SMF or MMF, Which to Choose for Date Center Cabling?

It is critically important to choose the suitable cabling plant for data center connectivity, because the wrong decision may leave a data center incapable of supporting future grown, requiring an extremely costly optical cable plant upgrade to move to higher speeds. In the past, multimode fiber (MMF) has been widely deployed in data center for many years because of the high cost of single mode fiber (SMF). However, the price difference between SMF and MMF has been largely negated as technologies have evolved. With cost no longer the dominant decision criterion, operators can make architectural decisions based on performance. So SMF or MMF, which should be chosen for data center cabling? Keep reading and you’ll find the answer.

MMF – Unable to Reach the Distance Need

Many data center operators who deployed MMF OM1/OM2 fiber a few years ago are now realizing that these MMF cannot support higher transmit rates like 40 GbE and 100 GbE. So some MMF users have been forced to add later-generation OM3 and OM4 fiber to support standards-based 40GbE and 100GbE interfaces. But the physical limitations of MMF mean that the distance between connections must decrease when data traffic grows and interconnectivity speeds increase. Deploying more fibers in parallel to support more traffic is the only alternative. So the limitations of MMF have become more serious when it has been widely deployed for generations. The operators must weigh unexpected cabling costs against a network incapable of supporting new devices.

MMF

SMF – A Viable Alternative

Due to the cost of the pluggable optics required, previously organizations were reluctant to implement SMF inside the data center, especially compared to MMF. However, newer silicon technologies and manufacturing innovations are driving down the cost of SMF pluggable optics. Fiber optic transceivers with Fabry-Perot edge emitting lasers (single-mode) are now comparable in price than power dissipation to VCSEL (multimode) transceivers. Moreover, SMF eliminates network bandwidth constraints, where MMF cable plants introduce a capacity-reach tradeoff. This allows operators to take advantage of higher-bit-rate interfaces and wave division multiplexing (WDM) technology to increase by three orders of magnitude the amount of traffic that the fiber plant can support over longer distances. All these factors make SMF a more viable option for high-speed deployment in data center.

SMF

Comparison Between SMF and MMF

With 40 GbE and 100 GbE playing roles in some high-bandwidth applications, 10 GbE has become the predominant interconnectivity interface in large data centers. Put it simply, the necessity for fiber cabling supporting higher bit rates over extended distances is here today. With that in mind, the most significant difference between SMF and MMF is that SMF provides a higher spectral efficiency than MMF. It means that SMF supports more traffic over a single fiber using more channels at higher speeds. This is in stark contrast to MMF, where cabling support for higher bit rates is limited by its large core size. As a matter of fact, in most cases, currently deployed MMF cabling is unable to support higher speeds over the same distance as lower-speed signals.

Summary

The tradeoff between capacity and reach is important as operators consider their cabling options. Network operators need to assess the extend to which they believe their data centers are going to grow. For environments where users, applications, and corresponding workload are all increasing, SMF offers the best future proofing for performance and scalability. And because of fundamental changes in how transceivers are manufactured, those benefits can be attained at prices comparable to SMF’s lower performing alternative.

40G Fanout Solution for Data Center

With the requirement of high-speed Ethernet in data center, the migration from 10G to 40G is beginning. Fanout technology has been widely applied in 40G data center to get higher data rate and higher port density. The principle of fanout technology is just like the water pipeline in a building. Water is transferred from the trunk pipeline, and then trunk pipeline fans out into several pipelines that have smaller diameters to bring the water to every house.

A device needing to be connected to two or several devices with different physical interface is very common. So the superiority of fanout technology is brought into full play, especially in the distribution layer of 40G data center and adapting lower data rate to 40G in cabling. Several widely used fanout/breakout assemblies in 40G data center will be introduced in this article.

40G MPO Fanout Cables

A MPO fanout cable is a multi-fiber optical cable containing several individual tight buffered optical fibers with one end terminated with a male or female MPO connector and the other end usually terminated with several LC connectors.

MPO fanout cable

Figure 1

Various MPO fanout cables are available in the market now. The fanout/breakout cable which is able to fan out into 12 or 24 fibers is most commonly used in 40G cabling deployment.

