Basic of Optical Distribution Frame (ODF)

Driven by requirements for high-speed data rate, the deployment of fiber optic has been growing. As the growth of installed fiber optic, the management of optical transmission networks becomes more difficult. Many factors should be considered during fiber optic cabling, like flexibility, future viability, cost of the deployment and management, etc. To handle large amounts of fiber optic with lower cost and higher flexibility, various optical distribution frames (ODF) are being widely used to connector and schedule optical fiber. Choosing right fiber optic distribution frames is the key to successful cable management.

What Is ODF?

An optical distribution frame (ODF) is a frame used to provide cable interconnections between communication facilities, which can integrate fiber splicing, fiber termination, fiber optic adapters & connectors and cable connections together in a single unit. It can also work as a protective device to protect fiber optic connections from damage. The basic functions of ODFs provided by today's vendors are almost the same. However, they come into different shapes and specifications. To choose the right ODF is not an easy thing.

Types of ODF

According to the structure, ODFs can mainly be divided into three types, namely wall mount ODF, floor mount ODF and rack mount ODF.

Wall mount ODF (shown in the following picture) usually uses design like a small box which can be installed on the wall and is suitable for fiber distribution with small counts. Floor mount ODF adopts closed structure. It is usually designed with relatively fixed fiber capacity and nice appearance.

Rack mount ODF (shown in the following picture) is usually modularity in design with firm structure. It can be installed on the rack with more flexibility according to the fiber optic cable counts and specifications. This kind of optical distribution system is more convenient and can provide more possibilities to the future variations. Most of the rack mount ODF is 19'', which ensures that they can be perfectly installed on to the commonly used standard transmission rack.

ODF Selection Guide

The selection of the ODF is not limited to the structure, many factors like applications should be considered. Some of the most important are introduced as following.

Fiber Counts: with the number of fiber connections in places like data center increase, the need for high density ODF become the trend. And it is very common to find ODF with 24 ports, 48 ports or even 144 ports for fiber optic cables in the market now. Meanwhile, many vendors can provide the customized ODFs according to the customers' requirement.

Manageability: High-density is the good but management is not easy. ODF should provide an easy management environment for technicians. The basic requirement is ODF should allow for easy access to the connectors on the front and rear of those ports for insertion and removal. This requires that ODF should reserve enough space. In addition, the color of adapters installed on the ODF should be remain consistent with the color code of fiber optic connectors to avoid wrong connections.

Flexibility: as mentioned rack mount ODF is relatively flexible during applications with the modular design. However, anther aspect which can increase the ODF’s flexibility effectively is the port size for adapters on the ODF. For example, an ODF with ports of duplex LC adapter size can be installed with duplex LC, SC or MRTJ adapters. An ODF with ports of ST adapter size can be installed with both ST adapters and FC adapters.

Protection: optical distribution frames integrate fiber connections in it. The fiber connections like splicing joint, fiber optic connectors are actually really sensitive in the whole transmission network and is directly related to the stability and reliability of the network. Thus, a good ODF should have protection device to prevent fiber optic connections from damages produced by dust or stress.

Conclusion

The ODF is the most popular and comprehensive fiber optic distribution frame which can reduce the cost and increase the reliability and flexibility of fiber optic network during both deployment and maintenance. The high density ODF is the trend in telecommunication industry. Selecting an ODF is important and complex which requires full consideration including applications and management. The factors like structure, fiber counts and protection are just the basic elements. The ODF which can meet the current requirements and the challenge of future growing and easing of expansion without sacrificing cable management or density can only be selected with repeated comparison and full consideration.

Source: http://www.fiber-optic-tutorial.com/basic-of-optical-distribution-frame-odf.html

Fiber Patch Cable Management

Deploying more fiber optic cable is just the first step to meet the high-bandwidth requirements, strong management over the fiber optic cable is a basic requirement for a successful fiber optic network infrastructure. Fiber patch cable might be the weakest link in optical network infrastructures. To deliver and guarantee and optimal network performance, patch cable management is critical. In addition, well management of fiber patch cable can lower operation cost & time and increases the reliability and flexibility of network operation and maintenance. This post will offer the critical elements that should be noted during patch cable management, as well as tips for fiber patch cable management.

Elements That Affects Patch Cable Management

To get a flexible and well organized patch cable management, the factors that affect the performance of the fiber optic patch cable should be introduced first. Here are four key elements that should be considered during patch cable management.

Bend Radius

Unlike copper, fiber optic made of glass is much fragile and need more protection and attention during the operation and management. Thus, the fiber’s bend radius will impact its reliability and performance. If a fiber cable is bent excessively, the optical signal within the cable may refract and escape through the fiber cladding which will cause a loss of signal strength and is known as bend loss. What’s more, bending, especially during the installation and pulling of fiber optic patch cable might also cause micro cracks and damage the fiber permanently. Generally, there are two basic types of bends in fiber, which are microbends and macrobends as shown in the following picture. The macrobends are larger than microbends.

What should be noted is that bend radius might not be seen during the initial installation of fiber patch cable. This is because the number of patch cables routed to the optical distribution ODF is usually small. However, when more patch cords are added on the top of installed patch cables in the future the problems will come across (shown in the following picture). A fiber patch cable that working fine for years might suddenly have an increased level of attenuation, as well as a potentially shorter service life.

Path of Patch Cable

Patch cable path is an aspect closely related to bend radius that can affect the performance and maintenance of the patch cable. The path of the patch cable should be clearly defined and easy to follow. Improper cable routing can cause increased congestion in the termination panel, increasing the possibility of bend radius violations and long-term failure. However, the well managed patch cable path ensures that bend radius requirements are maintained at all points and makes accessing individual patch cable easier, quicker and safer. What should be mentioned is that the well organized fiber patch cords can help to decrease operating costs and the time required to turn-up or restore service.

Accessibility of Patch Cable

The third aspect is accessibility of the installed patch cable. If the installed patch cable is easy to be accessed, the maintenance and operation would be quick without inducing a macrobend on an adjacent fiber, and it can also offer proper bend radius protection. Accessibility is critical during network reconfiguration operations and directly impacts operation costs and network reliability.

Physical Protection

Patch cables routed between pieces of equipment can largely affect network reliability. Without proper protection, they would be easy to be damaged by technicians and equipment accidentally. Thus, physical protection of the installed patch cords is very important.

Tips for Fiber Patch Cable Management

According to the mentioned aspects that can affect the performance and maintenance of the fiber optic patch cable, here offers several tips that can help to increase the performance of patch cords, as well as the reliability and flexibility of patch cable management.

Tip 1: Pay attention to the bend radius of the patch cable. Generally, for 1.6mm and 3.0mm cords the minimum un-loaded bend radius is 3.5 cm, and the minimum bend radius of MPO patch cable is ten times the cord diameter.

Tip 2: Never pull or stress the patch cords (shown in the following figure). During the patching process, excessive force can stress fiber patch cables and connectors attached to them, thus reducing their performance. There might be something wrong if you need to use force in pulling a cord.

Tip 3: Routing cords through cable pathways. If the existing cord is the right length, it may be possible to re-use it. If this is the case, remove the cord completely and re-run it in through the cable pathways. This is the only sure way to ensure there are no tangles, kinks or strains in the cord. For efficient routing, find the best path between the ports to be connected. Avoid routing cords through troughs and guides that are already congested.

Tip 4: Bundling and tying cords gives the panel a neat appearance but tight bundling increases the risk of pinching (shown in the following figure). Do not tighten cable ties beyond the point where individual cords can rotate freely.

