Author: Fiber-MART.COM

Proper selection of fiber optic cables and connectors for specific uses is becoming more and more important as fiber optic systems become the transmission medium for communications and aircraft applications, and even antenna links. Choices must be made in selecting fiber optic cables and connectors for high-reliability applications. This article provides the knowledge for how to make appropriate selections of fiber optic cable and connector when designing a fiber optic system.

Fiber Optic Cable Selection

To select a fiber optic cable, you have to make choices of both the fiber selection and the cable construction selection.

Fiber Selection

The three major fiber parameters used in selecting the proper fiber for an application are bandwidth, attenuation and core diameter.

Bandwidth: The bandwidth at a specified wavelength represents the highest sinusoidal light modulation frequency that can be transmitted through a length of fiber with an optical signal power loss equal to 50 percent of the zero modulation frequency component. The bandwidth is expressed in megahertz over a kilometer length (MHz/km).

Attenuation: The optical attenuation denotes the amount of optical power lost due to absorption and scattering of optical radiation at a specified wavelength in a length of fiber. It is expressed as an attenuation in decibels of optical power per kilometer (dB/km). The attenuation is determined by launching a narrow spectral band of light into the full length of fiber and measuring the transmitted intensity.

Core Diameter: The fiber core is the central region of an optical fiber whose refractive index is higher than that of the fiber cladding. Various core diameters are available to permit the most efficient coupling of light from commercially available light sources, such as laser diodes. There are two basic fiber types, single-mode and multimode. Single-mode fiber has a core diameter of 8 to 10 microns and is normally used for long distance requirements and high-bandwidth applications. Multimode fiber has a core diameter of 50 or 62.5 microns and is usually used in buildings. The picture below shows single-mode and multimode fiber with different core diameters.

Cable Construction Selection

Another important consideration when specifying optical fiber cable is the cable construction. There are three main types of cable configurations: buffered fiber cable, simplex cable and multichannel cable.

Buffered Fiber Cable: There are two kinds of buffered fiber. The first is a loose buffer tube construction where the fiber is contained in a water-blocked polymer tube that has an inner diameter considerably larger than the fiber itself. The loose buffer tube construction offers lower cable attenuation from a given fiber, and a high level of isolation from external forces. Loose buffer cables are typically used in outdoor applications and can accommodate the changes in external conditions. The second is a tight buffer tube design. A thick buffer coating is placed directly on the fiber. The tight buffer construction permits smaller, lighter weight designs and generally yields a more flexible cable. A comparison of these two cable constructions is shown below.

Simplex Cable: A simplex fiber optic cable has only one tight buffered optical fiber inside the cable jackets. Simplex fiber optic cables are typically categorized as interconnect cables and are used to make interconnections in front of the patch panel. They are designed for production termination where consistency and uniformity are vital for fast and efficient operation.

Multichannel Cable: Building multiple fibers into one cable creates a multichannel cable. This type of cable is usually built with either a central or external strength member and fiber bundled around or within the strength member. An external jacket is used to keep the cable together.

40GBASE QSFP+ (quad small form factor pluggable) portfolio offers customers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options for data center, high-performance computing networks, enterprise core and distribution layers, etc. And each kind of 40GBASE QSFP+ transceiver has its special applications. 40GBASE-LR4 QSFP+ transceiver is a common 40 Gigabit Ethernet connectivity option. Here is some basic information about 40GBASE-LR4 QSFP+ transceiver.

Introduction

40GBASE-LR4 QSFP+ module supports link lengths of up to 10 kilometers over a standard pair of G.652 single-mode fiber with duplex LC connectors. The 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device. The letter “L” stands for long, the “R” denotes the type of interface with 64B/66B encoding and the numeral 4 indicates numeral 4 indicates that the transmission is carried out over a ribbon fiber with four singlemode fibers in every direction. Each lane has a 10 Gbit/s data rate. 40GBASE-LR4 QSFP+ transceiver modules are compliant with the QSFP+ MSA and IEEE 802.3ba 40GBASE-LR4. The picture below shows a Mellanox MC2210511-LR4 compatible 40GBASE-LR4 QSFP+ transceiver.

Two Types of 40GBASE-LR4 QSFP+ Transceiver

There are mainly two of 40GBASE-LR4 QSFP+ transceivers, 40GBASE-LR4 CWDM (coarse wavelength division multiplexing) QSFP+ transceiver and 40GBASE-LR4 PSM (parallel single-mode fiber) QSFP+ transceiver. This part mainly talks about these two 40GBASE-LR4 QSFP+ transceiver types.

40GBASE-LR4 CWDM QSFP+ transceiver, such as QSFP-40GE-LR4, contains a duplex LC connector for the optical interface. It can support transmission distance of up to 10km. A 40GBASE-LR4 CWDM QSFP+ transceiver converts 4 inputs channels of 10G electrical data to 4 CWDM optical signals by a driven 4-wavelength distributed feedback (DFB) laser array, and multiplexes them into a single channel for 40G optical transmission. Then the receiver module accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths.

40GBASE-LR4 PSM QSFP+ transceiver is a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It also offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G. The transmitter module accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver module converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels.