Figure 1 shows a typical 12-fiber MPO breakout cable (also called MPO harness cable) with OM3 optical fiber as the transmission media. This 12-fiber MPO fanout cable is terminated with a male MPO connector on one end and 6 duplex LC connectors on the other end. It can work from MPO trunk backbone assemblies to LC fiber rack system in high density backbone cabling from 40G device to 10G devices.

There is also a little bit smaller MPO fanout cable, of which the fibers fan out directly from the MPO connectors. This mini MPO harness cable can be easily put into patch panel and increase the cabling density effectively (see Figure 2).

MPO cassette

Figure 2

MPO cassette is another special type of MPO fanout cable. It is designed for those who want to have everything in neat and tidy. The MPO cassette breaks the traditional design of the fanout cable. It can offer better cable protection and management by housing one or several mini size MPO fanout cables in a cassette. For a 12-fiber MPO cassette, there will be a 12-fiber mini direct fanout MPO cable inside the cassette. With one MPO in the back side of the cassette and six duplex LC connectors in the front (see Figure 3).

This type of cassette can be installed in the standard rack in data center. To achieve higher cable density, more 12-fiber or 24-fiber mini MPO fanout cables are installed for 40G transmission. For instance, Figure 3 is a 24-fiber MPO cassette containing two 12-fiber fanout cables, thus there are two 12-fiber MPO connectors on the cassette. A 24-fiber MPO cassette can also have a mini size 24-fiber fanout cable inside the cassette. This cassette will only have one 24-fiber MPO connector in the back side. No matter what the fiber count and connector type are, these MPO cassettes can be customized in Fiberstore according to your requirements.

24 fiber cassette

Figure 3

40G Fanout Direct Attach Cable

By offering direct interconnection for devices in data center, direct attach cable also has fanout design. Converting one form factor to a different form factor is necessary in many cases. For instance, a 40G device may be connected to one or several 10G devices for distribution or adapting. With fanout direct attach cable, this process would be much easier. This pre-terminated components can also increase the reliability of data center effectively.

A 40G direct attach cable usually has a 40G QSFP+ connector on one end, no matter it uses copper or fiber as the transmission media. And four 10G XFP connectors or four 10G SFP+ connectors are terminated on the other end of the 40G direct attach cable.

QSFP-8LC AOC

Figure 4

Sometimes it also needs to convert QSFP+ to LC interface. There is also another type of 40G DAC can satisfy this requirement. This kind of DAC is attached with a QSFP+ on one end and several LC connectors on the other end (see Figure 4). Figure 4 shows an active optical cable (AOC) with one end plugged into a QSFP+ switch and the other end attached with four duplex LC connectors which are separately linked to four 10G SFP+ transceivers. These 10G transceivers are then plugged into 10G switch with SFP+ ports. In this way, 40G cabling to 10G cabling is achieved.

Conclusion

Fanout technology is playing an important role in 40G data center. Products like 40G break out cable, cassette and 40G break out direct attached cable can all be found and customized in Fiberstore. Different connectors, cable length, fiber count etc. can all be specially designed according to your application. Please contact sales@fs.com for more details about fanout products in 40G data center.

Things You Should Know about Fiber Optic Connector Polishing

Optical fiber is utilized for high-speed and error-free data transmission across connector assemblies. So the connector end faces need to be polished to optimize performance. And also the connectors must follow acceptance criteria related to insertion and back reflection loss as well as end-face geometry specifications. This article will talk about the fiber optic connectors polishing.

Polishing Process

Early physical contact connectors required spherical forming of their flat end faces as part of the polishing procedure. It involved a four-step process: epoxy removal, ferrule forming, and preliminary and final polishing. These steps utilized aggressive materials for epoxy removal and ferrule forming, generally accomplished with diamond polishing films. Now the polishing process has developed into a sequence of epoxy removal, followed by rough, intermediate and final polishing cycles because almost all connectors are manufactured with a pre-radiused end face. One goal is to avoid excessive disruption of the spherical surface, while still producing a good mating surface.

Polishing Specifications

Polishing specifications for fiber connectors fall into two categories related to performance and end-face geometry. Back reflection and insertion loss specifications are the most critical measures of polished end functionality. The insertion loss is the amount of optical power lost at the interface between the connectors caused by fiber misalignment, separation between connections (the air gap) and the finish quality of each connector end. The current standard loss specification is less than 0.5 dB, but less than 0.3 dB is increasingly specified. Back reflection is the light reflected back through the fiber toward the source. High back reflection can translate to signal distortion and, therefore, bit errors in systems with high data transfer rates.

