MTP/MPO Cables—An Ideal Solution for High-Density Cabling

For various reasons, the data quantity transmitted worldwide is growing exponentially and the need for ever-greater bandwidths continues unabated. Though the current data volumes demanded in backbone cabling can still be handled with 10 GbE, the forecast trends will require the introduction of the next technologies, 40 GbE and 100 GbE (Figure 1). Therefore, data centers must respond early to provide sufficient capacities and plan for upcoming requirements. To meet this demand, 40G QSFP+ transceivers, MTP/MPO cables and other related products are springing up like mushrooms in the market. They are important roles in the ultra-high density cabling in data centers. This post will focus on MTP/MPO cables in the data center.

trend over time of Ethernet technologies
Why MTP/MPO Cables Are Used?

For the reasons mentioned above, the number of network connections in data centers is on the rise rapidly. And the use of traditional fiber cables may make the data center crowed and difficult to be managed. To solve this problem, data centers have to achieve ultra-high density in cabling to accommodate all this cabling in the first place. The MTP/MPO cables, which bring together 12 or 24 fibers in a single interface (Figure 2), have been proven to be a practical solution. Incorporating to meet the 40GBASE-SR4 and 100GBASE-SR10 standard, The MTP/MPO multi-fiber connector of MTP/MPO cables is about the same size as a SC connector but can accommodate 12 or 24 fibers. Thus, MTP/MPO cables provide up to 12 or 24 times the density and offer savings in circuit card and rack space.

MPOMTP multi-fiber connectors
Details of MTP/MPO Cables

MTP/MPO cables are composed of MTP/MPO connectors and fiber cables, other connectors such as LC may also be found in some kinds of MTP/MPO cables. And the fiber cables used are generally OM3 and OM4, which are laser optimized multi-mode optical fibers. Unlike traditional connectors, the MTP/MPO connector should be carefully used to ensure proper connections are made. Thus, it is important to have an overall understanding of MTP/MPO connectors.

As is shown in the following figure, each MTP/MPO connector has a key on one side of the connector body, and the key sitting on top 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. People often refer to these connector holes as positions, or P1, P2, etc. In addition, there is a white dot on the connector body to designate the P1 side of the connector when it is plug in.

MPO connector

There are two types of MTP/MPO adapters based on the placement of the key: key up to key down and key up to key up. When you want to connect two MTP/MPO connectors, it is important to choose a right adapter with keying designed to hold the two facing ends of the MTPs incorrect alignment. The following figure shows the right connections of two MTP/MPO connectors within the adapter.

MPOMTP connectors held within the adaptor
Common Types of MTP/MPO Cables

MTP/MPO trunk cable and MTP/MPO harness cable are two common kinds of MTP/MPO cables. MTP/MPO trunk cables serve as a permanent link connecting the MTP/MPO modules to each other. And they can offer flexibility in changing the connector style in the patch panels. MTP/MPO harness cables provide a transition from multi-fiber cables to individual fibers or duplex connectors. These cables are offered for various applications for all networking and device needs like 100G modules including CFP, CFP2 and CFP4 series.

MTP-MPO-Trunk-Cable-&-MTPMPO-Harness-Cable
Conclusion

There is no way around the migration to 40 and 100 GbE. As the figure shows above, 40 and 100 GbE will be broadly introduced in the near future. Therefore, Data center managers will have to lay the groundwork today and adapt their infrastructure to meet future requirements. MTP/MPO cables are inevitable the ideal solution to meet these needs. Fiberstore is now striving to be a leading supplier of MTP/MPO connection components. We manufacture and distribute a wide range of MTP/MPO connection components including the MTP/MPO connectors, adapters, cables, cassettes, adapter panels, loopback modules, etc.

A Copper-based Gigabit Ethernet Solution – 1000BASE-T

Enormous efforts put on the development of high-performance Ethernet technology that provides gigabit-per-second transmission rates have led to the extension of Gigabit products to include the copper Gigabit Ethernet (GbE) standard: 1000BASE-T. Many papers and articles have been attributed to introducing the fiber-optic GbE standards, such as 1000BASE-SX, 1000BASE-LX, 1000BASE-ZX. And contributions are few about 1000BASE-T. This text just helps you to better understand 1000BASE-T and talks about it: a copper GbE solution.

What Is 1000BASE-T Technology?

1000BASE-T is also known as IEEE 802.3ab. Just judging from its name, “1000” here means the transmission speed of 1000Mbps. The “BASE” refers to BASE band signaling, indicating that only Ethernet signals are carried on the medium. The “T” represents twisted-pair copper cable (for example Cat 5). More specifically, 1000BASE-T uses four pairs of Cat 5 unshielded twisted pair (UTP) to achieve the Gigabit data rate and achieves 1000Mbps data rates by sending and receiving a 250Mbps data stream over each of the four pairs simultaneously. The distribution of four-pair Cat 5 cabling extends from the work area to the equipment room and between equipment in the equipment room, thus enabling connectivity to switched and shared gigabit services for both high-bandwidth work area computing and server farms.

four cat 5 UTP pairs

1000BASE-T is able to provide half-duplex (CSMA/CD) and full-duplex 1000Mb/s Ethernet service over Cat 5 links as defined by ANSI/TIA/EIA-568-A. Besides GbE applications over Cat 5 copper cabling, 1000BASE-T also supports other specifications. First, it supports the Ethernet MAC (Media Access Control), and is backward compatible with a 10/100 Mbps Ethernet. Second, many 1000BASE-T products support 100/1000 auto-negotiation, and therefore 1000BASE-T can be incrementally deployed in a Fast Ethernet network. Third, 1000BASE-T is a high-performing technology with less than one erroneous bit in 10 billion transmitted bits. (10 is the same error rate as that of 100BASE-T.) Topology rules for 1000BASE-T are the same as those used for 100BASE-T.

Why Choose This Copper Gigabit Ethernet Solution?

Why network designers choose 1000BASE-T as the copper GbE solutions? Or put it in another way, what are the advantages of 1000BASE-T?

  • Performance—1000BASE-T scales Ethernet 10/100Mbps performance to 1000Mbps. Compared with 1Gbps, 1000BASE-T is 100 times as fast as the standard Ethernet. It permits the smooth migration of the 10/100 networks to 1000 Mbps-based networks. When 1000BASE-T technology is deployed in transceiver modules, these 1000BASE-T SFP transceivers, such as Fiberstore compatible Cisco SFP-GE-T, make shared gigabit service possible and aggregate one gigabit of server support. This Cisco 1000BASE-T SFP supports 1000BASE-T operation in host systems with a compact RJ-45 connector assembly.

SFP-GE-T, Cisco 1000BASE-T SFP

  • Cost—Used in conjunction with Full Duplex Repeaters (FDRs), 1000BASE-T can provide highly cost-effective shared gigabit service. FDRs offer the traditional low-cost shared media operation of repeaters, but when coupled with 1000BASE-T, they offer an easy-to-manage, high-burst rate, shared-media solution capable of supporting both end users and server farms. In such a case, to aggregate one gigabit of server support is possible in a cost-effective way.
Notes on Using 1000BASE-T Products

While realizing a 1000Mb/s data stream over four pairs of Category 5 twisted pair cables meet several challenges may meet several challenges, like signal attenuation, echo, return loss, etc.

  • Attenuation is the signal loss of the cabling from the transmitter to the receiver. Attenuation increases with frequency, so designers are challenged to use the lowest possible frequency range that is consistent with the required data rate.
  • Echo is a by-product of dual-duplex operation, where both the transmit and receive signal occupy the same wire pair. The residual transmitted signal because of the trans-hybrid loss combines with the cabling return loss to produce an unwanted signal referred to here as echo.
  • Return loss is a measure of the amount of power reflected due to cabling impedance mismatches.
Conclusion

1000BASE-T technology is the ideal high-speed solution for these application when 1000BASE-T uplinks from desktop switches to aggregating switches. Many network designers have chosen this copper GbE solution for high network performance in a cost-effective way. Fiberstore supplies many 1000BASE-T SFPs which are fully compatible with major brands, like Cisco GLC-T and SFP-GE-T mentioned above. For more information about 1000BASE-T SFPs, you can visit Fiberstore.

Considering Three Aspects Before Migrating to 40G

The dramatic growth of bandwidth requirements in data centers has led to the worldwide use of higher-performance optical products for network scalability, management, flexibility and reliability. Currently, 10GbE (Gigabit Ethernet) can’t meet the increasing needs of high speed transmission well for such applications as Big Data, cloud and Internet of Things being introduced in many industries. As such, network migration to 40/100G has already been the industry consensus.

But as the cost for 100G is far beyond what most enterprises can afford and the technology for 100G is still not mature enough, 40G has been a better solution for its lower cost and maturer technologies compared to 100G. Nowadays, some manufacturers are battling for the 40G market, which drives down the 40G deployment price, leading to the even wider deployment of 40G infrastructure. When migrating from 10G to 40G, three aspects should be considered: fiber optic transceiver, transmission media, and pre-terminated MPO assemblies.