Tip 5: Labeling is necessary. Labeling is the most important part of a System Administrator’s responsibilities. At any administration point in a cabling infrastructure, including patching panels, accurate labels are essential. These will identify pair modularity and tell technicians where the other end of the cable is terminated.

Tip 6: Inspect fiber cords for physical damage including stress marks from sharp bends on the sheath, or damage to connectors as shown in the following figure.

Conclusion

A strong and successful patch cable management which can increase the reliability and flexibility and decrease the cost of network operation and maintenance should provide bend radius protection, reasonable patch cable path, easy accessibility of patch cable and physical protection. When the four mentioned aspects are satisfied, there is already half the success to strong patch cable management.

Source: http://www.fiber-optic-tutorial.com/fiber-patch-cable-management.html

Causes of Mechanical Splice Termination Failures

FTTH (fiber to the home) has become increasingly popular in optical communication industry. Fiber optic termination, as one of the topics which have never been out of fashion in this field, has naturally become a focus of FTTH network deployment, especially the indoor termination. In FTTH network, mechanical splice connectors are usually used in FTTH indoor termination with the advantages of flexibility, fast-installation and cost-effective. Currently manufactures can provide various types of mechanical splice connectors of high quality which have low insertion loss and high performance. However, no matter how excellent the mechanical splicing technology is, there are still fiber optic termination failures and bad fiber optic termination due to improper operation. To avoid it, this post is to offer the causes of mechanical splice termination failures.

The Basic of Mechanical splicing

Before finding the cause of mechanical splice failure, the basic of mechanical splicing should be introduced. To finish a mechanical splice, the buffer coatings of fiber optic should be removed mechanically with sharp blades or calibrated stripping tools. In any type of mechanical stripping, the key is to avoid nicking the fiber. Then the fibers will be cleaved. Two fiber ends are then held closely in retaining and aligning a mechanical splice connector with some index matching gel between them. The gel are used to form a continuous optical path between fibers and reduce reflecting losses.

Causes of Mechanical Splice Termination Failures

Mechanical splice connector is sensitive to many factors. There are also a large number of factors to cause failures. However, most of the factors are located at the end face of fiber optic. The following is to describe them in details.

Contamination

When facing mechanical splice failures, there would be no argument that contamination is the first thing to think about. There are many ways that contamination can be carried into the fiber termination splices. Generally, there are the following possible causes of splice contamination:

• Using a dirty cleave tool: as the fiber should be cleave before inserted in the connector, a fiber optic cleaves would be used. If a dirty cleave is used, the contamination would be attached on the end face of the fiber optic and be embedded in the connector. Thus, do remember to clean the surfaces thoroughly with alcohol wipes;
• Wiping the fiber after cleaving;
• Setting the connector or fiber down on a dusty surface;
• Heavy airborne dust environment;
• Glass fragments from insertion broken fibers, or applying excessive force;
• Polluted index matching gel.

Please note that once the contamination is carried inside the mechanical splice connector, especially with the index matching gel, there would be little possibility to clean them out, which means the connector may be scrapped.

Glass Fragmentation

Improper operation like overexertion when inserting the fiber optic into the mechanical splice connector might break the fiber optic and produce glass fragmentation which will cause air gap and optical failure. Or if a broken fiber if inserted, there will also be optical failure. If the glass fragments are embedded in the connector, they cannot be cleaned out and the connector would be scrapped. Thus, be gentle and carefully when splicing the fiber ends.

Bad Cleave

Cleaving the fiber optic is an important step during fiber optic mechanical splicing. The quality of the cleave can decide the quality of the optical splice transmission to some degree. It is not easy to inspect the cleave quality in the field. There are several possibilities there might cause the bad cleaves:

• Dull or chipped cleave tool blade
• The bent tongue on the cleave tool concentrated too much bend stress on the fiber
• Bending the fiber too much or too tight of a radius
• Applying no tension or insufficient tension to the fiber while cleaving.

Excessive Fiber Gap

Fiber gap is another factor that might cause the fiber optic termination failure. The fiber optic transmission is very sensitive to the gap between two fiber ends in the mechanical splice connector. Improper operations that might cause the excessive fiber gap are listed as following:

• Cleaving the fiber without enough lengths;
• The fiber is not fully inserted, or pulled back during termination;
• The fiber was not held steady during termination and was pushed back into the fan-out tubing when terminating outdoor cable.

These faults can be corrected one time.

Excessive Cleave Angle

During fiber cleaving, cleave angle can be produced easily and is difficult to be inspected in field. These angles are typically ranging from 1 to 3 degree. Even with precision tool, there might still be cleave angle ranging from 0.5 to 1 degree. The angle is generally produced by bent tongue, fiber bending or insufficient fiber tension.

However the cleave angles can be corrected by fine tuning with a VFL (visual fault locator). Rotating the fiber while using a VFL and terminate the connector at the position (as shown in the following picture).

Conclusion

Fiber optic mechanical splicing gives quick and high quality result at a low price for fiber optic termination. Choosing the right fiber optic mechanical splice connector and fiber optic cleaver of high quality is not enough. Acknowledge the possible causes to fiber optic termination failures and use the right tools with skills can reduce the risk of termination failure effectively.

Source: http://www.fiber-optic-tutorial.com/causes-of-mechanical-splice-termination-failures.html

Understand Polarity in MPO System

MPO/MTP technology, which is of high density, flexibility and reliability with scalable, upgradeable properties, is one of the contributors that lead the migration to 40/100GbE. However, the network designers face another challenge which is how to assure the proper polarity of these array connections using multi-fiber MPO/MTP components from end-to-end. Maintain the correct polarity across a fiber network ensures that a transmit signal from any type of active equipment will be directed to receive port of a second piece of active equipment – and vice versa. To ensure the MPO/MTP systems work with correct polarity, the TIA 568 standard provided three methods, which will be introduced in this article.

MPO Connector

To understand the polarity in 40/100 GbE Transmission, the key of MPO technology—MPO connector should be first introduced. MPO connector usually has 12 fibers. 24 fibers, 36 fibers and 72 fibers are also available. Each MTP connector has a key on one of the flat side added by the body. When the key sits on the bottom, this is called key down. When the key sits on top, this is referred to as the key up position. In this orientation, each of the fiber holes in the connector is numbered in sequence from left to right and is referred as fiber position, or P1, P2, etc. A white dot is additionally marked on one side of the connector to denote where the position 1 is. (shown in the following picture) The orientation of this key also determines the MPO cable's polarity.

Three Cables for Three Polarization Methods

The three methods for proper polarity defined by TIA 568 standard are named as Method A, Method B and Method C. To match these standards, three type of MPO truck cables with different structures named Type A, Type B and Type C are being used for the three different connectivity methods respectively. In this part, the three different cables will be introduced firstly and then the three connectivity methods.

MPO Trunk Cable Type A: Type A cable also known as straight cable, is a straight through cable with a key up MPO connector on one end and a key down MPO connector on the opposite end. This makes the fibers at each end of the cable have the same fiber position. For example, the fiber located at position 1 (P1) of the connector on one side will arrive at P1 at the other connector. The fiber sequence of a 12 fiber MPO Type A cable is showed as the following:

MPO Trunk Cable Type B: Type B cable (reversed cable) uses key up connector on both ends of the cable. This type of array mating results in an inversion, which means the fiber positions are reversed at each end. The fiber at P1 at one end is mated with fiber at P12 at the opposing end. The following picture shows the fiber sequences of a 12 fiber Type B cable.