Polishing Material

Today several types of connectorized fibers are available, the most common of which are 2.5 mm, 1.25 mm and multifiber. Connector end faces must first be air-polished to ensure a proper mating surface. This will be followed by a sequence of polishing steps depending on the type of connector, the back reflection and the insertion loss specifications. Regardless of the connector type, most polishing sequences begin with aggressive materials, including silicon carbide to remove epoxy and diamond lapping films for beginning and intermediate polishing. These remove both surrounding material and fiber at the same rate. But the last polishing step needs a less aggressive material to attack only the fiber, such as silicon dioxide. Using a material for final polishing that is too aggressive could result in excessive undercut. The wrong final-polish material can cause excessive protrusion, leading to fiber chipping and cracking during the connector mating process.

Impact Factor

Issues to be examined include the polishing films used, the type of epoxy and lubrication. Films are the most significant impact because the gradations and quality vary from supplier to supplier. End users should pay attention on selecting film type. Excessively aggressive films can destroy a 125-μm fiber and the end-face radius. Epoxy removal is also essential to contamination-free polishing. Some types of epoxies can be removed more easily with specific grades of silicon-carbide polishing films. The films to use in this step depend on the size of the epoxy bead mounted on the connector end face and the epoxy type. Epoxies have different varieties. Some will be tacky, some firm. In all, a contamination-free environment is essential to optimizing connector polishing.

Polishing may be an old art form, but for the immediate future, it’s here to stay. Undoubtedly inspection criteria will increase. Polishing procedures will be driven to change, and new connector style will also make us continuously strive to reinvent our approach to polishing. Fiberstore has various products about fiber optic polishing. For more details, please visit FS.COM.

Evolution of Flat, PC, UPC and APC Fiber Connectors

When a connector is installed on the fiber end, loss will be incurred. Some light loss would be reflected back directly down the fiber towards the light source that generated it. These back reflections, or Optical Return Loss (ORL) will damage the laser light sources and also disrupt the transmitted signal. Fiber connectors with different polishing types have different back reflections (see the picture below). With the development of technology, four polishing types are available: flat-surface, Physical Contact (PC), Ultra Physical Contact (UPC), and Angled Physical Contact (APC). How one evolves into another? This article will tell the answer.

polishing type

Flat Fiber Connector

The original fiber connector is a flat-surface connection, or a flat fiber connector. The primary issue of it is that a small air gap between the two ferrules is naturally left when mated. This is partly because the relatively large end-face of the connector allows for numerous slight but significant imperfections to gather on the surface. The flat fiber connector is not suitable for single-mode fiber cables with a 9µm core size, thus it is essential to evolve into Physical Contact (PC) connectors.

flat fiber connector

PC Fiber Connector

The Physical Contact is polished with a slight spherical design to reduce the overall size of the end-face, which helps to decrease the air gap issue faced by Flat Fiber connectors. It results in lower Optical Return Loss (ORL) with less light being sent back towards the power source.

PC connector

UPC Fiber Connector

Building on the convex end-face attributes of the PC, but utilizing an extended polishing method creates an even finer fiber surface finish: Ultra Physical Contact (UPC) connector. It has a lower back reflection (ORL) than a standard PC connector and allows more reliable signals in digital TV, telephony and data systems. UPC fiber connector could be used with both single-mode fiber and multimode fiber. Usually the UPC single-mode fiber connector is blue, but the UPC multimode fiber connector is beige. (Note: 10G UPC multimode fiber connector is aqua.)

UPC connector

PC and UPC connectors do have a low insertion loss, but the back reflection (ORL) depends on the the surface finish of the fiber. The finer the fiber grain structure, the lower the back reflection. When PC and UPC connectors are continually mated and unmated, the back reflection will begin to degrade. So there is a need for a connector with low back reflection and it could sustain repeated matings/unmatings without ORL degradation.