Fiber Optic Transceiver

For any telecommunication network, fiber optic interconnection is of great importance. Photoelectric conversion is a necessary part in fiber optic network. The function of fiber optic transceiver is photoelectric conversion, which makes it one of the most commonly used components in the data center.

As for 40G transceivers, two different package forms are available: QSFP+ (Quad Small Form-factor Pluggable Plus) and CFP (C Form-factor Pluggable), with the former more widely-used than the latter. A single 40G fiber optic transceiver may not be expensive. But what a medium-sized data center needs is thousands of optical transceivers, meaning a large sum of money to be spent. In such a case, third party transceivers that are compatible with a variety types of switches come into point. They have the same performances that the original brand transceivers have, but cost less money. When selecting 40G compatible transceivers, cost and quality are very important. Choosing the compatible 40G transceivers from Fiberstore can ensure 100% compatibility and interoperability. The picture below shows the testing of Cisco compatible QSFP-40G-SR4 transceivers on a Cisco switch to ensure its compatibility and interoperability.

QSFP-40G-SR4, under test

Transmission Media

Allowing for several situations that may exist, the IEEE 802.3ba specified the different transmission media for 40G links, including the following listed media:

  • 40GBASE-CR4: 40Gb/s Ethernet over copper cable in short transmission distance.
  • 40GBASE-SR4 (eg. QFX-QSFP-40G-SR4): 40Gb/s Ethernet over four short-range multi-mode fiber (MMF) optic cables.
  • 40GBASE-LR4: 40Gb/s Ethernet over four wavelengths carried by a signal long-distance single-mode fiber (SMF) optic cable.

There also exists hybrid cabling solutions for 40G applications, like QSFP to 4SFP+ breakout cabling assembly. Take QSFP-4SFP10G-CU5M for example, this product listed in Fiberstore is the QSFP+ to 4 10GBASE-CU SFP+ passive direct-attach copper transceiver assembly with 5-meter reach.

QSFP to 4SFP+ breakout cabling assembly, for short reach, 5m

Question occurs: fiber optic cable or copper cable, which should be used in 40G migration? Copper is cheaper. But it can only support 40G transmission limited to several meters. SMF supports the longest 40G transmission distance up to 40 km. As for MMF, OM3 and OM4 are suggested to support short distance transmission. The longest distance that OM3 can support for 40G transmission is 100 m. OM4 can support a longest 40G transmission distance of 150 m. The selection of transmission media should depend on the specific applications.

MPO Assemblies for 40G

The IEEE 802.3ba standard also specifies multi-fiber push-on (MPO) connectors for standard-length MMF connectivity. Most of the 40G multi-mode Ethernet transceivers are based on the MPO technology. It is wise to increase fiber optic density by using MPO technology, but a new problem arises. As the fiber number increased, the cabling and splicing difficulty in data center increased. Unlike traditional two-strand fiber connections, MPO connectors cannot be field terminated easily. Thus, most of the data centers choose the pre-terminated MPO assemblies in 40G deployment, which is more reliable and can save more human labor. Before cabling, determine the cabling lengths and customized pre-terminated MPO assemblies with manufacturers would save a lot of time and money.

Conclusion

Using compatible third party transceivers of high quality for 40G links saves a lot of money. Taking specific applications and characteristics of 40G transmission media into consideration can also help you to save cost. Pre-terminated MPO assemblies are necessary for flexible and manageable cabling in 40G deployment. With these information in mind, cost-effective 40G migration is at the corner.

In-depth Understanding of Fiber Optic Cables

The commitment to fiber optic technology has spanned more than 30 years, and nowadays a high level of glass purity, fiber optic cable, has been achieved owing to the continuous research and development. This purity, combined with improved system electronics, enables to transmit digitized light signals over hundreds of kilometers with high performance, offering many advantages in fiber optic systems. This text provides an overview of the construction, categories, and working principles of this fiber optic cable.

Construction of Fiber Optic Cable

Fiber optic cable generally consists of fiver elements : the optic core, optic cladding, a buffer material, a strength material and the outer jacket. Here, much more detailed information is attributive to the optic core and optic cladding which are both made from doped silica (glass).

The Optic Core and Cladding Details

The optic core is the light-carrying element at the center of the cable, and the optic cladding surrounds the optic core. Their combination makes the principle of total internal reflection possible. Besides, a protective acrylate coating then surrounds the cladding. In most cases, the protective coating is a dual layer composition: a soft inner layer that cushions the fiber and allows the coating to be stripped from the glass mechanically, and a harder outer layer that protects the fiber during handling, particularly the cabling, installation, and termination processes. This coating protects the glass from dust and scratches that can affect fiber strength.

Optic Core and Cladding, makes reflection possible

Categories of Fiber Optic Cable

There are two general categories of fiber optic cable: single-mode fiber (SMF) and multi-mode fiber (MMF).

MMF was the first type of fiber to be commercialized. It has a core of 50 to 62.5 µm in diameter much larger than SMF, allowing hundreds of modes of light to propagate through the fiber simultaneously. Additionally, the larger core diameter of MMF facilitates the use of lower-cost optical transmitters (such as light emitting diodes or vertical cavity surface emitting lasers) and connectors, more suitable for relatively shorter-reach application. Take 1 Gigabit Ethernet (GbE) applications for example, MMF is deployed to establish 550m link length with 1000BASE-SX SFPs (eg. Cisco Meraki MA-SFP-1GB-SX).

SMF, in contrast, has a much smaller core, approximately 8 to 10 µm in diameter, which allows only one mode of light at a time to propagate through the core. It’s designed to maintain spatial and spectral integrity of each optical signal over longer distances, permitting more information to be transmitted. Similarly, as for 1GbE applications, SMF is able to realize 70km reach with 1000BASE-ZX SFPs, like GLC-ZX-SM, a product compatible with Cisco listed in Fiberstore.

GLC-ZX-SM, 1000BASE-ZX SFP

Working Principles of Fiber Optic Cable

The operation of a fiber optic cable is based on the principle of total internal reflection. Light reflects (bounces back) or refracts (alters its direction while penetrating a different medium), depending on the angle at which it strikes a surface.

This principle comes at the center of how fiber optic cable works. Controlling the angle at which the lightwaves are transmitted makes it possible to control how efficiently they reach their destination. Lightwaves are guided through the core of the fiber optic cable in much the same way that radio frequency (RF) signals are guided through coaxial cable. The lightwaves are guided to the other end of the fiber being reflected within the core. The composition of the cladding glass related to the core glass determines the fiber’s ability to reflect light. That reflection is usually caused by creating a higher refractive index in the core of the glass instead of in the surrounding cladding glass, creating a waveguide. The refractive index of the core is increased by slightly modifying the composition of the core glass, generally by adding small amounts of a dopant. Alternatively, the waveguide can be created by reducing the refractive index of the cladding using different dopants.

Conclusion

In fiber optic cables, the light can carry more information over longer distances than the amount carried in a copper or coaxial medium or radio frequencies through a wireless medium. With few transmission losses, low interference, and high bandwidth, fiber optic cables are the ideal transmission medium. Fiberstore offers various kinds of fiber optic cables, including SMF and MMF types, simplex and duplex fiber optic cables, indoor distribution cables and outdoor loose tube cables, etc. For more information about fiber optic cables, you can visit Fiberstore.

Overview of 40/100GbE Terminations

Today’s data centers growth is placing increasing demands on the networking infrastructure. For some enterprises, existing 1GbE connections can’t support the growing business requirements well very, not to say 100Mbps connections. In order to accommodate these demands, it’s imperative to upgrade the data center network architecture to 40 or 100 Gigabit Ethernet (GbE) connections. This 40/100GbE network design helps to support not only the current growth, but also the increasing demands in the future.

IEEE 802.3ba 40G and 100G Standard

The Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group is concerned with the maintenance and extension of the Ethernet data communications standard. And 802.3ba is the designation given to the higher speed Ethernet task force to modify the 802.3 standard to support higher speeds than 10Gbit/s, that is 40/100G in 2010. This 802.3ba 40/100G standard encompasses a number of different Ethernet physical layer (PHY) specifications which are supported by means of pluggable modules, like Quad Small-Form-Factor Pluggable (QSFP) and C Form-Factor Pluggable (CFP). As for transmission medium, the transport speeds at 40/100Gbit/s use two methods: parallel optics and copper cables, with the fiber optics solutions allowing more flexibility and greater distance reach.

40GbE Terminations

In most cases, 40GbE connections use a QSFP+ transceiver terminated to receive the multi-fiber push-on/multiplex pass-through (MPO/MPT) trunk. That is, the short-range QSFP+ transceivers (eg. QFX-QSFP-40G-SR4) use multi-mode MPO trunks to establish 40G links. During this link establishment, polarity becomes a consideration when implementing 40GbE switch-to-switch interconnects over multi-strand multi-mode fiber (MMF). Method B polarity is recommended for the functional link.