MPO Trunk Cable Type C: Type C cable (pairs flipped cable) looks like Type A cable with one key up connector and one key down connector on each side. However, in Type C each adjacent pair of fibers at one end are flipped at the other end. For example, the fiber at position 1 on one end is shifted to position 2 at the other end of the cable. The fiber at position 2 at one end is shifted to position 1 at the opposite end etc. The fiber sequence of Type C cable is demonstrated in the following picture.

Three Connectivity Methods

Different polarity methods use different types of MTP trunk cables. However, all the methods should use duplex patch cable to achieve the fiber circuit. The TIA standard also defines two types of duplex fiber patch cables terminated with LC or SC connectors to complete an end-to-end fiber duplex connection: A-to-A type patch cable—a cross version and A-to-B type patch cable—a straight-through version.

The following part illustrates how the components in MPO system are used together to maintain the proper polarization connectivity, which are defined by TIA standards.

Method A: the connectivity Method A is shown in the following picture. A type-A trunk cable connects a MPO module on each side of the link. In Method A, two types of patch cords are used to correct the polarity. The patch cable on the left is standard duplex A-to-B type, while on the right a duplex A-to-A type patch cable is employed.

Method B: in Connectivity Method B, a Type B truck cable is used to connect the two modules on each side of the link. As mentioned, the fiber positions of Type B cable are reversed at each end. Therefore standard A-to-B type duplex patch cables are used on both sided.

Method C: the pair-reversed trunk cable is used in Method C connectivity to connect the MPO modules one each side of the link. Patch cords at both ends are the standard duplex A-to-B type.

Conclusion

Network designer using MPO/MTP components to satisfy the increasing requirement for higher transmission speed, during which one of the big problems—polarity, can be solved by selecting the right types of MPO cables, MPO connectors, MPO cassette and patch cables. The three different polarization methods can be applied according to the satisfy requirements in different situations. For more information about polarity in MPO systems and 40/100GbE transmission polarity solutions, please visit Fiberstore tutorial at "Polarity and MPO Technology in 40/100GbE Transmission".

Source: http://www.fiber-optic-tutorial.com/understanding-polarity-in-mpo-system.html

Upgrade to High Data Rate Transmission With Parallel Optics

Parallel optics represent a type of optical communication technology as well as the devices on either end of the link that transmit and receive information which are also known as parallel optical transceivers. Compared with traditional optical communication, parallel optical communication employs a different cabling structure for signal transmitting aiming at high-data transmission for short reach multimode fibers that are less than 300 meters. Traditional fiber optic transceivers cannot satisfy the increasing demand for high speed transmission, like 40GbE, while parallel optics technology can be a cost effective solution for 40/100GbE transmission.

Comparison between parallel optics technology and the traditional serial optical communication would better explain what parallel optics is and the reason why it is a cost effective solution to high data rate transmission. The following of this article will offer the comparison between the two optical communication technology from two aspects: connectivity method and key components.

Connectivity Method

Literally, parallel optics and serial optics transmit signals in different ways. In traditional serial optical communication, on each end of the link, there are one transmitter and one receiver. For example, the transmitter on End A communicates to the receiver on End B, sending a single stream of data over a single optical fiber. And a separate fiber is connected between the transmitter on End B and the receiver on End A. In this way, a duplex channel is achieved by two fibers.

While in parallel optical communication, duplex transmission is achieved in a different way. A signal is transmitted and received through multiple paths, thus, the parallel optical communication can support higher data rate than the traditional optical communication. This is because, the devices for parallel optic communication on either end of the link contain multiple transmitters and receivers. For instance, in 2010 IEEE 802.3ba approved the 40GBASE-SR4 physical-medium-dependent multimode parallel optical solution, which uses eight fibers to transmit four duplex channels each at 10 Gigabit Ethernet. In this case, four 10Gbps transmitters on End A communicate with four 10Gbps receivers on End B, spreading a single stream of data over four optical fibers at a total data rate of 40Gbps.

Key Components

The parallel optical communication transmitting signals over multiple fibers, which has great advantages over traditional serial optical communication. It also means that it requires different components to support its high data rate transmission.

Connector: As previously mentioned, duplex transmission in serial optical communication uses 2-fiber duplex connectors, like duplex LC connectors to link the optics with other devices, while in parallel optical communication, multi-fibers are used to reach a higher data rate. Thus, multi-fiber connectors, like 12-fiber MPO connectors are used to connect with other devices. MPO connector is one key technology support parallel optical communication. This connectivity method is showed in the following picture?(Tx stands for transmit; Rx stands for receive).

Optical transceiver light source: Another complementary technology for parallel transmission is the light source of parallel optics—VCSELs (Vertical Cavity Surface Emission Lasers). Comparing with the edge-emitting semiconductor lasers in the traditional optics, VCSELs have better formed optical output which enables them to couple that energy into optical fibers more efficiently. In addition, VCSELs emit from the top surface, they may be tested while they are part of a large production batch (wafer), before they are cut into individual devices, which dramatically lowers the cost of the lasers. The following chart is about the comparison between VCSELs and edge-emitting semiconductor lasers. Cheaper to manufacture, easier to test, less electrical current required, supporting higher data rate, parallel optics using VCSELs could be a better choice to reach 40/100GbE transmission compared with traditional serial optics.

VCSEL vs Edge-Emitting Laser

Feature	VCSEL	Edge-Emitting Laser
Power consumption	2-3 mW	20 mW
Beam quality/ease of coupling	Better, round low divergence	Fine, asymmetric
Speed	10 Gbps	1 Gbps
Temperature stability	0.06 nm/oC	0.25 nm/oC
Specral width	1 nm	1-2 nm
Speckle	Low in an array	High

 

Parallel Optics for 40/100GbE Transmission

IEEE has already included physical layer specifications and management parameters for 40Gbps and 100Gbps operation over fiber optic cable. Two popular parallel optics solutions for 40Gbps and 100Gbps over multimode fibers are introduced here. For 40G, 40GBASE-SR4 transceiver is usually used, which requires a minimum of eight OM3/OM4 fibers for a transmit and receive link (4 fibers for Tx and 4 fibers for Rx). 100GBASE-SR10 transceiver is for 100Gbps transmission, which requires a minimum of 20 OM3/OM4 fibers for a Tx/Rx link, 10 fibers are used for Tx and the other 10 are for Rx.

Conclusion

The capabilities and uses of parallel optics and MPO technology continue to evolve and take shape as higher-speed fiber optic transmission, including 40/100GbE. It is uncertain that parallel optical communication would be the trend in the future. However, many cabling and network experts have pointed out that parallel optical communication supported with MPO technology is currently a way to equip an environment well prepared for the 40/100GbE transmission.

Source: http://www.fiber-optic-tutorial.com/upgrade-to-high-data-rate-transmission-with-parallel-optics.html

Migrating to 40/100G With OM3/OM4 Fiber

To meet the continuously increased requirements, data center 40/100G migration is underway. The infrastructure of data centers for the 40G/100G should meet the requirements like high speed, reliability, manageability and flexibility. To meet these requirements, product solutions and the infrastructure topology including cabling must be considered in unison. Cable deployment in the data center plays an important part. The cable used in data center must be selected to provide support for data rate applications not only of today but also the future. Today, two types of multimode fiber—OM3 and OM4 fibers (usually with aqua color)—have gradually become the media choice of data center during 40/100G migration. This article illustrates OM3/OM4 multimode fibers in 40/100G migration in details.