APC Fiber Connector

The end faces of Angled Physical Contact connectors are still curved but are angled at an industry standard eight degrees, which allows for even tighter connections and smaller end-face radii. Combined with that, any light that is redirected back towards the source is actually reflected out into the fiber cladding, again by the virtue of the 8°angled end-face. APC connector back reflection does not degrade with repeated matings/unmatings. APC fiber connector can only be used with single-mode fiber and it is green.

APC connector

It is clear that all of the connector end-face options mentioned above take a place in the market. And it is hard to claim that one connector beats the others when your specification needs to consider cost and simplicity not just optical performance. Your particular need decides which one to choose. For those applications calling for high precision optical fiber signaling, APC should be the first consideration, but less sensitive digital systems will perform equally well using UPC. For various connector options, please visit FS.COM.

Related Article: Differences between CWDM and DWDM
How Many Fiber Connector Type Do You Know?

A Guide to Fiber Optic Splicing

Fiber Optic Splicing Basis

It is vital for any company or fiber optic technician involved in telecommunications to grasp knowledge of fiber optic splicing methods. Fiber optic splicing refers to joining two fiber optic cables together. It can result in lower light loss and back reflection. Two methods of fiber optic splicing are available: fusion splicing and mechanical splicing. Which technique best fits your economic and performance objectives? Keep reading the following statement and find the answer.

Fusion Splicing vs. Mechanical Splicing

Fusion splicing is an optical junction of two optical fibers by permanently welding them together with heat generated by an electronic arc (called arc fusion). It is the most widely used method of splicing because it provides least reflectance and lowest loss, as well as providing the strongest and most reliable joint between two fibers.

fusion splicing

Fusion splicing steps:

  1. Prepare the fiber: strip the protective coatings, jackets, tubes, strength members, and leave only the bare fiber showing. Pay attention to cleanliness.
  2. Cleave the fiber: using a good fiber optic cleaver here is essential to a successful fusion splice. The cleaved end must be mirror-smooth and perpendicular to the fiber axis to obtain a proper splice.
  3. Fuse the fiber: alignment and heating are the two steps within this step. Alignment can be automatic or manual depending upon the equipment you have. Once the fusion splicer unit are properly aligned, then you can use an electrical arc to melt the fibers and permanently weld the two fiber ends together.
  4. Protect the fiber: protecting the fiber from bending and tensile forces will ensure the splice not break during normal handling. Using heat shrink tubing, silicone gel and/or mechanical crimp protectors will keep the splice protected from outside elements and breakage.

Aligning and holding in place by a self-contained assembly, a mechanical splice is a junction of two or more optical fibers. Not permanently joined, the fibers are just precisely held together so that light can pass from one to another.

mechanical splicing

Mechanical splicing steps:

  1. Prepare the fiber: same with the step of fusion splicing.
  2. Cleave the fiber: the process is identical to the cleaving for fusion splicing.
  3. Mechanically join the fibers: simply position the fiber ends together inside the mechanical splice unit. The index matching gel inside the mechanical splice apparatus will help couple the light from one fiber end to the other.
  4. Protect the fiber: the completed mechanical splice will provide its own protection for the splice.
Tips for Better Splicing
  1. Clean your splicing tools thoroughly and frequently.
  2. Operate and maintain your cleaver properly.
  3. For fusion splicing, the fusion parameters must be adjusted minimally and methodically.
Which Method Is Better?

Cost and performance are the two deciding factors for choosing one method over the other. Mechanical splicing has a low initial investment ($1,000 – $2,000) but costs more per splice ($12-$40 each). Fusion splicing has lower cost per splice ($0.50 – $1.50 each) but higher initial investment ($15,000 – $50,000). As for the performance, fusion splicing produces lower loss and less back reflection than mechanical splicing. Fusion splices are primarily used with single-mode fiber, while mechanical splices work with both single-mode and multimode fiber.

Conclusion

To sum up, the two fiber optic splicing methods have its own advantages. Fusion splicing is invested for long haul single-mode networks, while mechanical splicing is used for shorter local cable runs. For better fiber optic splicing, besides the above splicing steps, high-quality fiber optic splicing tools are also essential, such as fusion splicers, fiber optic cleavers, etc. After all, good methods and excellent tools will produce the best performance.

Why Is Fiber Cleaning Necessary?

