light travels through an optical fibre. Fibre attenuation is measured in decibels per kilometre (dB/km). The higher the attenuation, the higher rate of signal loss of a given fibre length. Single-mode fibres generally operate at 1310 nm (for short range) while multimode fibres operate at 850 nm or 1300 nm. Attenuation is not usually considered to be the main limiting factor in short rang transmissions. But it can cause big differences in high speed network such as 100Gb/s.

Bandwidth means the carrying capacity of fibre. For single-mode fibre, the modal dispersion can be ignored since its small core diametre. Bandwidth behavior of multimode fibres is caused by multi-modal dispersion during the light traveling along different paths in the core of the fibre. It has an influence on the system performance and data rate handling. Multimode fibre uses a graded index profile to minimize modal dispersion. This design maximizes bandwidth while maintaining larger core diametres for simplified assembly, connectivity and low cost. So manufacturers start to develop higher-performance multimode fibre systems with higher bandwidth.

System Costs: Single-mode and Multimode Fibres

A fibre optic transceiver usually consists the optical light sources, typically LED–light emitting diode and optical receivers. Since the core diametre size and primary operating wavelengths of single-mode fibre and multimode fibre are different, the associated transceiver technology and connectivity will also be different. So is the system cost.

To utilize the single-mode fibres generally for long distance applications (multi-kilometre reach), transceivers with lasers such as SFPP-10GE-LR (an SFP+ 1310nm 10 km transceiver supporting single-mode fibres) that operate at longer wavelengths with smaller spot-size and narrower spectral width. But these kinds of transceivers need higher precision alignment and tighter connector tolerance to smaller core diametres. Thus, it causes higher costs for single-mode fibre interconnections. To lower the cost, manufacturers produce transceivers based on VCSEL (vertical cavity surface emitting laser), for example, 10G-SFPP-SR (an SFP+ 850nm 300m transceiver supporting multimode fibres), which are optimised for use with multimode fibres. Transceivers applying low cost VCSEL technology to develop for 50/125μm multimode fibres, take advantage of the larger core diametre to gain high coupling efficiency and wider geometrical tolerances. OM3 and OM4 multimode fibres offer high bandwidth to support data rates from 10Mb/s to 100Gb/s.

Conclusion

Optical fibre is an easily-installed medium that is immune to electromagnetic interface and is also more efficient in terms of power consumption. What’s more, fibre optic cable can save space and cost with higher cabling density and port density over copper cabling. For single-mode fibre and multimode fibre, each one has its advantages and disadvantages. Network designers should better select the right fibre type and related fibre optic transceivers according to specific situations for higher system performance. Of course, cost is another important factor to be considered.

What Should We Know Before Deploying 10 Gigabit Ethernet Cable?

Since the need for high data speed increases and the price of optical equipment becomes more affordable, many enterprises start to deploy 10 Gigabit Ethernet cables in their cooperate backbone, data centres to support high-bandwidth applications. But what should we know before deploying 10 Gigabit Ethernet cables?

Fibre Choices for Deploying 10 Gigabit Ethernet Cable

Three factors should be considered for fibre cable deployment: fibre cable type, 10 Gigabit Ethernet physical interface and fibre optical transceiver module. The following tables show the standard fibre cables, physical interfaces, and transceiver module applicable to 10 Gigabit Ethernet.

Fibre Cables Multimode OM1 fibre (62.5/125 μm)
OM2 fibre (50/125 μm)
OM3 fibre (50/125 μm)
Single mode 9/125 μm fibre
Physical Interfaces 10GBase-LRM Max distance 220m
10GBase-S Max distance 300m
10GBase-L Max distance 10km
10GBase-E Max distance 40km
10GBase-Z Max distance 80km
Transceiver modules XENPACK Large form factor
X2 Smaller than XENPACK
XFP Smaller than X2
SFP+ Smallest form factor

Note: the 10 Gigabit Ethernet physical interface type should be the same on both ends of the fibre link. For example, it is OK to deploy a fibre link with one XFP-10G-MM-SR optics on the left, and one SFP-10G-SR optics on the right. However, one SFP-10G-SR optics and one SFP-10G-LRM optics can’t connect together because of different physical types.

Copper Choice for Deploying 10 Gigabit Ethernet Cable

As switching standards copper cabling standards develop, copper cabling for 10GbE is more widely used. There are three different copper technologies for deploying 10 Gigabit Ethernet cables. Each one has different performances and prices.

First, 10GBase-CX4 is the first 10 Gigabit Ethernet copper cable standard. It’s relatively economical and allows for very low latency. But the form factor is too large for high density port counts in aggregation switches.

Second, Small Form-factor Plus (SFP+) is the latest standard for optical transceivers. 10 Gb SFP+Cu Direct attach cables (DAC) directly connect into an SFP+ housing. It’s the best copper solution for servers and storage devices because it has low latency, small form factor and reasonable price.

Third, 10GBase-T is a fully IEEE compliant Ethernet transport technology standard, as defined by IEEE 802.3an-2006. 10GBase-T is to run 10 Gigabit Ethernet over CAT6a and CAT7 copper cabling up to 100 metres. 10GBase-T copper twisted-pair cabling can enable the earlier 10MB, 100MB and 1GB operation. However, 10GBase-T still needs to be improved on its price, power consumption and latency.