Data Center and Multimode Fibers

Multimode fiber is being widely used in data centers. You might ask why not single-mode fiber? The answer is cost. As is known to all, the price of single-mode fiber is generally more expensive than multimode fiber. In addition multimode fibers provide a significant value proposition when compared to single-mode fiber, as multimode fiber utilizes low cost 850 nm transceivers for serial and parallel transmission. If you had all money you wanted and you’d just run single-mode fiber which has all the bandwidth you need, then you can go plenty of distance. However, this perfect situation would cost a lot of money. Thus, most data center would choose multimode fiber. OM1, OM2, OM3 and OM4 are the most popular multimode fiber. But OM3 and OM4 are gradually taking place of OM1 and OM2 in data centers.

OM stands for optical multimode. OM3 and OM4 are both laser-optimized multimode fibers with 50/125 core, which are designed for use with 850nm VCSELS (vertical-cavity surface-emitting laser) and are developed to accommodate faster networks such as 10, 40 and 100 Gbps. Compared with OM1 (62.5/125 core) and OM2 (50/125 core), OM3 and OM4 can transport data at higher rate and longer distance. The following statistics (850 nm Ethernet Distance) shows the main differences between these four types multimode fibers, which can explain why OM3 and OM4 is more popular in data center now in some extent.

850 nm Ethernet Distance

Fiber 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

 

Why Use OM3 and OM4 in 40/100G Migration

The Institute of Electrical and Electronics Engineers (IEEE) 802.3ba 40/100G Ethernet Standard was ratified in June 2010. The standard provides specific guidance for 40/100G transmission with multimode and single-mode fibers. OM3 and OM4 are the only multimode fibers included in the standard. The reason why OM3 and OM4 are applied in 40/100G migration is that they can meet the requirements for the migration cabling performance.

Bandwidth, total connector insertion loss and transmission distance are two three main factors should be considered when evaluation the performance needed for cabling infrastructure to meet the requirements for 40/100G. These factors can impact the cabling infrastructure’s ability to meet the standard’s distance of at least 100 meters over OM3 fiber and 150 meters over OM4 fiber. The following explains why OM3/OM4 are the chosen ones for 40/100G migration.

Get Higher Bandwidth With OM3/OM4

Bandwidth is the first reason why OM3 and OM4 are used for 40/100G migration. OM3 and OM4 are optimized for 850nm transmission and have a minimum 2000 MHz?km and 4700 MHz?km effective modal bandwidth (EMB). Comparing the OM1 and OM2 with a maximum 500 MHz?km, advantages of OM3 and OM4 are obvious. With a connectivity solution using OM3 and OM4 fibers that have been measured using the minimum Effective Modal Bandwidth calculate technique, the optical infrastructure deployed in the data center will meet the performance criteria set forth by IEEE for bandwidth.

Get Longer Transmission Distance With OM3/OM4

The transmission distance of fiber optic cables will influence the data center cabling. The manageability and flexibility will be increased with fiber optic cables with longer transmission distance. OM3 fiber and OM4 fiber can support longer transmission distance compare with other traditional multimode fibers. Generally OM3 fibers can run 40/100 Gigabit at 100 meters and OM4 fibers can run 40/100 Gigabit at 150 meters. This high data rate and longer distance cannot be achieved by other traditional multimode fiber like OM1 and OM2. Employing OM3 fiber and OM4 in 40/100G migration is required.

Get Lower Insertion Loss With OM3/OM4

Insertion loss has always been an import factor that technically should consider during the data center cabling. This is because the total connector loss within a system channel impacts the ability to operate over the maximum supportable distance for a given data rate. As total connector loss increased, the supportable distance at that data rate decreases. According to the 40/100G standard, OM3 fiber is specified to a 100m distance with a maximum channel loss of 1.9dB, which includes a 1.5dB total connector loss budget. And OM4 fiber is specified to a 150m distance with a maximum channel loss of 1.5 dB, including a total connector loss budget of 1.0 dB. With low-loss OM3 and OM4 fiber, maximum flexibility can be achieved with the ability to introduce multiple connector mating into the connectivity link and longer supportable transmission distance can be reached.

OM3 or OM4?

Choosing OM3/OM4 is a wise and required choice for data center 40/100G migration. However, OM3 and OM4, which is better? Numerous factors can affect the choice. However, the applications and the total costs are always the main factors to consider to figure out whether OM3 or OM4 is needed.

First, the connectors and the termination of the connectors for OM3 and OM4 fibers are the same. OM3 is fully compatible with OM4. The difference is just in the construction of fiber cable, which makes OM4 cable has better attenuation and can operate higher bandwidth at a longer distance than OM3. Thus, the cost for OM4 fiber is higher than OM3. As 90 percent of all data centers have their runs under 100 meters, choosing OM3 comes down to a costing issue. However, looking in the future, as the demand increases, the cost will come down. Thus, OM4 might be the most viable product at some point soon.

No matter choosing OM3 or OM4, the migration is underway. With good performance like high data rate, long transmission distance and lower inserting loss, OM3/OM4 fiber is a must in data center migration to 40/100G.

Source: http://www.fiber-optic-tutorial.com/migrating-to-40100g-with-om3om4-fiber.html

G.fast Offers Fiber Speed Ethernet Over Copper

The demand for higher data rates is continuously increasing driven by the applications like Cloud Computing, Big Data and Internet of Things. Meanwhile, the strong market competition makes the network operators to improve the network architecture and deliver high speed services. Pure fiber network should be the best solution. There is no wonder that the fiber network is the trend of the future and it is gradually extended closer to users during the transition from copper-based access networks to pure fiber networks. However, it is not favorable to connect the fiber directly to the customer premises and the cost is high in some cases, like old buildings. To find the fast and cost-effective way to deliver Gigabit speed Ethernet, copper access technology is being applied in some cases. This technology is known as G.fast.

G.fast and FTTdp

G.fast, based on the latest VDSL technology including cross talk cancellation and re-transmission, is designed for use in a 'last-mile' of less than 250 meters. Combining the advantages of fiber optic access technology and copper access technology, G.fast can deliver data at fiber speed to the customers using telephone copper wires.

The problem with G.Fast is that its ultra-fast speeds only work over very short distances. To shorten the copper distance, FTTdp is usually applied with G.fast. "dp" here stands for "distribution point". This solution brings the fiber optic cable out of street cabinets and moves it closer to home via the distribution point. The following network diagram shows the difference of FTTH and FTTdp using G.fast. The blue lines represent fiber optic cable, the red ones represent copper wire.

G.fast Shifts the Limits of Copper

It seems that there is no need for copper access in building a FTTx connection. But in practice, connecting the fiber directly to the customer premises causes some disadvantages which can be solved by G.fast.

There might be many difficulties when deploying fibers to the user homes, especially some existing buildings. Sometime it is even not possible to deploy fibers to the user homes. In addition, most in-house telephone installations still rely on copper cables for most existing and newly constructed buildings because fibers are expensive and difficult to handle. There is no need to deploy fiber optic cable in building and home when delivering Gigabit Ethernet with G.fast.

The fiber optic based customers premises equipment (CPE) are usually installed by technician. Compared with fiber optic connections, copper-based CPE installation is simple. Just connecting the CPE to the telephone plug with the delivered cable would finish the installation, which can be installed by customer. Thus, G.fast can save the cost for new users and makes the home installation much easier.

Optical fibers can be broken or have transmission loses when wrapped around curves and optical fibers require more protection around the cable compared to copper. What’s more, the fault location from the CPE is not easy. It would cost more to maintain the fiber connections compared with copper connections achieved by G.fast.