At a BICSI Conference in 2008, JDSU stated, “Contamination is the number-one reason for troubleshooting optical networks.” For the long-term reliability of any network, fiber cleaning is critical and it is at the heart of the profitability of successful fiber deployment. This paper will introduce the necessity of fiber cleaning and then give two tips on fiber protection against dust contamination.

Four reasons for fiber cleaning are listed below:

Signal Failure

As you know, fiber optic networks work by carrying pulses of light between transmitters and receivers. Contamination and dirt will block the signal and lead to light loss, reducing power and efficiency. The amount of light loss shrinks correspondingly as links carry higher data rates, which makes cleaning even more essential. Dirty equipment can give rise to network failure or paralysis.

Equipment Failure

Dirt can cause permanent damage to the end-face, digging into the surface and creating pits that increase back reflection. Failures in the network caused by dirt can increase costs and install time because damaged equipment may need to be tracked down and replaced, which means more time on-site and greater expenditure. Both of the two will impact the overall budget for a deployment.

Angry Occupants

It is naturally going to enrage consumers and building owners by leaving a mess in a subscriber’s home or the common areas of an apartment building. They’d like to have the benefits of fiber broadband rather than the dirt or damage to their property when it is installed.

Adopting Proper Cleanliness Procedures

While it is easy to focus on more visible debris, dirt is most dangerous at a microscopic level, particularly when it comes to the end-faces of connectors. For example, simply touching the ferrules of a connector will deposit significant amounts of body oil onto the end face. Best practice for this issue is to use high-grade, completely lint-free wipes (aiming for clean room quality) and pure Isopropyl Alcohol (IPA).

On top of this, here are two areas to keep an especially close eye on:

Mating and Unmating

The actual process of mating and unmating connectors can also cause damage to the ceramic. Therefore, aim to minimize this plugging and unplugging as much as possible and ensure you inspect the two end-faces for dirt or debris that could be crushed between them. This can cause permanent damage, such as scratches, cracks or pits that will require re-termination, not just cleaning. Moreover, make sure you inspect any other equipment ports that the connector is being plugged into, as they can also harbour contamination.

Don’t Rely on Dust Caps

Many people may think that if you don’t take the dust cap off your factory terminated connector until you plug it in, it’ll keep dirt free. After all, it was packaged in a sterile factory environment. In fact, dust caps are preventing damage to the end-face, rather than stopping all contamination reaching the connector.

FS.COM Fiber Cleaning Solution

As a professional supplier in the optical industry, FS.COM has various high-quality and low-price fiber optic cleaning tools, such as fiber connector cleaner, optical connector cleaning cards, one push fiber optic cleaner for 1.25mm connectors, etc. These tools can help to ease or remove all kinds of dirty particles, such as dust, dripping and moist. Choosing any kind of fiber optic cleaning tools in FS.COM will give you a surprise!

Data Center 10 Gigabit Ethernet Cabling Options

With the dramatic growth in data center throughput, the usage and demand for higher-performance servers, storage and interconnects have also increased. As a result, the expansion of higher speed Ethernet solutions, especially 10 and 40 Gigabit Ethernet has been ongoing. For 10 Gigabit Ethernet solution, selecting the appropriate 10-gigabit physical media is a challenge, because 10GbE is offered in two broad categories: optical and copper. This article will introduce both optical and copper cabling options for 10 Gigabit Ethernet.

Fiber Optic Cables

Two general types of fiber optic cables are available: single-mode fiber and multimode fiber.

Single-mode Fiber (SMF), typically with an optical core of approximately 9 μm (microns), has lower modal dispersion than multimode fiber. It is able to support distances of at least 10 kilometers, depending on transmission speed, transceivers and the buffer credits allocated in the switches.

Multimode Fiber (MMF), with an optical core of either 50 μm or 62.5 μm, can support distances up to 600 meters, depending on transmission speed and transceivers.

When planning data center cabling requirements, be sure to consider that a service life of 15-20 years can be expected for fiber optic cabling. Thus the cable chosen should support legacy, current and emerging data rates.

10GBASE-SR — a port type for multimode fiber, 10GBASE-SR cable is the most common type for fiber optic 10GbE cable. It is able to support an SFP+ connector with an optical transceiver rated for 10GbE transmission speed. 10GBASE-SR cable is known as “short reach” fiber optic cable.