QSFP+ transceivers are also able to run on single-mode fiber (SMF) for long reach. These links are Little Connector (LC) terminated and can run up to 40km, mainly used for 40GbE interbuilding connections. Take QSFP-40G-ER4 for example, this 40GBASE-ER4 transceiver supports link lengths up to 40km over SMF with duplex LC connectors.

The QSFP+ transceiver can also be used for 40GbE to 4x10GbE partitioned applications, that is QSFP+ to 4SFP+ fan-out cabling assemblies. One end of the connection is terminated using a MPO/MPT configuration with four individual pairs terminated with LC connectors at the other end. The image below just shows the QSFP+ to 4SFP+ Active Optic Cable (AOC) assembly.

QSFP+ to 4SFP+ AOC, 40GbE to 4x10GbE partitioned application

100GbE Terminations

100GbE connections use a CFP transceiver. Two CFP options are dominant in the industry: CFP2 and CFP4. The primary differences between the two are physical density and transmit/receive lane configurations. More specifically, CFP2 supports 100GBASE-SR10, 100BASE-LR4, and 100GBASE-ER4 optical interfaces, while CFP4 doubles the port density on the line card and supports 100GBASE-SR4, 100GBASE-LR4, and 100GBASE-ER4 optical interfaces.

CFP options, for 100G transmission

40/100GbE Termination Benefits

The 40/100GbE network infrastructure provides the following benefits:

  • Reduced data center complexity: As virtualization increases, the use of fewer physical servers and switches has been made possible by 40/100GbE network infrastructure.
  • Reduced total cost: Since 40/100GbE network system simplifies the local area network (LAN) and cable infrastructures, the potential cost reduction in virtualization environment is also accessible. Besides, the 40/100GbE network infrastructure requires fewer data center space, power, and cooling resources.
  • Increased Productivity: Faster connections and reduced network latency provide network designers with faster workload completion times and improved productivity.

Upgrading network architecture to support speeds greater than 10GbE, that is 40/100GbE, is essential in optimizing data center infrastructure, giving a hand in moving quickly in respond to business needs. At the same time, the services and value brought by information technology itself can also be enhanced.

Conclusion

The high-performance 40/100GbE network architecture simplifies the cabling infrastructure and reduces per-server total cost of ownership, capable of allowing high speeds at 40/100Gbit/s. Fiberstore offers a large selection of 40/100G optical modules, as well as 40/100G fiber optic-based cables and copper cables. For more information about 40/100GbE solutions, you can visit Fiberstore.

Single Fiber – Why Choose it for Gigabit Optical Communications?

Advanced applications, including voice and data convergence, as well as storage area networking, are putting burdens on today’s fiber optic networking infrastructure, especially on the fiber cabling. With speeds in data centers now increasing from 10Gbps to 40Gbps, to 100Gbps, and 120Gbps, etc., different fiber technologies are required for Gigabit optical communications, like single strand fiber (simplex fiber cable) and duplex fiber cable. This text mainly introduces the single strand fiber, a relatively simple solution chosen for fiber optimization, and its benefits that drive the need to deploy single strand fiber for Gigabit optical communications.

Single Fiber Technologies

Single strand fiber, just as its name shows, uses one strand of glass instead of two dedicated strands with one for receiving and the other for transmitting. It doubles the capacity of the installed fiber plant, which in turn doubles the per fiber return on investment (ROI) with no need for more physical fiber.

Early single fiber solutions were based on single wavelength directional coupler technologies. With these solutions, the same wavelength (1310nm for up to 50km or 1550nm for longer distances) travels in each direction (transmit & receive). At the edges, the two signals are coupled into a single fiber strand with a directional coupler (splitter-combiner). This coupler identifies the direction of the two signals (ingress or egress) and separates or combines them. This kind of solution is normally very reliable and cost effective, as long as special installation and connector type (APC -angle polished connector) requirements are observed. Otherwise, this solution is prone to reflections when traversing patch panels and in the cases of fiber cuts or dirty connectors.

single fiber 1310nm TX/1510nm Rx

In recent years, a new single strand fiber technology has emerged based on two wavelengths traveling in opposite directions. External WDM couplers (multiplexers) combine or separate the two wavelengths at the edges. As technology progressed, the external passive WDM coupler became integrated into a standard interface fixed optic transceiver.

Single Fiber SFP (Small Form Pluggable)

The growing demand of single fiber solutions driven by the Ethernet bandwidth has led to the development of a wide range of single fiber pluggable SFP transceivers. These hot-pluggable optic transceivers are designed in small-form factor for high-density solutions, covering many industrial protocols and allowing flexibility in distance choices. Besides, they provide advanced optical performance, Digital Diagnostics Monitoring (DDM). Commonly-used single SFPs include 1000BASE-LX SFPs (eg.EX-SFP-1GE-LX shown below), 1000BASE-ZX SFPs, etc.

EX-SFP-1GE-LX,single fiber SFP

Single Fiber Benefits

The benefits of the single strand versus the dual strand fiber implementation can be considerable.

  • Operational and Capital Expense Savings

Single fiber solutions, like any other fiber optimization methods, affect both the capital expenses (CAPEX) and the operational expenses (OPEX). For fiber users like carriers and enterprises that lease dark fiber from their provider rather than owning the fiber plant, the OPEX savings is extremely significant by avoiding avoid the need to install additional fiber strands to accommodate growth without imposing limitations due to engineering capabilities.

  • Fiber Run — Engineering Cost

The design and engineering of a fiber run is a complex process. It may require crossing roads or freeways, which leads to possible thorough design, and inflexible work scheduling. The deployment cost might include trenching or other expenses. In many cases, the price of labor, services, and licenses required to install new cabling can far exceed the cost of the media and supporting electronics.

  • Fiber Termination and Accessories Cost

New fiber runs require terminating and connecting any fiber strand. This process requires qualified labor that will polish, connectorize, and test every fiber strand. Reducing the number of terminated fiber strands by half results in a significant cost reduction.

  • Network Reliability and Maintenance Cost

Reliability and availability are key in any communications system. Use of single fiber pluggable-based transceivers in an existing dual fiber link opens the possibility of creating redundant link solutions. In fiber assembly, a larger number of fiber strands increase the chance of fiber failure. The larger the fiber strands are, the higher the failure chances are, thus the maintenance cost increase accordingly. This can be reduced through the simplicity of single fiber technology.

Conclusion

Single fibers are considered as the simple way for fiber optimization, for they not only double the capacity of the installed fiber plant, but also help to achieve overall savings in Gigabit optical communications. Fiberstore offers single fibers available in both single-mode and multi-mode versions, which are all quality assured. In addition, single fiber optical transceivers can also be found in Fiberstore, such as 1000BASE-LX SFP (EX-SFP-1GE-LX mentioned above), 10GBASE-ZR SFP+ (SFP-10G-ZR). For more information about single fibers, you can visit Fiberstore.

FAQs About Laser-Optimized Fiber

Fiber optical networks have dominated for long-haul communications for years, increasingly used in short distance applications, such as local area networks (LANs). And the Ethernet data-rate needed for these high-performance fiber optic networks increases from 1Gbps to 10Gbps, to 40Gbps, to 100Gbps, or even higher. Together with this speed increase, a term, laser-optimized fiber, has crept into the telecommunication market. What is laser-optimized fiber? How much do you know about it? Knowing answers to these frequently asked questions (FAQs) about laser-optimized fiber will help you prepare for the latest wave in optical communication networks.

FAQ 1: What Is Laser-Optimized Fiber?

Laser-optimized multi-mode fiber (LOMMF: OM3 & OM4) differs from standard MMF (OM1 & OM2), because the former has graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances up to 300 meters (OM3) and 400 meters (OM4) at 10Gbps, while OM1 and OM2 can only realize 26 meters and 33 meters link length respectively at the same data rate. And when 1000BASE-SX SFP transceivers transmit and receive signals over LOMMF and standard MMF at 1Gbps, the possible link lengths achieved are also different, with OM1 275-meter reach, OM2, OM3, and OM4 up to 550-meter reach. Take MGBSX1 for example, this compatible Cisco 1000BASE-SX SFP listed in Fiberstore supports up to 550-meter link length over OM2.

MGBSX1, 550m link length over MMF

FAQ 2: Why Have MMF Been “Optimized” for Use with Lasers?

As the demand for bandwidth and higher throughput increased, especially in building and campus backbones, LEDs, short for Light Emitting Diodes, that are used as light sources in fiber optic systems could not keep pace. With a maximum modulation rate of 622Mb/s, LEDs would not support the 1 Gb/s and greater transmission rates required. The use of traditional lasers (Fabry-Perot, Distributed Feedback) typically used over single-mode fiber (SMF) could accommodate this problem. However, it’s very expensive due to the higher performance characteristics required for long-distance transmission on SMF. As such, a high-speed laser light source, a Vertical Cavity Surface Emitting Laser (VCSEL) was developed. These VCSELs are inexpensive, suited for low-cost 850nm multi-mode transmission systems, allowing for data rates up to 100Gbps in the enterprise. With the emergence of these VCSELs, MMFs have been “optimized” for operation with lasers.