G.fast Paves the Way to FTTH

At first glance, G.fast is limiting the transmission from copper to fiber. Actually, G.fast accelerates the deployment of fiber optic networks. It cost a lot of time and money to process the paperwork and get permission of the subscriber before deploying the fiber optic cable. The processing is complicated. Hardware foundation is the main advantages of G.fast which eliminates the need to rewire the whole building and still allows a noteworthy uplift in access speeds. Copper is everywhere in telecommunication network. The hybrid copper/fiber approach—G.fast making full use of the telephone wires in the buildings actually makes the customers closer to optical fibers in time save and cost save manners. In this way, the transmission from copper to fiber is actually being promoted by G.fast.

Weighing time, broadband speed and cost, operators figure out that applying G.fast in FTTH is an economical and time-saving way to bring Gigabit speed Ethernet to the users. To capture market share of broadband service, some network operators are considering to use G.fast. Alcatel-Lucent and communications services company BT have already started a consumer trial of G.fast technology in Gosforth (situated in North-Eastern England), for offering ultra-broadband access to consumers.

Source: http://www.fiber-optic-tutorial.com/g-fast-offers-fiber-speed-ethernet-over-copper.html

Do You Know Digital Diagnostic Monitoring?

Cisco announced the end of sale of its SFP transceiver Cisco GLC-SX-MM transceiver and published a replacement—Cisco GLC-SX-MMD transceiver in 2012. The module numbers of the two transceiver only differ in one letter "D". This "D" mainly represents a function of Cisco GLC-SX-MMD transceiver and is inherited by most of optical transceivers offered today. It is the main reason why Cisco GLC-SX-MMD transceiver can replace its predecessor. What is this "D"? Why the GLC-SX-MMD can replace GLC-SX-MM? This article is to offer the answers to these questions.

What Is Digital Diagnostic Monitoring (DDM)?

"D" in GLC-SX-MMD represents the DDM function which is short for digital diagnostic monitoring according to the industry standard MSA (Multi-Source Agreement) SFF-8472 and is also known as DOM (Digital Optical Monitoring). When buy fiber optic transceiver today, you will have the option with or without DDM/DOM. And most of the modern transceivers are with the DDM function. This technology allows the user to monitor real-time parameters of the fiber optic transceivers, like optical input/output power, temperature, laser bias current, and transceiver supply voltage, etc.

What Can Digital Diagnostic Monitoring Do?

Literally, DDM function can provide component monitoring on transceiver applications in details. However, DDM’s application is not limited to this. The SFF-8472 added DDM interface and outlined that DDM interface is an extension of the serial ID interface defined in GBIC specification, as well as the SFP MSA. DDM interface includes a system of alarm and warning flags which alert the host system when particular operating parameters are outside of a factory set normal operating. Thus, DDM interface can also enable the end user with the capabilities of fault isolation and failure prediction. This part is to illustrate what can be done with DDM.

Component Monitoring: The DDM enables the end user to monitor key parameters in the performance of the fiber optic transceiver including the following:

• Transceiver temperature
• Transceiver supply voltage
• Laser bias current
• Transmit average optical power
• Received optical modulation amplitude (OMA) or Average Optical Power

The real-time diagnostic parameters can be monitored to alert the system when the transceiver’s specified operating limits are exceeded and compliance cannot be ensured.The following picture shows the eye diagram illustrating optical figures of merit.

Fault isolation: The DDM function can be used to isolate the particular location of fault in fiber optic network system. Combining the DDM interface status flags, transceiver hard pins and diagnostic parametric monitor data, the specific location and cause of a link failure can be pinpointed.

Failure prediction: The DDM can also be used to help in failure prediction on fiber optic links, which is based on the transceiver parametric performance. Although, this application is not yet fully mature, but there is still room for improvement. There are two basic types of failure conditions that can be seen on fiber optic transceivers:

• Device faults—A device non-operation or malfunction. Typically applied more to transmitter performance, due to nature of semiconductor lasers.
• High error rate conditions—Operating conditions are such that transceiver is operating at its signal-to-noise limit. Applies more to fiber optic receiver performance.

Providing parameter monitoring, fault isolation, and failure prediction, fiber optic transceivers with DDM help to ensure that the business can be proactive in preventative maintenance of the network and ensure business continuity. And it would easy to explain why modern transceivers are with DDM and why GLC-SX-MMD can replace GLC-SX-MM. It is irresistible development trend of industry and technology.

What should be mentioned is that although optical transceivers with DDM are much popular than those without DDM, some user still use the older optical transceivers in consideration of the upgrading costs. To satisfy the customers’ needs, optical transceivers with DDM and without DDM are provided by the vendors like Fiberstore.

Source: http://www.fiber-optic-tutorial.com/do-you-know-digital-diagnostic-monitoring.html

Guide to Fiber Optic Attenuator

Many components are used to enlarge the signals in today's fiber optic transmission system, like EDFA (Erbium-Doped Fiber Amplifier). However, in some cases, the power level of an optical signal should be reduced. For example, in DWDM (dense wavelength division multiplexing) systems, multiple wavelength channels arriving at a node may pass though different paths and experience different losses, their powers need to be equalized before entering the optical amplifier to get flat gain since the gain of each channel depends on the power levels of the other channels. In this case, a point reduction in optical signal strength may be required. And a component is usually used which is known as fiber optic attenuator. This article is to give a basic introduction of fiber optic attenuator in details.

Introduction

A fiber optic attenuator, also known as an optical attenuator, is a passive component that is used to reduce the power level of an optical signal by a predetermined factor in fiber optic transmission system. The intensity of the signal is described in decibels (dB) over a specific distance the signal travels. Fiber optic attenuators are generally used in single-mode long-haul application.

Working Principles of Fiber Optic Attenuators

As technologies advanced, many principles are used in the operation of fiber optic attenuator to accomplish the desired power reduction. Several operation principles of fiber optic attenuators are being introduced here.

Gap-loss Principle: in attenuator using gap-loss principle, the reduction of the optical power level is accomplished by two fibers that are separated by air to yield the correct loss. The optical signal is attenuated when it passes a longitudinal gap between two optical fibers. This kind of attenuator is also called air gap attenuators which are susceptible to dust contamination and can be sensitive to moisture and temperature variations. In addition, this attenuator is very sensitive to modal distribution ahead of transmitter. Thus, it is recommended to be used very close to the optical transmitter. The farther the air gap attenuator is placed away from the transmitter, the less effective the attenuator is, and the desired loss will not be obtained. To attenuate a signal far down the fiber path, and optical attenuator using absorptive or reflective techniques should be used. Gap-loss principle is showed as following picture.

Absorptive Principle: as the fiber optic has the imperfection to absorb optical energy and convert it to heat. This absorptive principle is used in the design of fiber optic attenuator, using the material in optical path to absorb optical energy. This principle is very simple, however, it can be an effective way to reduce the optical signal power. The following picture shows the absorptive principle.

Reflective Principle: another imperfection of fiber optic is also being used to reduce the signal power, which is reflection. The major power loss in optical fiber is caused by the reflection or scattering. The scattered light causes interference in the fiber, thereby reducing the signal power. Using reflective principle (shown in the picture below), fiber optic attenuator could be manufactured to reflect a known quantity of the signal, thus allowing only the desired portion of the signal to be propagated.

Various principles are being applied to reduce the power single. Also various types of attenuators are being manufactured to meet different applications. The following part is about the main types of the fiber optic attenuators.

Types of Fiber Optic Attenuators

Fixed and variable attenuators are the main types that are being provided in today’s market. Their characteristics are being introduced.

Fixed Attenuator, as the name implies, has a fixed attenuation level. Fixed attenuator can theoretically be designed to provide any amount of attenuation that is desired and be set to deliver a precise power output. Fixed attenuators are typically used for single-mode applications. They mate to regular connectors of the identical type for example FC, ST, SC and LC.