10GBASE-LR — a port type for single-mode fiber, 10GBASE-LR cable is the “long reach” fiber optic cable. It is able to support a link length of 10 kilometers.

OM3 and OM4 are multimode cables that are “laser optimized” and support 10GbE applications. The transmission distance can be up to 300 m and 400 m respectively.

Copper Cables

Common forms of 10GbE copper cables are as follows:

10GBASE-CR — the most common type of copper 10GbE cable, 10GBASE-CR cable uses an attached SFP+ connector and it is also known as a SFP+ Direct Attach Copper (DAC). This fits into the same form factor connector and housing as the fiber optic cables with SFP+ connectors. Many 10GbE switches accept cables with SFP+ connectors, which support both copper and fiber optic cables.

Passive and Active DAC — passive copper connections are common with many interfaces. As the transfer rates increase, passive copper does not provide the distance needed and takes up too much physical space. So the industry is moving towards an active copper type of interface for higher speed connections. Active copper connections include components that boost the signal, reduce the noise and work with smaller gauge cables, improving signal distance, cable flexibility and airflow.

10GBASE-T — 10GBASE-T cables are Cat6a (category 6 augmented). Supporting the higher frequencies required for 10GbE transmission, category 6a is required to reach the distance of 100 meters (330 feet). Cables must be certified to at least 500 MHz to ensure 10GBASE-T compliance. Cat 6 cables may work in 10GBASE-T deployments up to 55 meters (180 feet) depending on the quality of installation. Some 10GbE switches support 10GBASE-T (RJ45) connectors.

When to Use Different Type of 10GbE Cables

To summarize, currently the most common types of 10GbE cables use SFP+ connectors.

  • For short distances, such as within a rack or to a nearby rack, use DAC with SFP+ connectors, also known as 10GBASE-CR.
  • For mid-range distances, use laser optimized multimode fiber cables, either OM3 or OM4, with SFP+ connectors.
  • For long-range distances, use single-mode fiber optic cables, also known as 10GBASE-LR.

How to Achieve a Reliable, Affordable and Simple 10 Gigabit Ethernet Deployment?

10 Gigabit Ethernet, or 10GE and 10GbE, is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. Nowadays, 10 Gigabit Ethernet is gaining broader deployments by the increasing bandwidth requirements and the growth of enterprise applications. But there is a question to be considered when deploying 10 Gigabit Ethernet — how to achieve a reliable, affordable and simple 10 Gigabit Ethernet deployment? The text below will tell the answer.

10 Gigabit Ethernet and the Server Edge: Better Efficiency

Server virtualization supports several applications and operating systems on a single server by defining multiple virtual machines on the server. Virtual machines grow and require larger amounts of storage than one physical server can provide. Storage area networks (SANs) or network attached storage (NAS) provide additional and dedicated storage for virtual machines. But connectivity between the servers and storage must be fast to avoid bottlenecks. 10 Gigabit Ethernet is able to provide fastest interconnectivity for virtualized environments.

10 Gigabit Ethernet SAN versus Fibre Channel: Simpler and More Cost-effective

The Internet Small Computer System Interface (iSCSI), an extension of SCSI protocol used for block transfers in most storage devices and Fibre Channel, is making 10 Gigabit Ethernet an attractive, alternative interconnect fabric for SAN applications. The iSCSI capabilities allow 10 Gigabit Ethernet to compare very favorably to Fibre Channel as a SAN interconnect fabric. 10GbE networking can reduce equipment and management costs as its components are less expensive than highly specialized Fibre Channel components and do not require a specialized skill set for installation and management.

10 Gigabit Ethernet and the Aggregation Layer: Reduce Bottlenecks

10 Gigabit Ethernet allows the aggregation layer to scale to meet the increasing demands of users and applications. It can help bring oversubscription ratios back in line with network-design best practices, and provides some important advantages over aggregating multiple Gigabit Ethernet link, such as less fiber usage, greater support for large streams and longer deployment lifetimes.

10 Gigabit Ethernet and Fiber Cabling Choices

For any fiber cable deployment, the types of fiber cable, 10 Gigabit Ethernet physical interface and optics module form factor need to be considered. Form factor options are interoperable as long as the 10 Gigabit Ethernet physical interface type is the same on both ends of the fiber link.