FAQ 3: Why Are LOMMFs the Best Choice for Use with VCSELs?

After VCSELs appears, to fully capitalize on the benefits that VCSELs offer, LOMMFs have been specifically designed, fabricated, and tested for efficient and reliable use with VCSELs.

LOMMF,specifically designed, fabricated, and tested

LOMMFs have a well-designed and carefully controlled refractive index profile to ensure optimum light transmission with a VCSEL. Precise control of the refractive index profile minimizes the modal dispersion, also known as Differential Mode Delay (DMD). This ensures that all modes, or light paths in the fiber arrive at the receiver at about the same time, minimizing pulse spreading and, therefore, maximizing bandwidth.

LOMMF is completely compatible with LEDs and other fiber optic applications. LOMMFs can be installed at slower data rates or higher data rate. When there occurs the data rate migration from 10Gbps to 40Gbps, there is no need to pull new cable. You only need to upgrade the optics modules to VCSEL-based transceivers, avoiding infrastructure redesign.

Conclusion

LOMMFs are the suitable medium for short-wave 10G optical transmission. Their great bandwidth- and information-carrying capacity make them more popular among consumers than standard MMFs especially in 10GbE systems. Fiberstore supplies countless OM3 and OM4, as well as OM1 and OM2 for your network projects. Besides, other kinds of fiber optic cables, like MTP cable and SMF, are also available in Fiberstore. For more information about fiber optic cables, please visit Fiberstore.

Pluggable Transceivers Used in Data Centers

Today’s data centers are going through unprecedented growth and innovation as emerging optical standards and customers’ demands for higher-level networking services converge. Bandwidth, port density and low-power demands come as the main drivers that populate the deployment of fiber optic networks. And in fiber optic network implementations, pluggable transceivers provide a modular approach to safe-proof network design and become the ideal choice to meet the ever-changing network needs in data centers. This text just mainly introduces pluggable transceivers deployed in data centers.

A Quick Question: What Are Pluggable Transceivers?

Pluggable transceivers are transceivers that can be plugged into routers, switches, transport gear, or pretty much any network device to transmit and receive signals. They are hot swappable while the device is operating, standardized to be interchangeable among vendors, capable of operating over many different physical medium and at different distances. For instance, pluggable transceivers can work through copper, through fiber optic cables available in both single-mode fibers (SMFs) and multi-mode fibers (MMFs), realizing 100m, 300m, 10km, 80km distance reach, etc. In addition, these hot-swappable transceivers are also able to support a wide variety of speeds, like 1Gbit/s, 10Gbit/s, 40Gbit/s, 100Gbit/s, or even higher.

Pluggable Transceiver – Standards & Protocols

Just as what has been mentioned above, pluggable transceivers are interchangeable. These interchangeable transceivers allow a single device to operate with a wide selection of protocols and functions. Listed below are commonly-used pluggable transceiver standards and protocols.

SFP—The small form-factor pluggable (SFP) supports a wide range of protocols and rates, such as Fast and Gigabit Ethernet (GbE), Fibre Channel (FC), and synchronous optical networking (SONET) for dual and bidirectional transmission. SFP medium are available in SMF, MMF, and copper. For MMF media, there exists 1000BASE-SX port type used in 1GbE applications. Take J4858C for example, this HP 1000BASE-SX SFP can realize a maximum of 550m reach at 1.25 Gbit/s over MMF.

J4858C, HP 1000BASE-SX SFP

SFP+—The enhanced small form-factor pluggable (SFP+) is an enhanced version of the SFP, supporting data rates up to 16Gbit/s. It was first published on May 9, 2006, and version 4.1 was published on July 6, 2009, supporting 8Gbit/s FC, 10GbE and Optical Transport Network standard OTU2. SFP+ is a popular industry format supported by many network component vendors.

XFP—The XFP (10G SFP) is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. Its principal applications include 10GbE, 10Gbit/s FC, SONET at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s Optical Transport Network (OTN) OTU-2, and parallel optics links.

QSFP—The Quad Small Form-factor Pluggable (QSFP) is a also a compact, hot-pluggable transceiver used for data communications applications. QSFP+ transceivers are designed to carry Serial Attached SCSI, 40GbE (100G using QSFP28), QDR (40G) and FDR (56G) Infiniband, and other communications standards. They increase the port-density by 3x-4x compared to SFP+ modules. In 40GbE applications, these QSFP+ transceivers establish 40G links with distances up to 300m over MMF, and 40km over SMF. QSFP can also take copper as its media option when the required distance is short. Like QSFP-4SFP10G-CU5M, this product is the QSFP to 4 10GBASE-CU SFP+ direct attach passive copper cable assembly designed for relatively short reach, that is 5m. The image below just shows what this QSFP-4SFP10G-CU5M product looks like.

QSFP-4SFP10G-CU5M, QSFP to 4 10GBASE-CU SFP+

CFP—The C form-factor pluggable (CFP) is a multi-source agreement (MSA) to produce a common form-factor for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 100 Gigabit Ethernet systems.

Conclusion

Pluggable transceivers offer distance extension solutions, allowing flexibility in network reach and easy replacement in the event of component failures. They are the answer to today’s network architecture and performance demands. Fiberstore supplies various pluggable transceivers supporting different speeds, like SFP (J4858C), SFP+, XFP, QSFP, CFP, etc. Additionally, their transmission medium available in fiber and copper can also be found in Fiberstore. For more information about pluggable transceivers, you can visit Fiberstore.

Three Media Options for 10GbE in Data Centers

With the added network infrastructure complexity, power demands, and cost considerations, 10 Gigabit Ethernet (GbE) comes to network administrators’ thinking point. While 1GbE connection is able to handle the bandwidth requirements of a single traffic type, 10GbE has been preferred as the ideal solution by customers to meet current and future input/output (I/O) demands. Delivering more bandwidth, 10GbE simplifies the network infrastructure at the same time by consolidating multiple gigabit ports into a single 10gigabit connection.

Generally speaking, there are three media options for 10GbE: 10GBASE-CX4, SFP+, and 10GBASE-T. Each option has its own virtual point and downside in terms of cost, power consumption and distance reach. This paper analyzes these three options respectively, helping you understanding the pros and cons of current 10GbE media options.

10GBASE-CX4

10GBASE-CX4 was the first 10G copper standard published by 802.3 (as 802.3ak-2004), an early favorite standard for 10GbE deployments. Using the XAUI 4-lane PCS (Clause 48) and copper cabling similar to that used by InfiniBand technology, 10GBASE-CX4 is able to reach 15 meters. Practically, this option is limited by its heavy weight and expensive cables. In addition, the size of the CX4 connector prohibited higher switch densities required for large scale deployment. Larger diameter cables are purchased in fixed lengths, causing problems in managing cable slack. What’s more, the space isn’t sufficient to handle the larger cables.

10GBASE SFP+

SFP+ fiber optic cables and SFP+ direct attach cables (DACs) are all better solution than CX4.

10GBASE SFP+ Fiber Optic Cables

10GBASE-SR, 10GBASE-LR, 10GBASE-LRM are all specified to work through fiber optic cables, such as JD094B (shown below). This HP 10GBASE-LR SFP+ transceivers takes fiber as its transmission medium with distance up to 10km. Really, great for latency and distance, but fibers are expensive. Although they offer low power consumption, the project of laying fiber networks in data centers is limited due to the cost of the electronics largely. The fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is also more expensive.

JD094B, HP 10GBASE-LR SFP+ transceiver

10GBASE SFP+ DAC

DAC can be classified in to direct attach copper cable and active optic cable (AOC). On the one hand, SFP+ DAC is a lower cost option alternative to fiber, with its distance reaching flexible in 1m (eg. SFP-10G-AOC1M), 2m, 3m, 5m, 7m and so on. On the other, SFP+ DAC is not backward-compatible with existing 1GbE switches. Besides, this solution requires the purchase of an adapter card and requires a new top of rack (ToR) switch topology. And the cables are much more expensive than structured copper channels, and cannot be field terminated. All these factors make SFP+ DAC less popular the 10GBASE-T which will be discussed soon.SFP-10G-AOC1M, for short reach

10GBASE-T

10GBASE-T, or IEEE 802.3an-2006, is a standard released in 2006 to provide 10Gbit/s connections over unshielded or shielded twisted pair cables with distances up to 100metres (330 ft). Due to additional encoding overhead, 10GBASE-T has a slightly higher latency in comparison to most other 10GBASE standards. What’s more, 10GBASE-T offers the most flexibility, the lowest cost media. And because of its backward-compatibility with 1000BASE-T, 10GBASE-T can be deployed based on existing 1GbE switch infrastructures that are cabled with CAT6 and CAT6A (or above) cabling, keeping costs down while offering an easy migration path from 1GbE to 10GbE.