Variable attenuators allow a range of adjustability, delivering a precise power output at multiple decibel loss levels. Variable attenuators can be divided into two types. One is stepwise variable attenuator which can change the attenuation of the single in known steps such as 0.1dB, 0.5dB, or 1 dB. The other one is continuously variable attenuator. This kind of fiber optic attenuator produces precise level of attenuation, with flexible adjustments. It allows the operators to adjust the attenuator to accommodate the changes required quickly and precisely without any interruption to the circuit. They are also available with various fiber optic connectors.

Fiber optic attenuator, an important device to control the power level of optical signal precisely, are being designed to different operation principles and types. Getting the basic knowledge about its working principle and types could help to select the fiber optic attenuator to the required applications.

This article is originally published in http://www.fiber-optic-tutorial.com/guide-to-fiber-optic-attenuator.html

Visual Fault Locator Overview

Whether install new fiber links or troubleshooting an existing network, the faster you can locate a problem, the faster you can fix it. To locate the faults in fiber optic cables in a short time, various fiber optic testers are being invited to locate the faults of the fiber optic cable, like OTDR (optical time-domain reflectometer). However, OTDR has dead zone during the testing. Another simple and useful tester which can work in an OTDR dead zone is usually being used to work as an accessory of OTDR. It is known as VFL (visual fault locator) which can also work alone to locate the faults in fiber optic cable in a time saving manner in some situations.

Visual fault locator is now one of the most commonly used fiber optic testing devices to trace optical fibers, check fiber continuity and find faults such as breaks, bad splices and tight, sharp bends in fiber optic cable. The most popular visual fault locators are pen shape VFL and hand-held VFL, which are showed in the following picture respectively.

How VFL Works
The light used for transmit signals over fiber optic is usually at 1300 to 1650nm wavelength which is invisible to naked eyes. Unlike OTDR which measures the time of the incidence and the amplitude of the reflected pulses sent to the fiber optic cable to locate the faults, VFL uses powerful visible light at the 360 to 670nm wavelength injecting to a fiber to visually and directly locate the faults in fiber optic cable. The visible light travels along the core until it reaches a fault, where it leaks out. Light leaking through the fault can be seen through plastic coating and jackets under suitable illumination. This is how VFL locates the faults in fiber optic cable.

Visual fault locators radiate in continuous wave (CW) or pulse modes. The glint of the light source in VFL is usually at 1 or 2 Hz, kHz range is also being provided in today’s market. The output power is generally at 1 mW or less. The working distance of a VFL is usually in the range of 2 to 5 km.

How to Use VFL
VFL is very easy to use. The steps to use a VFL are provided as following:

Step One: remove the plastic connector covers from both ends of the test fiber cable.
Step Two: connect the fiber optic visual fault locator one end of the fiber. Press the tester button and observe that light emanates from the other end of the fiber. This gives a simple indication of the continuity of the fiber link.
Step Three: repeat with several other fibers. Check for light that can be seen leaking from a faulty splice. This may illustrate an easy way of carrying out visual fault finding on bad splices or joints.
Step Four: disconnect all equipment, put the plastic covers back on the connector ends and return everything to the state it was in before you started the practical so that the next group can carry out the practical in full.

Notes during the using of a VFL:

1.Never look directly into the VFL’s output.
2.Cover the VFL’s output with the dust cap when the VFL is not in use.
3.Not recommended for use on dark colored or armored cables.

Using simple but useful technical principle, visual fault locator individually can provide an economic and time saving solution to locator faults in fiber optic cables in some cases. While working as an accessory of OTDR, VFL, together with OTDR, can provide the fiber technician the best solution to locate fiber faults.

This article is originally published in: http://www.fiber-optic-tutorial.com/visual-fault-locator-overview.html

MPO/MTP Connector – Multi-fiber Connector for High Port Density

In today's transmission networks, small and multi-fiber connectors are replacing larger, older styles connectors for space saving. For example, the SC connector is gradually being replaced by its small version LC connector which allows more fiber ports per unit of rack space. To save space, multi-fiber connector is also a good solution, like MTP/MPO connectors. MTP/MPO connector allows more fiber ports per unit of rack space and also satisfies parallel optical interconnections' needs for multi-fiber connection. This article is to introduce MPO/MTP connectors in details.

MPO Connector & MTP Connector

MPO is short for the industry acronym—"multi-fiber push on". The MPO connector is a multi-fiber connector which is most commonly defined by two documents: IEC-61754-7 (the commonly sited standard for MPO connectors internationally) and EIA/TIA-604-5 (also known as FOCIS 5, is the most common standard sited for in the US). MPO connectors are based on MT ferrule which can provide quick and reliable high performance interconnections up to 4, 12, 24 or more and are usually used with ribbon fiber cables. The following picture shows diagram of MPO connectors, 12-fold (left) and 24-fold (right). The fibers for sending and receiving are colorcoded, red and green, respectively.

MTP stands for "Multifiber Termination Push-on" connector and it is designed by USConec and built around the MT ferrule. MTP connector is a high performance MPO connector designated for better mechanical and optical performance and is in complete compliance with all MPO connector standards. Some main improvements of MTP connector are as following:

• The MTP connector housing is removable;
• The MTP connector offers ferrule float to improve mechanical performance;
• The MTP connector uses tightly held tolerance stainless steel guide pin tips with an elliptical shape;
• The MTP connector has a metal pin clamp with features for centering the push spring;
• The MTP connector spring design maximizes ribbon clearance for twelve fiber and multifiber ribbon applications to prevent fiber damage;
• The MTP connector is offered with four standard variations of strain relief boots to meet a wide array of applications.

Application of MPO/MTP Connector

As mentioned, MPO/MPT connectors are compatible ribbon fiber connectors. MPO/MTP connectors cannot be field terminated, thus MTP/MPO connector is usually assembled with fiber optic cable. MTP/MPO fiber optic cable is one of the most popular MTP/MPO fiber optic cable assemblies, which are now being widely used in data center to provide quick and reliable operation during signal transmission. MPO/MTP connectors can be found in the following ap=-[poikjhnb lications:

• Gigabit Ethernet
• CATV and Multimedia
• Active Device Interface
• Premise installations
• Optical Switch interframe connections
• Interconnection for O/E modules
• Telecommunication Networks
• Industrial & Medical, etc.

MPO/MTP Connector Selection Guide

The structure of MPO/MTP connector is a little complicated. The picture above shows the components of a MPO connector. With the drive of market requests. Various types of MPO/MTP connectors are being provided. Some basic aspects should be considered during the selection of a MPO/MTP connector are as following.

First is pin option. MPO/MTP connectors have male and female design. (as showed in the picture on the left) Male connectors have two guide pins and female connectors do not. Alignment between mating ferrules of MPO/MTP connectors is accomplished using two precision guide pins that are pre-installed into the designated male connector. Second is fiber count: MPO/MTP connector could provide 4, 6, 8, 12, 24, 36, 64 or more interconnections, among which 12 and 24 are the most popular MPO/MTP connectors. In addition, like other fiber optic connectors, the selection of a MPO/MTP connectors should also consider fiber type and simplex or duplex design.

MPO/MTP Connector is a popular multi-fiber connector for high port density. It can offer ideal solution to set up high-performance data networks with the advantages of time saving and cost saving. As an important technology during migration to 40/100 Gigabit Ethernet, MTP/MPO connector is now being adopted by more and more data centers.

Note: this article is originally published in my blog (http://www.fiber-optic-cable-sale.com/), which is updated weekly. For more pictures in details about this article and knowledge about optical communication, you can follow this blog.