10 Gigabit Ethernet and Copper Cabling Choices

Currently, three different copper cabling technologies for 10 Gigabit Ethernet are available. 10GBASE-CX4 was the first 10 Gigabit Ethernet copper standard. CX4 was relatively economical and allowed for very low latency. Its disadvantage was a too-large form factor for high density port counts in aggregation switches. SFP+ direct attach cables (DAC) connect directly into an SFP+ housing. It has become the connectivity of choice for servers and storage devices in a rack due to its low latency, small form factor and reasonable cost. 10GBASE-T is able to run 10 Gigabit Ethernet over CAT6a and CAT7 copper cabling up to 100 meters, but it needs technology improvements to lower its cost, power consumption and latency.

10 Gigabit Ethernet and the SFP+ Makeover: Direct Attach Cables are convenient for Short Runs

SFP+ direct attach cables integrate SFP+ connectors with a copper cable into a low-latency, energy-efficient, and low-cost solution. Direct attach cables are currently the best cabling option for short 10 Gigabit Ethernet connections.

10 Gigabit Ethernet and Link Aggregation Offers Redundancy and Resiliency

The Link Aggregation Control Protocol (LACP) standard defines a way of bundling several physical ports over one logical channel. From a deployment standpoint, it is far easier to implement a distributed LACP solution with stackable switches that allow link aggregation across the stack. In this configuration, the stack acts as a single logical switch and link aggregation is seamless.

10 Gigabit Ethernet and Top-of-Rack Best Practice

The diagram below shows a stackable 10 Gigabit Ethernet ToR switching solution enabling cost-effective SAN connectivity for servers and network storage. In addition to better performance, LACP functionality provides better availability and redundancy for servers and storage. Moreover, it provides failover protection if one physical link goes down, while iSCSI traffic load balancing ensures greater transmission throughput with lower latency.

10GbE ToR switching solution

10 Gigabit Ethernet and Distribution Layer Best Practice

The diagram below shows Gigabit access switches with 10 Gigabit uplinks and stackable 10 Gigabit aggregation switches. At the edge, stacks of access switches are virtualized into a single switch, reducing configuration and management overhead.

Gigabit access switches

To achieve a reliable, affordable and simple 10 Gigabit Ethernet deployment, the factors stated above need to be considered. Fiberstore SFP+ transceivers and SFP+ direct attach cables are ideal for cost-sensitive organizations considering 10 Gigabit Ethernet applications and they help growing companies support rising bandwidth requirements, new applications, and the demands of a fast-paced business environment.

Fiberstore Passive Optical Components Solution

Passive optical components market is propelled by the accelerating bandwidth requirements coupled with the growth of passive optical network (PON). Usage of passive optical components to obtain energy efficient network solutions is gaining popularity. This article will introduce some Fiberstore passive optical components.

Optical Attenuators: an optical attenuator is a device that is used to reduce the power level of an optical signal. Optical attenuators are commonly used in fiber optic communications, either to test power level margins by temporarily adding a calibrated amount of signal loss, or installed permanently to properly match transmitter and receiver levels.

optical attenuators

Optical Circulator: an optical circulator is a multi-port (minimum three ports) non-reciprocal passive component. The function of an optical circulator is similar to that of a microwave circulator — to transmit a light wave from one port to the next sequential port with a maximum intensity, but at the same time to block any light transmission from one port to the previous port.

optical circulator

Fiber Collimator: a fiber collimator is a device for collimating the light coming from a fiber, or for launching collimated light into the fiber. It is used to expand and collimate the output light at the fiber end, or to couple light beams between two fibers. Both single-mode fiber collimators and multimode fiber collimators are available.

fiber collimator

Optical Isolator: an optical isolator is a passive optical component that allows light to propagate in only one direction. Optical isolators are typically used to protect light sources from back reflections or signals that can cause instabilities and damage. The operation of optical isolators depends on the Faraday effect, which is used in the main component, the Faraday rotator.

optical isolator

Fiber Optic Sensor: a fiber optic sensor is a sensor that uses optical fiber either as the sensing element (intrinsic sensors), or as a means of relaying signals from a remote sensor to the electronics that process the signals (extrinsic sensors). Fiber optic sensors are immune to electromagnetic interference, and do not conduct electricity so they can be used in places where there is high voltage electricity or flammable material such as jet fuel.