Conclusion

The deployment of 10GbE infrastructure should be much easier, with these media options in mind, coupled with your own such project considerations as cost, power consumption and distance reach. Fiberstore, as a professional fiber optic product supplier, offers a broad selection of fiber and copper cables, including SFP-10G-AOC1M mentioned above. For more information about 10GbE media options, you can visit Fiberstore.

CAT5 – Copper Network Solutions Choice

Defined by the Electronic Industries Association and Telecommunications Industry Association (commonly known as EIA/TIA), CAT5 (Category 5) cable is the copper wiring using twisted pair technology, designed for Ethernet networks. The term “Category” refers to the classifications of UTP (unshielded twisted pair) cables. Since its inception in the 1990s, CAT5 has become one of the most popular types of of all twisted pair cable types which include CAT3, CAT4, CAT5, CAT6, etc. This article details CAT5 used in copper networks from its working principles, its standard, as well as its installation considerations.

How CAT5 Cable Technology Works

CAT5 is widely used in 100BASE-TX and 1000BASE-T Ethernet networks. CAT5 typically contains four pairs of copper wire. In 100BASE-TX standard, the signals are transmitted across only two of the CAT5 pairs. One pair is used to transmit signals, and the second pair receives the signals, leaving the other two unused in signal transmission. What’s more, the 100BASE-TX signals only run in one direction across the pairs. As technology advanced, the 1000BASE-T Gigabit Ethernet (GbE) standard was developed. 1000BASE-T standard utilizes all four copper pairs to transmit up to 250 megabits of data per second (Mbps) in full duplex transmission across each pair. That is to say, each pair is able to transmit and receive signals simultaneously. 1000BASE-T modules (eg. GLC-T) functioning over CAT 5 with RJ-45 connector achieve full duplex transmission with link length up to 100m (328ft).

GLC-T, functions over CAT 5 with RJ-45 connector

There are two standards for CAT5 wiring, EIA/TIA-568A and EIA/TIA-568B. The following passages mainly discuss EIA/TIA-568A.

EIA/TIA-568A

The TIA-EIA-568-A standard defined the following three main parameters for testing Category 5 cabling installations: wiremap, attenuation, and Near End Crosstalk (NEXT).

Wiremap is a continuity test. It assures that the conductors that make up the four twisted pairs in the cable are continuous from the termination point of one end of the link to the other. This test assures that the conductors are terminated correctly at each end and that none of the conductor pairs are crossed or short-circuited.

Attenuation is the loss of signal, as it is transmitted from the end of the cable to the opposite end at which it is received. Attenuation, also referred to as Insertion Loss, is measured in decibels (dB). For attenuation, the lower the dB value is, the better the performance is, and of course less signal is lost. This attenuation is typically caused by absorption, reflection, diffusion, scattering, deflection.

Near End Crosstalk (NEXT) measures the amount of signal coupled from one pair to another within the cable caused by radiation emission at the transmitting end.If the crosstalk is great enough, it will interfere with signals received across the circuit. Crosstalk is measured in dB. The higher the dB value, the better the performance, more of the signal is transmitted and less is lost due to coupling.

NEXT: the amount of signal coupled from one pair to another

CAT5 Installation Considerations

After testing parameters are mentioned above, here goes the notes of CAT 5 installation.

  • Never pull CAT5 copper wire with excessive force. The CAT5 tension limitation is 25 lbs, much lower than standard audio/video cable.
  • Never step on, crush, or crimp CAT5.
  • Avoid periodic sags; vary the intervals if the cable must sag.
  • Do not bend CAT5 wire tightly around a corner; ensure that it bends gradually, so that a whole circle would be at least two inches in diameter.
  • Do not allow knots or kinks, even temporarily.
  • Never run CAT5 parallel to power wiring closer than six inches.
  • Avoid splices. Every splice degrades the line.
Conclusion

Although CAT5 is superseded by CAT5e in many applications, most CAT5 cable meets Cat5e standards and it’s still a commonplace in Local Area Networks (LANs). Many copper networks choose CAT5 as their transmission media because of its low price and high performance. Fiberstore supplies many CAT5 RJ45 pluggable modules, like 100BASE-TX, and 1000BASE-T transceivers (eg. SFP-GE-T). For more information about copper network solutions, you can visit Fiberstore.

Transceivers – How They Help Support Big Data in Data Centers?

Today’s data centers need to better adapt to virtualized workloads and the ongoing enterprise transition to hybrid clouds, since business owners always rely on big date technology to get timely information and make immediate decisions. Transceivers, one of the most critical designs in telecommunication field, are related to the promotion of big data in data centers, helping business owners get their data in real-time. This just explains the importance of being aware of the three ways in which transceivers help support big data in data centers.

Transceivers Facilitate High Speed Data Transfers

A growing number of enterprises are transiting to private and hybrid clouds, which drives the bandwidth and connectivity requirements. As high-speed data carrier, transceivers facilitate high speed data transfers. Enterprises that want to achieve faster transmission have to choose transceivers with high quality. There are many types of transceivers available in the market, such as SFP, SFP+, XFP, QSFP, etc. Each type of transceiver is designed to support different data rate. Capable of transmitting data at 10Gbit/s, 40Gbit/s, 100Gbit/s or even 120 Gbit/s, transceivers can realize the high-speed data transfer, ensuring bandwidth upgrades in enterprise data centers. Take 10GBASE SFP+ modules for example, these hot-pluggable transceivers (eg.SFP-10G-SR) deployed for 10 Gigabit Ethernet (GbE) applications, though designed physically small, can handle fast transmission with the maximum data rate of 10.3125Gbps.

SFP-10G-SR, handles fast transmission

Transceivers Promote Data Transmission Process in Data Centers

Enterprise that need to manage big data can benefit from the use of transceivers. Data centers are places where enterprises store the barrage of data that comes from their offices. The information is usually stored in the cloud where employees and executives have access to the information in determining the actions they need to make in their organizations. The data centers need to transmit data accurately, securely, and rapidly. Transceiver technology can promote the data transmission process in data centers.

Transceivers Promote Data Transmission Process in Data Centers

Transceivers Support Big Data in Data Centers

Data centers have experienced the exponential growth as the demand for big data increases. Greater bandwidth is necessary to support many applications, like video download, live online show, and other types of data. Transceivers are a necessity in ensuring that the data is transmitted securely, expeditiously, and accurately via the fiber. Transceivers are used in conjunction with multiplexers and switches. When they work together, managing network capacity becomes an easy task.

Additionally, transceivers also have a role in companies’ sales. It’s known that big data can be accessible on mobile devices through the cloud. Transceivers are capable of facilitating the transmission from wireless cell tower base stations. Company employees like salesmen are always on-the-go to make sales, and to have access to information is really important. When they are able to obtain valuable information from the mobile devices which record the data, they can make decisions faster, thus more apt to make a sale for their companies.

Transceiver technology increases the speed of data transmission through the fiber deployed by enterprises in data centers. Executives can make faster decisions and maintain a competitive advantage when they have access to getting information timely. Transceivers help to support big data in data centers, and play a really important role in executives’ decision-making process. Without the use of transceivers, it’s impossible to transmit data at high speed over significant distances.

Conclusion

It’s necessary to mention that there are more than three ways that transceivers help support big data in data centers. Only three popular ways are discussed in this article. Transceivers, a key component designed in relation to the promotion of big data in data centers, are instrumental in managing big data. Fiberstore, as a professional transceiver supplier, several types of transceivers supporting different data rates, like SFP+ (SFP-10G-SR mentioned above), XFP (eg. XFP-10G-MM-SR), QSFP, etc. You can visit Fiberstore for more information about transceivers with high quality and competitive prices.

Guide to Coaxial Cable, Twisted Pair Cable and Fiber Optic Cable

The advancements of cable-based technologies have made wider accessibility to greater bandwidth possible in Local Area Network (LAN). With so many network options, to select a right cable-based solution for broadband connection services is a little confusing. When such factors as cost, speed, bandwidth and immunity are considered, which one is an ideal choice for networks, coaxial cable or twisted pair cable? Or is the fiber optic cable that meets your needs?

Coaxial Cable

Coaxial cable, or  in a foam insulation, symmetrically surrounded by a woven braided metal shield, then covered in a plastic jacket. Because of its insulating property, coaxial cable can carry analogy signals with a wide range of frequencies. Thus it is widely used in feedlines connecting radio transmitters and receivers with their antennas, computer network connections, digital audio, and distributing cable television signals. The following figure shows the structure of coaxial cable.

Coaxial cable, a single wire usually copper wrapped

Actually, there exists another cable, twin-ax cable, which is similar to coaxial cable, but with two inner conductors instead of one. This kind of cable comes in either an active or passive twin-ax (twin-axial) cable assembly, used for 10, 40 or 100 Gigabit Ethernet (GbE) links.Like QSFP-H40G-CU1M, this Cisco 40G cabling product is the QSFP to QSFP passive copper cable assembly designed for high-performance 40GbE networks.