How Much Do You Know About LC Connector

Fiber optic connectors are used to the mechanical and optical means for cross connecting fibers. Fiber optic connectors can also be used to join fiber cables to transmitters or receivers. There have been many types of connectors developed for fiber cable. Single mode networks have used FC or SC connectors in about the same proportion as ST and SC in multimode installations. But LC connector with smaller size and higher performance has become popular and the connector choice for optical transceivers for systems operating at gigabit speeds. The following text gives a detailed introduction of LC connector.

History of LC Connector

LC stands for Lucent Connector, as the LC connector was developed by Lucent Technologies as a response to the need by their primary customers, the telcos, for a small, low insertion loss connector. Then the LC design was standardized in EIA/TIA-604-10 and is offered by other manufacturers.

Advantages of LC Connector

There are solid reasons that the LC is the preferred connector for high-performance network. From the appearance, LC connect is like a mini size of SC connector. LC connector borrows split-sleeve construction and a cylindrical ferrule (usually ceramic) from SC connector. LC connector has a push-and-latch design providing pull-proof stability in system rack mounts. The picture below shows the appearance of SC connector and LC connector.

The ferrule size of LC connector is 1.25 mm which is half the size of SC connector ferrule—2.5 mm. LC connector is rated for 500 mating cycles and its typical insertion loss is 0.25 dB. An interesting feature of the LC is that, in some designs, the ferrule can be “tuned” or rotated with a special tool after it has been assembled. This offers a considerable performance advantage. The design and performance of LC connector address the need for high density and low insertion loss.

Application of LC Connector

LC connector can be found in many places for termination and connection, especially SFP transceivers for gigabit transmission. For example, the optic interfaces of Cisco SFP transceivers are all LC connectors. Some other applications are as following:

• Telecommunication networks
• Local area networks
• Data processing networks
• Cable television
• Fiber-to-the-home
• Premises distribution

LC Connector Selection Guide

To meet the needs of market, there are various types of LC connectors provided now. During the selection of LC connector, transmission media should be the first factor to consider. LC connector favors single mode fiber optic cable. But it can also be used with multimode fiber optic cable. Signals sometimes are transferred over simplex fiber optic cable and sometime duplex fiber optic cable. Thus, LC connector has both simplex and duplex design. The picture above shows an APC simplex LC connector on the left and a UPC duplex LC connector on the right. Some other factors like polishing style (APC or UPC), hole size and cable diameter should not be ignored. For more details about LC connectors, you can visit Fiberstore which provides various LC connectors with high performance and low price.

Note: this article is originally published in my blog (http://www.fiber-optic-cable-sale.com/), which is updated weekly. For more pictures in details about this article and knowledge about optical communication, you can follow this blog.

Introduction of PC, UPC and APC Connector

When we choosing a LC connectors, you might hear descriptions like LC UPC polished fiber optic connector, or LC APC fiber optic connector. Or when you are choosing a ST fiber optic patch cable, you can find the description like ST/PC multimode fiber optic patch cable. What do PC, UPC, APC stand for? The following text will give the explanations.

PC (physical contact), UPC (ultra physical contact) and APC (angle physical contact) are the polish style of ferrules inside the fiber optic connectors. Unlike copper cables with copper wire in the connectors as connection media, fiber optic connectors are with ceramic ferrules for connection. The picture above shows the ferrule in fiber optic connector. Different fiber optic connectors has different ferrule size and length. Also their polish style might be different.

To better understand the why we have PC, UPC and APC, let’s start with the original fiber optic connector which has a flat-surface and is also known as flat connector (showed in the following picture). When two flat fiber connectors are mated, an air gap naturally forms between the two surfaces from small imperfections in the flat surfaces. The back reflection in flat connectors is about -14 dB or roughly 4%. To solve this problem, the PC connectors came into being.

In the PC connector, the two fibers meet, as they do with the flat connector, but the end faces are polished to be slightly curved or spherical. This eliminates the air gap and forces the fibers into contact. The back reflection is about -40 dB. The following picture shows two end faces of PC connectors.

UPC connector, usually has a blue-colored body, is an improvement to the PC connector with a better surface finish (as showed in the following picture) by an extended polishing. The back reflection of UPC connector is about -55 dB which lower than that of a standard PC connector. UPC connectors are often used in digital, CATV and telephony systems.

PC and UPC connectors have reliable, low insertion losses. However, their back reflection depends on the surface finish of the fiber. The better the fiber gain structure, the lower the back reflection. If the PC and UPC connectors are continually mated and remated, back reflection will degrade. An APC connector won’t have such problem. Its back reflection does not degrade with repeated matings.

APC connector usually has a green body with an end-face still curved but are angled at an industry-standard 8 degrees (showed in the above picture) which allows for even tight connections and smaller end-face radii. Thus any light that is redirected back towards the source is actually reflected out into the fiber cladding, again by virtue of the 8 degree angled end-face. APC ferrules offer return losses of -65dB. Some applications that are more sensitive to return loss than others that call for APC connectors, like FTTx and Radio Frequency (RF) applications. APC connectors are also commonly used in passive optical applfications due to the fact that many of these systems also use RF signals to deliver video.

PC, UPC or APC, which should be the choice of fiber optic connector? The answer is it depends. Choosing the appropriate connector for a fiber network depends on things such as, network design and function. This article is originally published in my blog （http://www.fiber-optic-cable-sale.com/）which is update weekly. You can follow this blog for more about optical communication

1000BASE-T—Upgrade Your LAN Over Copper Cable

During the deployment of bandwidth-intensive applications over local area networks (LANs), many factors should be considered, like the speed, the infrastructure, the transmission media, etc. One of the most important things is the cost. Many LANs already use CAT-5 cabling. Replace these cables with fiber optic cable might cost a lot. For some companies which might have tight budgets and must leverage their existing infrastructure, 1000BASE-T would be a nice and cost-effective way to upgrade their LAN.

What is 1000BASE-T?

1000BASE-T is Gigabit Ethernet that provides speeds of 1000 Mbps (1 gigabit is 1000 megabits per second) over four unshielded twisted pairs of cabling rated at Category 5/5e or better. 1000BASE-T specification allows a segment with a maximum length of 100 meters due to signal transmission limits, which can be used in data centers for server switching, LANs, for uplinks from desktop computer switches or directly to the desktop for broadband application. One of the advantages of 1000BASE-T is cost-effective.

A Cost-Effective Solution for Gigabit Ethernet

Fiber optic cables are gradually replacing copper cables in today’s telecommunication network. However, given the high cost of replacing copper cables with fiber optic cables and the low cost and good performances of 1000BASE-T, many companies might choose the 1000BASE-T system to upgrade their network and enjoy Gigabit Ethernet over copper cables. The following text illustrates the reasons why 1000BASE-T is one of the most cost-effective high-speed networking technology available.

• No need to replace copper cables with fiber optic cables—it is known that copper solutions have traditionally been lower than fiber-based solutions. As many companies still use Cat 5 twisted pairs, the replacing of copper into fiber optics will cost a lot of money and time. With the application of 1000BASE-T, companies can upgrades their local area network, data centers, etc. by using their existing copper cable place which would be time-saving and cost-saving.

• No need to change Ethernet equipment and infrastructure investments—if you replace all the copper cables into fiber optic cables, you would be forced to replace cabling located in walls, ceilings, or raised floors. And the equipment connected to the fiber links should also be updated. It would be time-consuming and high-cost task, which won’t be the best choice of some companies with tight budget or lacking of time. With 1000BASE-T, these problems would be solved easily. 1000BASE-T preserves Ethernet equipment and infrastructure investments, including the investment in the installed Category 5 cabling infrastructure.