Media Copper cable Range (max) Average Latency
CX4 Twinax 15m (49ft) 0.1 μs
SFP+ DAC Twinax SFP+CU 10m (33ft) 0.1 μs
10GBase-T CAT6 RJ45 30m(98ft)—50m (164ft) >1.5 μs
CAT6a RJ45 100m (98ft) >1 μs
CAT7 GG45 100m (98ft) >1 μs
SFP+ Direct Attach Cables

SFP+ DAC cable integrates SFP+ compatible connectors with a copper cable into a low-latency, energy-efficient, and low-cost solution. SFP+ direct attach cables offer the smallest 10 Gigabit form factor and a small cable diametre for higher density and optimised rack space in 10 Gigabit Ethernet (GbE) uplinks and 10 Gigabit Fibre Channel SAN and NAS input/output connections. To use SFP+ direct attach cables can save you a lot compared with fibre optic solutions. And it can still provide lower latency and save up to 50% power consumption per port than other copper twisted-pair cabling systems.

sfp+ dac

SFP+ direct attach cables can also provide enhanced scalability and flexibility. The cables connect several servers or storage devices together in a single rack. Thus, it reduces the use of intermediate patch panels. And it’s easy to move racks or deploy one rack at a time since the cabling outside of the rack is limited to the main switch connection.

FS offers comprehensive solutions for 10 Gigabit Ethernet cabling, including fibre cables, copper cables, and SFP+ direct attach cables and each one has various subcategories. Before deploying 10 Gigabit Ethernet cables, you need to consider factors of the performance, cost, power consumption and latency and choose the most suitable cabling solution.

Related Article: Cisco SFP-10G-SR: All You Need to Know

Brief Introduction for 10 Gigabit Ethernet

The demand for high bandwidth promotes the development of data transmission technology. Ethernet standard continuously evolves to meet fast speed need, from 100BASE, 1000BASE to 10 Gigabit Ethernet. Meanwhile, the data carrying technology also develops to provide great bandwidth for transporting data with low cost, such as the copper and fibre cable as well as optical transceiver module.

10 Gigabit Ethernet CablingFigure1. 10 Gigabit Ethernet Cabling

Media for 10 Gigabit Ethernet: Copper and Fibre

In 10 Gigabit Ethernet, copper and fibre are used to transport data. Each one has its own advantages and disadvantages.

Copper is more affordable and easy to install. It acts the best when used in short lengths, typically 100 meters or less. But when deployed over long distance, electromagnetic signal characteristics will influence its performance. Besides, bundling copper cabling can cause interference, which makes it difficult to employ as a comprehensive backbone. So copper cabling are widely used in PCs and LANs communication network instead of campus or long-distance transmission.

Compared with copper, fibre cabling is usually used for long distance communication among campus, and environments that need protection from interference, such as manufacturing areas. In addition, fibre cabling is more reliable and less susceptible to attenuation, which makes it suitable for data transmission distance over 100 meters. But fibre still has drawbacks. It’s more costly than copper.

The Evolution of 10 Gigabit Ethernet Cabling

Since 10 GbE technologies have changed, so have the cabling technologies. There are two main standards: IEEE802.3ae and IEEE802.3ak. Factors covered in these standards like transmission distance and equipment being used are helpful to determine the cabling strategy.

  • IEEE802.3ae

IEEE802.3ae standard updates the existing IEEE802.3 standard for 10GbE fibre transmission. The new standard defines several new media types for LAN, metropolitan area network (MAN) and wide area network (WAN) connectivity.

10GBASE-SR – it supports 10GbE transmission over standard multimode fibre (850 nm) for distances of 33 and 86 meters. The SR standard also supports up to 300 meters using the new 2000MHz/km multimode fibre (laser optimized). This one is the lowest-cost optics for 10GbE.

10GBASE-LR – it uses optics (1310nm) and supports single-mode fibre up to 10 km.

10GBASE-LX4 – it can support multimode fibre for distances up to 300 meters using Coarse Wavelength Division Multiplexing (CWDM). The LX4 standard also supports single mode fibre for up to 10 Km. LX4 is more expensive than both SR and LR because it requires four times the optical and electrical circuitry in addition to optical multiplexers.

10GBASE-ER – it uses optics (1550nm) to support single mode fibre up to 30 km.

  • IEEE802.3ak / 10GBASE-T

10GBASE-T is the latest proposed 10GbE standard for use with unshielded twisted-pair (UTP) style cabling. This standard is to improve the performance and increase the transmission distance at a lower cost. Category 5 (Cat 5) and Category 6 (Cat 6) are the most common cabling systems being installed today. But Cat 5 can’t meet the bandwidth demands of 10GbE’s transmission. To meet the needs of 10GbE, manufacturers create Category 6A (Cat 6A), designed with existing Cat 6 cable but measured and specified to higher frequencies. In addition to Cat 6A, 10GBASE-T will operate on Category 7 (Cat 7) cables.

10GbE Transceivers

Except the cabling, transceivers also need to be considered for the network connectivity. Transceivers provide the interface between the equipment sending and receiving data. 10GbE has four defined transceiver types, including XENPAK, X2, XFP and SFP+ (Small Form-factor Pluggable Plus). These transceivers are pluggable and are compliant with 802.3ae standard.

Among them, SFP+ is the smallest 10G form factor. And it can interoperate with XENPAK, X2, XFP interface on the same link. Fiberstore provides a number of interfaces attempted to satisfy different objectives including support for MMF and SMF compatibility, such as SFP-10G-SR, SFP-10G-LR, SFP-10G-ER, SFP-10G-ZR, etc. For example, SFP-10G-SR transceiver module can support 300 meters data transmission distance over 850 nm multimode fibre. And SFP-10G-LR module supports the link length up to 10 kilometers over 1310 nm single mode fibre.

10 Gigabit Ethernet Transceiver

Figure2. 10 Gigabit Ethernet Transceiver

As the corresponding cabling technology gets great improvement, 10 Gigabit Ethernet is becoming more affordable and pervasive. 10G network brings us higher speed. For 10G network connectivity, SFP+ transceivers are recommended to transport data over copper or fibre cabling.

Related Article: Cisco SFP-10G-SR: All You Need to Know