QSFP-H40G-CU1M, QSFP to QSFP passive copper cable assembly

Twisted Pair Cable

Twisted pair cable is a type of wiring in which two conductors of a single circuit are twisted together. It comes in two versions: Shielded Twisted Pair (STP) and Unshielded Twisted Pair (UTP). STP is commonly used in Token Ring networks and UTP is in Ethernet networks. The image below displays what UTP (left) and STP (right) look like.

Twisted pair cable, UTP and STP

Fiber Optic Cable

A fiber optic cable is a cable containing one or more optical fibers. Fiber optic cables often contain several silica cores, and each fiber can accommodate many wavelengths (or channels), allowing fiber to accommodate ever-increasing data capacity requirements. When terminated with LC/SC/ST/FC/MTRJ/MU/SMA connectors on both ends, such as LC-LC, LC-SC, LC-ST, SC-ST, SC-SC, ST-ST etc, fiber optic cables can achieve fiber link connection between equipment.

Comparison of Three Kinds of Cables

Coaxial cable can be installed easily, relatively resistant to interference. However, it is bulky and just ideal for short length because of its high attenuation. It would be expensive over long-distance data transmission. By contrast, twisted pair cable is the most flexible and cheapest among three kinds of cables, easy to install and operate. But it also encounters attenuation problem and offers relatively low bandwidth. In addition, it is susceptible to interference and noises. As one of the most popular mediums for both new cabling installations and upgrades, including backbone, horizontal, and even desktop applications, fiber optic cable is small in size and light in weight. Because the conductor is glass which means that no electricity can flow through, fiber cable is immune to electromagnetic interference. The biggest advantage of fiber optic cable is that it can transmit a big amount of data with low loss at high speed over long distance. Nevertheless, it needs complicated installing skills, difficult to work with and expensive in the short run.

When selecting which kind of cable is appropriate for network services, one should keep in mind that each cable has its unique advantages and disadvantages concerning about these factors: cost, speed, security, reliability, bandwidth, data carrying-capacity, and so on.

Conclusion

Choosing among coaxial cable, twin-ax cable, twisted pair cable and fiber optic cable depends on your needs. You can balance the cost and the requirements of bandwidth to make a choice. In Fiberstore, you can find twisted pair cables and a series of fiber optic cables. Other cables, such as active optical cable (AOC) (eg. QSFP-4X10G-AOC10M) are also available for your networks. You can visit Fiberstore for more information about cable-based solutions.

Interfaces for 40 GbE Architecture in Data Centers II

In the previous post “Interfaces for 40 GbE Architecture in Data Centers I”, we generally learned about the Chip-to-chip port side interface in the 40 Gigabit Ethernet architecture. And in this post, we will continue to learn the interfaces used for 40 Gigabit Ethernet. This article will focuses on the Chip-to-module direct attach interface.

Chip-to-module direct attach interface

A chip-to-module interface consists of a short PCB trace and a module connector between a port side IC and a module that is without retiming capability.

To increase the port densities to achieve the higher required bandwidth in chassis, the signal conditioning function was moved from inside of a 10 Gigabit pluggable module, such as XFI, to the port side interfaces. As a result, a new high-speed 10 GE serial electrical interface called SerDes Framer Interface (SFI) was defined by SFF MSA. SFI is applied for an interface between a host ASIC and the small form-factor pluggable module, SFP+ (the follwing picture shows the connection methods).

connection methods of chip to module

SFI is defined for both limiting and linear mode modules. In the limiting mode, SFI supports PHY connections to the limiting SFP+ optical transceivers, such as 10GBASE-SR optics(MMF 300m), 10GBASE-LR optics(SMF 10km), and 10GBASE-ER optics(SMF 40km). In the linear SPI interface, stronger signal conditioning capabilities are required to compensate for electrical dispersion. The linear SPI interface can be used with 10GBASE-LRM optics, and also the passive Direct Attached Copper (DAC) in the length from 1m to 7m, such as QSFP-H40G-CU5M DAC and EX-QSFP-40GE-DAC-50CM DAC.

To improve the port side densities in a chassis, the new XLPPI (40 Gbps Parallel Physical Interface) electrical specification was defined by IEEE 802.3. Another reason for the development of XLPPI is to address the incompatibility between the XLAUI and the QSFP+ module. Therefore, XLPPI is an interface with high port-density, supporting a direct connection to a Quad Small Form Factor Pluggable (QSFP or QSFP+) module (e.g. Brocade QSFP+ and Finisar QSFP+) without the necessity of a re-timer function.

Compared with XLAUI interfaces, XLPPI Interface is defined in 802.3ba Annex 86a as the interface between the PMA and PMD functions (where as the XLAUI dissects the PMA). The XLPPI is derived from the SFI interface and places higher signal integrity requirements on the host PMA than the XFI based XLAUI.

XLPPI is the electrical specification to both passive copper based 40GBASE-CR4 QSFP+ module and the optical modules such as the short reach 40GBASE-SR4 optical transceiver and 40GBASE-LR4 optical transceiver. Therefore, currently QSFP+ modules with XLPPI interfaces support 40GBase-CR4 (both passive and active) cables and 40GBase-SR4 (either AOC or using the MPO/MTP®connector) cables.

40G Transceivers: CFP, QSFP and CXP

In fiber optic communication, 40GbE transceivers are being developed along several standard form factors, such as CFP (C form-factor pluggable) transceiver, QSFP/QSFP+ (quad small-form-factor pluggable) transceiver and CXP optical transceiver. This article will introduce the three types of optical transceivers to further your understanding of 40G optics.

CFP Transceiver

CFP, short for C form-factor pluggable, is compliant with multi-source agreement (MSA) to produce a common form-factor for the transmission of high-speed digital signals. The C in the acronym “CFP” stands for the Latin letter C, which refers to the number 100 (centum), since the standard was primarily designed for 100 Gigabit Ethernet systems. In fact, CFP also supports the 40GbE. When talking about CFP, we always define it as multipurpose CFP.

CFP

The CFP form factor, defined in the MSA, supports both singlemode and multimode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces contained in the IEEE 802.3ba Task Force. At 40GbE, target optical interfaces include the 40GBase-SR4 for 100 m and the 40GBase-LR4 for 10 km. There are three PMDs for 100 GbE: 100GBase-SR10 for 100 m, 100GBase-LR4 for 10 km, and 100GBase-ER4 for 40 km.

QSFP/QSFP+ Transceiver

QSFP/QSFP+ transceiver (Quad Small Form-factor Pluggable Plus) is a wildly used transceiver interfaces in data communications, connecting a network device motherboard (e.g. a switch, router, media converter and the like) with a fiber optic cable. It is a industry format that is jointly developed and supported by many network component vendors, such as Dell QSFP+, Juniper QSFP+, Mellanox QSFP+ and HP QSFP+. Additionally, QSFP supports both copper and optical cabling solutions.

Compared with the CXP, the QSFP (quad small-form-factor pluggable) is similar in size (shown as the following picture). It provides four transmitting and four receiving lanes to support 40GbE applications for multimode fiber and copper today and may serve single-mode in the future. Another future role for the QSFP may be to serve 100GE when lane rates increase to 25Gb/s.

QSFP-CXP

CXP Transceiver

“C” in the acronym CXP represents for 12 in hex, and the Roman number “X” means that each channel has a transmission rate of 10 Gbps. “P” refers to pluggable that supports the hot swap. Thus, CXP is a hot-pluggable transceiver with data rate up to 12×10 Gbps.

CXP is developed for the clustering and high-speed computing markets, so we also call it high-density CXP. the CFP is able to work with multimode fiber for short-reach applications, but it is not really optimized in size for the multimode fiber market, most notably because the multimode fiber market requires high faceplate density. The CXP was created to satisfy the high-density requirements of the data center. It is featured with the parallel interconnections for 12x QDR InfiniBand (120 Gbps), 100 GbE, and proprietary links between systems collocated in the same facility.

As stated above, these 40G optics have been very popular in the market, and they are able to keep the momentum in the future for 100G transmission.

Which One Will You Choose for FTTx? PON or AON?

When it comes to FTTx deployment, there are two competing network solutions which are PON (Passive Optical Network) and AON (Active Optical Network). What is the difference between them? And which one will you choose? PON or AON? You may find the answer from the following contents.

PON-AON

PON

A PON consists of an optical line terminator (OLT) located at the Central Office (CO) and a set of associated optical network terminals (ONT) to terminate the fiber–usually located at the customer’s premise. Both devices require power. Instead of using powered electronics in the outside plant, PON uses passive splitters and couplers to divide up the bandwidth among the end users–typically 32 over a maximum distance of 10-20km.

AON

An active optical system uses electrically powered switching equipment to manage signal distribution and direct signals to specific customers. This switch opens and closes in various ways to direct the incoming and outgoing signals to the proper place. Thus, a subscriber can have a dedicated fiber running to his or her house. Active networks can serve a virtually unlimited number of subscribers over an 80km distance.