• Flexible 100/1000 and 10/100/1000 connectivity—1000BASE-T support data rate ranging from 10 Mbps to 1000 Mbps. Flexible 100/1000 and 10/100/1000 connectivity will be offered and will enable the smooth migration of existing 10/1000 networks to 1000 Mbps-based networks. Used in conjunction with 1000BASE-T SFP transceivers, 1000BASE-T can provide highly cost-effective shared gigabit service. Various 1000BASE-T SFP transceiver modules that can enhance the performance of 1000BASE-T systems are being provided by current vendors.

1000BASE-T is a time-saving and cost-effective solution to upgrade the LANs to have Gigabit Ethernet. With the big advantage of cost-effective, 1000BASE-T are being widely applied. As technology advanced, various products are being provided to enhance the 1000BASE-T performances, like 1000BASE-T SFP transceivers. Fiberstore provides a wide range of telecommunication products including 1000BASE-T SFP transceivers and Category 5/5e products. You can visit Fiberstore for more detailed information about 1000BASE-T

Originally published in : http://www.fiber-optic-cable-sale.com/1000base-t-upgrade-your-lan-over-copper-cabling.html

Why Choose Direct Attach Cable in 40G/100G Migration?

Advance technologies like Big Data and Cloud which require high speed of data rate become more and more popular. To meet the ever growing need to high speed data transmission, many data centers are migrating from 10 GbE to 40 GbE or even 100 GbE. And some are considering about the migration, during which the cost is one of the most important factors to consider. Direct attach cable also known as DAC is a cost effective solution during the migration to 40GbE or 100GbE.

What Is Direct Attach Cable

A direct attach cable also known as DAC is usually a fixed assembly supporting high speed data that uses a small form-factor connector module as an optical transceiver on each end of a length of cable. With significant cost-saving and power-saving benefits, direct attach cable is now being widely used in data centers for short reach applications. It can be connected to switches, servers, routers, network work interface cards (NICs), Host Bus adapters (HBAs) providing high density and high data throughput.

Why Choose Direct Attach Cable

Direct attach cable with many significant benefits can satisfy the growing need for high speed data. The main benefits of direct attached cable are described in the following text.

Cost saving: the modules on the end of direct attach cable looks like optical transceivers. However, actually they very much different from optical transceiver. These small form-factor connector modules leave out the expensive optical lasers and some electronic components. That's the main reason why the DAC is much cheaper than optical transceiver. Direct attach cable in some case can be an alternative to optical transceivers as it eliminates the separable interface between transceiver module and optical cable. Thus, choosing DAC in some cases can save a lot of money as well as time.

Low power consumption: to identify the modules on the end and cable type to the Ethernet interface, in both active direct attach cable and passive direct attach cable a small electrical component is used, which is low cost and consumes very little power compared with optical transceiver.

Supporting high data rate: DAC can provide high speed I/O (input and output) data. The most commonly used DAC can support high data rate of 10 Gb/s and 40 Gb/s. However, as technologies advanced, some vendor can provide direct attached cable supporting 120 Gb/s, like 120G CXP Cables.

Meet small form-factor standards: the modules on each end of DAC meet small form-factor standards which means DAC inherits some advantages of the small form-factor module, like space saving. Some time there is no need to upgrade the equipment by using a DAC.

With various benefits like abilities in data transmission and cost saving, direct attach cable is becoming increasingly popular for short distance top-of-rack (ToR) and middle-of row (MoR) data center deployments. It's a cost-effective solution to 40G/100G migration. Currently direct attach cable are continuing to evolve to meet industry needs. Various types of directive attach cable are being provided. Fiberstore as a vendor of optical components provides DAC cable assemblies including 10G SFP+ Cables, 40G QSFP+ Cables, and 120G CXP Cables. For information please visit Fiberstore.

Originally published at: http://www.fiber-optic-cable-sale.com/why-choose-direct-attach-cable-in-40g-100g-migration.html

Optical Transceiver Selection Guide

As an important optical component being widely used in today’s optical network, optical transceiver has been developing rapidly. More and more vendors are providing various types of transceivers to meet the market calls. To select a matching transceiver for a given application and hardware is now an easy thing now. Many parameters should be considered. The following text is to provide the parameters should be considered during the selecting of the proper optical transceivers.

MSA (Multi-Source Agreement) Type

A transceiver is usually used to mechanically and electrically fit into a given switch and router. Transceiver MSAs define mechanical form factors including electric interface as well as power consumption and cable connector types. There are the following types of optical transceivers according to MSA: GBIC, XENPAK, X2, XFP, SNAP12, SFP, QSFP/QSFP+, CXP and CFP.

Protocol and Data Rate

As different switch or router supports different protocol and data rate. Before selecting the transceiver needed, make sure the protocol and data rate to be supported. The following provides the most common protocol and data rate types:

• Gigabit Ethernet: 1 GE/10GE/40GE/100GE
• Fiber Channel: 1GFC (1.25Gbps) / 2GFC / 4GFC / 8GFC / 16GFC
• SDH STM-1 (155Mbps) / STM-4 (622Mbps) / STM-16 (2.5Gbps / STM-64 (10Gbps)
• Multirate (155Mbps to 2.67Gbps)
• CPRI up to 6Gbps (for Video Transmission)

Transport Media

The most commonly used transport media are cooper, single mode fiber (SMF), Multimode fiber (MMF). Maker sure the transport media, before choosing an optical transceiver.

Transceiver “Color”

The colored transceiver commonly known as CWDM transceivers and DWDM transceivers. In CWDM or DWDM system, each channel uses a different “color” transceiver because each lambd represents a different color in the spectrum

Equipment Compatibility

In what switch or router is the transceiver supposed to work. Now the third party transceivers are being provided. If the equipment open for third party transceiver, then the third party transceiver could be an option. However, if not, the brand, model and firmware version must be known.

IEEE Descriptions

The functions of the optical transceivers are various, thus understand the IEEE descriptions of the optical transceivers can help to select the match one quickly. The following provided are the translation of IEEE descriptions:

• MM: multimode
• SM: single mode
• Base -T: “copper” SFP with electrical RJ45 interface
• SX: SFP 850nm, MM, grey, 1GE, approx. 500m
• LX: SFP 1310nm, SM, grey, 1GE, approx. 8km
• EX: SFP 1310nm, SM, grey, 1GE, approx. 40km
• ZX: SFP 1550nm, SM, grey, 1GE, approx. 70km
• CX4: "copper" XFP with electrical IB4x connector
• SR: SFP+ or XFP 850nm, MM, grey, 10GE, approx. 300m
• LR: SFP+ or XFP 1310nm, SM, grey, 10GE, approx. 10km
• ER: SFP+ or XFP 1550nm, SM, grey, 10GE, approx. 40km
• ZR: SFP+ or XFP 1550nm, SM, grey, 10GE, approx. 80km
• SR4: QSFP 850nm, MM, 40GE, approx. 100m
• SR10: CFP 850nm, MM, 100GE, approx. 100m
• LR4: CFP or QSFP 1310nm, SM, 40GE (CFP or QSFP) or 100GE, approx. 10km

Taking the above parameters into consideration, to select a match optical transceiver would be much easier and more quickly. Fiberstore, an professional optical components provider, offers a wide range of optical transceivers of high quality including SFP, SFP+, CWDM transceiver, DWDM transceivers, etc. For more information, you can visit Fiberstore.

Originally published at: http://www.fiber-optic-cable-sale.com/optical-transceiver-selection-guide.html