fiber optic sensor

Pump Combiner: a pump combiner is a passive optical component built based on fused biconical taper (FBT) technique. Pump combiners are widely used in fiber laser, fiber amplifier, high power EDFA, biomedical and sensor system etc. Three types of pump combiners are available: Nx1 Multimode Pump Combiner, (N+1)x1 Multimode Pump and Signal Combiner, PM(N+1)x1 PM Pump and Signal Combiner.

pump combiner

Polarization Components: polarization is the state of the e-vector orientation. Polarization components are used to isolate and transmit a single state of polarized light while absorbing, reflecting, and deviating light with the orthogonal state of polarization. Polarization components can be utilized in high power optical amplifiers and optical transmission system, test and measurement.

polarization components

Fiberstore has all of the above passive optical components with high quality and reasonable price. You can select excellent passive optical components or other optical products for your network at www.fs.com.

BiDi Transceiver Overview

For several years ago, when talked about fiber optic transceiver, almost most of people engaged in telecommunication industry would tell that a transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry. Almost all fiber optic transceivers uses two fibers to transmit data between routers and switches. One fiber is devoted to transmitting data to the networking equipment, while the other one is devoted to receiving data from the networking equipment. For recent years, a new kind of fiber optic transceiver has been available — Bi-Directional transceiver (BiDi transceiver).

BiDi Transceiver Basis

BiDi transceiver is a type of fiber optic transceiver which uses WDM (wavelength division multiplexing) bi-directional transmission technology so that it can achieve the transmission of optical channels on a fiber propagating simultaneously in both directions. BiDi transceiver is only with one port which uses an integral bidirectional coupler to transmit and receive signals over a single optical fiber (see the following picture). BiDi transceivers are specifically designed for the high-performance integrated duplex data link over a single optical fiber and used in bi-directional communication applications. The BiDi transceivers interface a network device mother board (for a switch, router or similar device) to a fiber optic or unshielded twisted pair networking cable.

BiDi transceiver

Working Principle of BiDi Transceiver

The difference between BiDi transceivers and the two-fiber optical transceiver mainly lies in that BiDi transceivers are fitted with WDM couplers, also known as diplexers, which help to combine and separate data transmitted over a single fiber based on the wavelengths of the light. So BiDi transceivers are also called WDM transceivers. BiDi transceivers are usually deployed in matched pairs to get the work most efficiently. And the diplexers of BiDi transceivers are tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to.

As can be seen from the following diagram, the paired BiDi transceivers are being used to connect two devices. Device A is used to get upstream data, and Device B is used to get downstream data. Tx means transmit. Rx means receive. The diplexer in one transceiver (Device A) should have a transmitting wavelength of 1310 nm and have a receiving wavelength of 1550 nm. The diplexer in the other transceiver (Device B) should have a transmitting wavelength of 1550 nm and have a receiving wavelength of 1310 nm.

BiDi transceiver

Advantages of BiDi Transceiver

The decisive advantage of using BiDi transceiver is that it helps to reduce the cost of fiber cabling infrastructure. This is caused by reducing the number of fiber path panel ports as well as reducing the amount of tray space dedicated to fiber management. The deployment of BiDi transceiver enables the bandwidth capacity of the optical fiber to be doubled.

FS.COM BiDi Transceiver Solution

FS.COM supplies a series of BiDi transceivers with different types such as BiDi SFP. These BiDi Gigabit SFP transceivers support Fast Ethernet, Gigabit Ethernet, and Fibre Channel, etc. And they can be available for simplex SC or LC connector interface, which is used for data transmitting and receiving. Also, the BiDi SFPs are able to support a wide range of physical media from copper to long-wave single-mode optical fiber with transmission distance up to hundreds of kilometers. The most typical Tx and Rx wavelength combinations are 1310/1490 nm, 1310/1550 nm and 1490/1550 nm. FS.COM has a large selection of BiDi transceivers in stock. Choosing a FS.COM BiDi transceiver can help your fiber optic network to be most economical and efficient.

Related Article: A Brief Introduction of BiDi SFP Transceiver