Advantages and Disadvantages of PON
  • Advantages PON has some distinct advantages. It’s efficient, in that each fiber optic strand can serve up to 32 users. Compared to AON, PON has a lower building cost and lower maintenance costs. Because there are few moving or electrical parts and things don’t easily go wrong in a PON.
  • Disadvantages PON also has some disadvantages. One of the biggest disadvantages is that these splitters have no intelligence, and therefore cannot be managed. Then you can’t check for problems cost-effectively when a service outage occurs. Another major disadvantage is its inflexibility. If one needs to re-design the network or pull a new strand of fiber from the upstream splitter, all downstream customers must come offline for changing the splitter in the network. At last, since PONs are shared networks, every subscriber gets the same bandwidth. So data transmission speed may slow down during peak usage times.
Advantages and Disadvantages of AON
  • Advantages AON offers some advantages, as well. First, its reliance on Ethernet technology makes interoperability among vendors easy. Subscribers can select hardware that delivers an appropriate data transmission rate and scale up as their needs increase without having to restructure the network. Second, it’s about the distance. An active network has the distance limitation of 80 km regardless of the number of subscribers being served. At last, there are some other advantages like high flexibility for deploying different services to residential and business customers, and low subscriber cost.
  • Disadvantages Like PON, AON also has its weaknesses. It needs at least one switch aggregator for every 48 subscribers. Because it requires power, AON inherently is less reliable than PON.

From the above contents, you can find that both technologies have its advantages and disadvantages. In some cases, FTTx systems actually combine elements of both passive and active architectures to form a hybrid system. Thus, to decide which technology to deploy, you should consider your own unique circumstances.

Originally published at www.china-cable-suppliers.com/pon-or-aon-for-fttx.html

Why Does FTTH Develop So Rapidly?

FTTH (Fiber to the Home) is a form of fiber optic communication delivery in which the optical fiber reached the end users home or office space from the local exchange (service provider). FTTH was first introduced in 1999 and Japan was the first country to launch a major FTTH program. Now the deployment of FTTH is increasing rapidly. There are more than 100 million consumers use direct fiber optic connections worldwide. Why does FTTH develop so rapidly?

FTTH is a reliable and efficient technology which holds many advantages such as high bandwidth, low cost, fast speed and so on. This is why it is so popular with people and develops so rapidly. Now, let’s take a look at its advantages in the following.

FTTH

  • The most important benefit to FTTH is that it delivers high bandwidth and is a reliable and efficient technology. In a network, bandwidth is the ability to carry information. The more bandwidth, the more information can be carried in a given amount of time. Experts from FTTH Council say that FTTH is the only technology to meet consumers’ high bandwidth demands.
  • Even though FTTH can provide the greatly enhanced bandwidth, the cost is not very high. According to the FTTH Council, cable companies spent $84 billion to pass almost 100 million households a decade ago with lower bandwidth and lower reliability. But it costs much less in today’s dollars to wire these households with FTTH technology.
  • FTTH can provide faster connection speeds and larger carrying capacity than twisted pair conductors. For example, a single copper pair conductor can only carry six phone calls, while a single fiber pair can carry more than 2.5 million phone calls simultaneously. More and more companies from different business areas are installing it in thousands of locations all over the world.
  • FTTH is also the only technology that can handle the futuristic internet uses when 3D “holographic” high-definition television and games (products already in use in industry, and on the drawing boards at big consumer electronics firms) will be in everyday use in households around the world. Think 20 to 30 Gigabits per second in a decade. No current technologies can reach this purpose.
  • The FTTH broadband connection will bring about the creation of new products as they open new possibilities for data transmission rate. Just as some items that now may seem very common were not even on the drawing board 5 or 10 years ago, such as mobile video, iPods, HDTV, telemedicine, remote pet monitoring and thousands of other products. FTTH broadband connections will inspire new products and services and could open entire new sectors in the business world, experts at the FTTH Council say.
  • FTTH broadband connections will also allow consumers to “bundle” their communications services. For example, a consumer could receive telephone, video, audio, television and just about any other kind of digital data stream using a simple FTTH broadband connection. This arrangement would more cost-effective and simpler than receiving those services via different lines.

As the demand for broadband capacity continues to grow, it’s likely governments and private developers will do more to bring FTTH broadband connections to more homes. According to a report, Asian countries tend to outpace the rest of the world in FTTH market penetration. Because governments of Asia Pacific countries have made FTTH broadband connections an important strategic consideration in building their infrastructure. South Korea, one of Asian countries, is a world leader with more than 31 percent of its households boasting FTTH broadband connections. Other countries like Japan, the United States, and some western countries are also building their FTTH broadband connections network largely. It’s an inevitable trend that FTTH will continue to grow worldwide.

Originally published at www.china-cable-suppliers.com/why-does-ftth-develop-so-rapidly

Fiber Optic Connector Cleaning

With the deployment of 40G and 100G systems in the data center, reliable and efficient fiber installations are critical to the high performance network. Contaminated fiber optic connectors can often lead to degraded performance. Any contamination on the fiber connectors can cause failure of the component or failure of the whole system. So it’s important to keep fiber connectors clean.

Contamination Sources

There are two most important forms of contamination on fiber connectors and they are oils and dust. Oils from human hands will leave a noticeable defect easily seen with a fiberscope. The oil will trap dust against the fiber and bring scratches to the fiber connector. Inserting and removing a fiber can create a small static charge on the ends, which can attract airborne dust particles. Simply removing and re-inserting a fiber may also contaminate the end of the connector with a higher level of dust. Fiber caps, which are used to prevent fiber ends from being contaminated while not seated in a connector, will collect dust, dirt, oil and other contaminants to the fiber when used. Except oil and dust, there also other types of contamination, such as film residues condensed from vapors in the air, powdery coatings leaving after water or other solvents evaporating away. These contaminates tend to more difficult to remove and can also cause damage to equipment if not removed.

Contamination Inspection Tools

To inspect whether a fiber connector is contaminated, one should use fiberscope, clean and resealable container for the endcaps, bulkhead probe. A fiberscope is a customized microscope for inspecting optical fiber components. The fiberscope should provide at least 200x total magnification. The bulkhead probe is a handheld fiberscope used in order to inspect connectors in a bulkhead, backplane, or receptacle port. It should provide at least 200x total magnification displayed on a video monitor.

Contamination Inspection Steps

With contamination inspection tools, you should know how to inspect fiber connectors. The following introduces the inspection steps:

  • Make sure that the lasers are turned off before you begin the inspection. Be careful: Invisible laser radiation might be emitted from disconnected fibers or connectors. Do not stare into beams or view directly with optical instruments.
  • Remove the protective cap and store it in a clean resealable container. Verify the style of connector you inspect and put the appropriate inspection adapter or probe on your equipment.
  • Insert the fiber connector into the fiberscope adapter, and adjust the focus ring so that you see a clear endface image. Or, place the tip of the handheld probe into the bulkhead connector and adjust the focus.
  • On the video monitor, see if there is contamination present on the connector endface (See the following figure).

clean-connector-and-connectors-with-contamination

Connector Cleaning Tools

If there is contamination inspected on the fiber connector, then you need to clean it with proper tools. These tools can be divided into four types based on the cleaning method.

fiber-optic-cleaner-one-click

  • Wet cleaning: Optic cleaning with a solvent.
  • Non-Abrasive cleaning: Cleaning without abrasive material touching the fiber optic connector end face.
  • Abrasive cleaning: The popular lint free wipes, such as fiber optic mini foam swabs.
Connector Cleaning Steps

How to clean the fiber connector? Here is about the cleaning steps with abrasive cleaning tools.

  • Gently wipe endface with lint-free pad in one direction.
  • Using a can with compressed gas held upright and approximately 2 inches from the connector end, release a stream of gas on the connector endface for no more than 5 seconds.
  • Gently wipe the ferrule and the end-face surface of the connector with an alcohol pad. Making sure the pad makes full contact with the end-face surface. Wait 5 seconds for the surface to dry.

After finishing the cleaning steps, you should better inspect again to make sure there is definitely no contamination on the connector. Remember never touch the end face of the fiber connector and always install dust caps on unplugged fiber connectors. Do not re-use optic cleaning swabs or lens paper (lint free wipes).

Originally published at http://www.china-cable-suppliers.com/fiber-optic-connector-cleaning.html

Understanding of Optical Losses for Better Data Transmission

When light propagates as a guided wave in a fiber core, it experiences some power losses. These are particularly important for signal transmission through fiber optic cables over long distance. For better telecommunication, we should try to decrease optical losses. Then first we need to know well about optical losses. The article will tell about intrinsic fiber losses and extrinsic fiber losses.

Intrinsic Fiber Losses

Intrinsic fiber losses are those associated with the fiber optic material itself. There are two kinds: scattering losses and absorption losses (see the following picture). Light is attenuated mainly because of these.

absorption-scattering

  • Absorption Losses Absorption loss is caused by absorption of photons within the fiber such as metal ions (e.g., Cu2+, Fe3+) and hydroxyl (OH–) ions. Optical power is absorbed in the excitation of molecular vibrations of such impurities in the glass. One absorption feature is that it occurs only in the vicinity of definite wavelengths corresponding to the natural oscillation frequencies or their harmonics of the particular material. In modern fibers, absorption losses are almost entirely cuased by OH–1 ions. The fundamental vibration mode of these ions corresponds to l = 2.73 µm and the harmonics at 1.37 and 0.95 µm. To reduce presence of OH1 ions, it’s possible to employ dehydration.
  • Scattering Losses Scattering losses are the second dominat influence factor to the signal attenucation in an optical fiber. This kind of loss is caused by micro variations in the fiber material density, which occur during the manufacturing process. Even though the careful manufacturing techniques is advanced and careful, most fibers are still inhomogeneous with disordered and amorphous structures. The scattering losses decrease in porption to the fourth power of the signal wavelength. So the scattering loss is a dominant loss mechanism below wavelengths of 1,000 nm. It’s also necessary in the third transmission window at the wavelengths of 1,550 nm.
Extrinsic Fiber Losses

These losses are specific to geometry and handling of the fibers and are not functions of the fiber material itself. There are two basic kinds and they are bending losses and connector losses.

  • Bending Losses When optical fiber cables are bent, they exhibit additional propagation losses. This is called bending losses which is a frequently encountered problem in fiber optics. Typically, these losses rise very quickly once a certain critical bend radius is reached. This critical radius can be very small (a few millimeters) for fibers with robust guiding characteristics (high numerical aperture), or it can be much larger (often tens of centimeters) for single-mode fibers. Losses are greater for bends with smaller radius.bending-attenuation
  • Connector Losses Connector losses are related to the coupling of the output of one fiber with the input of another fiber, or couplings with detectors or other components. The losses may arise in fiber connectors and splices of the joined fibers with cores of different diameters or misaligned centers. Or the losses may occur if fibers’ axes are titled. The losses caused by mismatching of fiber diameters can be approximated by –10 log(d/D). There are other connection losses such as offsets or air gaps between fibers, and poor surface finishes.

From this article, you may know something about optical losses. To get better data transmission, you should consider the above influence factors. For intrinsic fiber losses, the products’ material is critical. For extrinsic fiber losses, note that you should try to avoid bending the fiber and do good coupling of fibers, joining fibers with the same diameters, avoid the fiber axes titled, etc.

Article source: http://www.china-cable-suppliers.com/understanding-of-optical-losses-for-better-data-transmission.html

Fiber Optic Splicing

Fiber optic splicing is one of the fiber optic terminations which creates a permanent joint between the two fibers. With the benefits of low light loss and back reflection, fiber optic splicing is a preferred method when the cable runs are too long for a single length of fiber or then joining two different types of cables together. There are two methods of splicing, fusion splicing and mechanical splicing.

Fusion Splicing

In fusion splicing (as following picture), a machine called fusion splicer is used to precisely align the two fiber ends. Then the glass ends are “fused” or “welded” together using some type of heat or electric arc. This produces a permanent connection between the fibers enabling very low loss light transmission (Typical loss: 0.1 dB). Fusion splicing has the best return loss performance of all the mating and splicing techniques.

fusion-splice

Fusion Splicing Steps
    • Prepare the fiber. Strip the protective coatings, jackets, tubes, strength members, etc. and only leave the bare fiber showing. Please pay attention to keep the fiber clean.
    • Cleave the fiber. Choose a good fiber cleaver. The cleaved end must be mirror-smooth and perpendicular to the fiber axis to obtain a proper splice. But the cleaver is not used to cut the fiber. It’s only used to produce a cleaved end that is as perpendicular as possible.
    • Fuse the fiber. Align the fusion splicer unit and use an electrical arc to melt the fibers, permanently welding the two fiber ends together. Alignment can be manual or automatic.
    • Protect the fiber – To ensure the splice not break during normal handling, you must protect the fiber from bending and tensile forces. A typical fusion splice has a tensile strength between 0.5 and 1.5 lbs and will not break during normal handling but it still requires protection from excessive bending and pulling forces.
Mechanical Splicing

Mechanical splicing (as following picture) aligns and mates the end face of two cleaned and cleaved fiber tip together. It’s a reusable splice. The mechanical splice will have an index matching fluid that eliminates the fiber-to-air interface, there by resulting in less back reflections. Mechanical splices are often used when splices need to be made quickly and easily.

mechanical-splicing

Mechanical Splicing Steps
  • Prepare the fiber. Strip the protective coatings, jackets, tubes, strength members, etc. and only leave the bare fiber showing. Please pay attention to keep the fiber clean.
  • Cleave the fiber. This one is the same to the fusion splicing step. But the cleave precision is as critical.
  • Mechanically join the fibers. This method doesn’t use heat. Simply put the fiber ends together inside the mechanical splice unit. The index matching fluid inside the mechanical splice apparatus will help couple the light from one fiber end to the other. Older apparatus will have an epoxy rather than the index matching fluid holding the cores together.
  • Protect the fiber – the completed mechanical splice provides its own protection for the splice.
Which One Should You Choose?

To decide which fiber splicing method you should choose, you may take two important factors into consideration. First, it’s the cost. Mechanical splicing has a low initial investment ($1,000—$2,000) but costs more per splice ($12-$40 each). While the initial investment is about at least $15,000 and per splice cost is about $0.50 – $1.50. Second, it’s the performance. Fusion splicing offers a high degree performance of lower loss and less back reflection than mechanical splicing.

By the comparison of the cost and performance of two methods, now you know which one is suitable for your applications. If you have enough money and need more precise alignment for lower loss, you could buy a fusion splicing machine. If you just have a small budget and should make a quick splice, then you can choose mechanical fiber optic splice.

Originally published at http://www.china-cable-suppliers.com/fiber-optic-splicing.html

How Does Fiber Connector Polish Type Influence Termination?

Connectors are used to mate two fibers to create a temporary joint and/or connect the fiber to a piece of network device. That’s one of fiber termination ways. The primary specification of connector termination is loss or the amount of light lost in the connection. Connector loss can be caused by a number of factors. This article will talk about the influence of fiber connector polish type on connector termination.

fiber-connector-termination

When the cone of light emerges from the connector, it will spill over the core of the receiving fiber and be lost. In addition, the end gaps can arouse the other problem called reflectance. The air gap in the joint between the fibers causes a reflection when the light encounters the change of refractive index from the glass fiber to the air in the gap. This reflection is called to as reflectance or optical return loss, which can be a problem in laser based systems.

Nowadays the fiber optic connectors have several different ferrule shapes or finishes, usually referred to as end finish or polish types. The connector end face preparation will determine the connectors’ return loss, also known as back reflection. Different end face causes different back reflection.

PC Polish

The Physical Contact (PC) polish results in a slightly curved connector surface, forcing the fiber ends of mating connector pairs into physical contact with each other. This eliminates the fiber-to-air interface and results in back reflections of -30 to -40 dB. The PC polish is the most popular connector end face, used in most applications.

UPC Polish

In the Ultra PC (UPC) polish, an extended polishing cycle enhances the surface quality of the connector, resulting in back reflections of -40 to -55 dB and < -55dB, respectively. These polish types are used in high-speed, digital fiber optic transmission systems.

APC Polish

Later, it was determined that polishing the connector ferrules to a convex end face would produce an even better connection. The convex ferrule guaranteed the fiber cores were in contact. Losses were under 0.3dB and reflectance -40 dB or better. This solution is to angle the end of the ferrule 8 degrees to create APC or angled PC connector. Then any reflected light is at an angle that is absorbed in the cladding of the fiber, resulting in reflectance  of >-60 dB.

FC-APC-Connector

As the introduction of fiber optic technology, numerous connector styles have been developed – probably over 100 designs. Each connector style is designed to offer better performance (less light loss and reflectance) and easier, faster and/or more inexpensive termination. For example, FC–“Ferrule Connector”. The following are three common types of FC connectors:

  • FC/PC–It’s the most common of the FC connectors. The tip is slightly curved to ensure only the fiber cores make connection during mating not the ferrules themselves. The return loss is 25-40 dB.
  • FC/UPC–The higher quality polish with rounder edges than FC/PC ensures better core mating. The return loss is 45-50 dB. It can mate with FC/PC connectors.
  • FC/APC–Common in most single mode applications where back reflection is critical to be minimized. Identified by the 8 degree of angle present in the ferrule tip along with a typical green colored strain relief boot. The return loss is 55-70 dB. It can only mate with other FC/APC fibers.

From this article, you can see the connector with APC polish type can provide the best connection. Later when you face many different types of fiber optic connectors, you may take polish type as one of the factors to make your decision.

Article source: http://www.china-cable-suppliers.com/how-does-fiber-connector-polish-type-influence-termination.html