Applications

QSFP-40GE-LR4 supports 40GBASE Ethernet rate only, whereas the QSFP-40G-LR4 supports OTU3 data rate in addition to 40GBASE Ethernet rate. 40GBASE-LR4 QSFP+ transceivers are most commonly deployed between data-center or IXP sites with single mode fiber.

Fiberstore offers customers a wide variety of 40GBASE-LR4 QSFP+ transceivers for your high-density and low-power 40 Gigabit Ethernet connectivity options, including 40GBASE-LR4 CWDM QSFP+ transceiver and 40GBASE-LR4 PSM QSFP+ transceiver, like Cisco QSFP-40GE-LR4 40GBASE-LR4 QSFP+ transceiver. Fiberstore also provides wide brand compatible 40G QSFP+ transceivers, such as Brocade QSFP+, Dell QSFP+, Juniper QSFP+, Mellanox QSFP+, and HP QSFP+. Each fiber optic transceiver provided by Fiberstore has been tested to ensure its compatibility and interoperability. Please rest assured to buy.

With the growing demand for high data rates, 40 Gigabit Ethernet (GbE) is now becoming more and more widely adopted. For a 40 GbE network application, precise connectivity is crucial. 40G QSFP (quad small form factor pluggable) portfolio offers customers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options. Among them, 40GBASE-SR4 QSFP+ transceiver is a common 40 GbE connectivity option. And here are some things that you need to know about 40GBASE-SR4 QSFP+ transceivers.

Introduction

40GBASE-SR4 is a fiber optic interface for multimode fiber of OM classes 3 and 4 with four parallel OM3 or OM4 fibers in both directions. “S” means short, indicating that it is an interface for short distances. The “R” denotes the type of interface with 64B/66B encoding and the numeral 4 indicates that the transmission is carried out over a ribbon fiber with four multimode fibers in every direction. Each lane has a 10 Gbit/s data rate. 40GBASE-SR4 QSFP+ modules usually use a parallel multimode fiber (MMF) link to achieve 40G. It offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G over 100 meters of OM3 MMF or 150 meters of OM4 MMF. It primarily enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber female connectors.

40GBASE-SR4 QSFP+ module can also be used in a 4x10G mode for interoperability with 10GBASE-SR interfaces up to 100 and 150 meters on OM3 and OM4 fibers, respectively. The worry-free 4x10G mode operation is enabled by the optimization of the transmit and receive optical characteristics to prevent receiver overload or unnecessary triggering of alarm thresholds on the 10GBASE-SR receiver, and at the same time is completely interoperable with all standard 40GBASE-SR4 interfaces. The 4x10G connectivity is achieved using an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 40GBASE-SR4 module to four 10GBASE-SR optical interfaces. The picture below shows a Mellanox MC2210411-SR4 compatible 40GBASE-SR4 QSFP+ transceiver.

40GBASE-CSR4 QSFP+ module is similar to the 40GBASE-SR4 interface extends supported link lengths to 300m and 400m respectively on laser-optimized OM3 and OM4 multimode fiber cables. Each 10-gigabit lane of this module is compliant to IEEE 10GBASE-SR specifications. This module can be used for native 40G optical links over 12-fiber ribbon cables with MPO/MTP connectors, or in 4x10G mode with ribbon to duplex fiber breakout cables for connectivity to four 10GBASE-SR interfaces. Maximum channel insertion loss allowed is respectively 2.6dB over 300m of OM3 cable or 2.9dB over 400m of OM4 cable.

Conclusion

Fiberstore offers you a wide variety of 40GBASE-SR4 QSFP+ transceivers for your high-density and low-power 40 Gigabit Ethernet connectivity options branded by many famous companies like Cisco, Juniper or HP. And we also provide other compatible 40G QSFP+ transceivers, such as 40GBASE-LR4 QSFP+ transceiver, 40GBASE-ER4 QSFP+ transceiver, 40GBASE-CSR4 QSFP+ transceiver, etc. Every fiber optic transceiver provided by Fiberstore has been tested to ensure its compatibility and interoperability. You can buy from us with confidence.

As a result of data center consolidation, server virtualization, and new applications that require higher data transport rates, 10Gbps infrastructure is becoming overwhelmed by today’s data center requirements, making the shift to 40 and 100 Gbps inevitable, especially in the network aggregation layer and core. How to upgrade the cabling infrastructure and migrate to the 40Gbps era in a cost-effective way? Cisco 40G QSFP (quad small form-factor pluggable) bidirectional (BiDi) technology provides a feasible and effective method, which will be introduced in the following text.

What Is 40G QSFP BiDi Transceiver?

Cisco’s innovative 40 Gbps QSFP BiDi transceiver is a pluggable optical transceiver with a duplex LC connector interface for short-reach data communication and interconnect applications. The Cisco BiDi transceiver supports link lengths of 100m and 150m on laser-optimized OM3 and OM4 multimode fibers. It complies with the QSFP MSA specification, enabling customers to use it on all QSFP 40 Gbps platforms to achieve high-density 40 Gigabit Ethernet networks.

How Does 40G QSFP BiDi Transceiver Work?

Cisco QSFP BiDi transceiver technology converts four channels each of 10Gbps transmit and receive signals to two bidirectional channels of 20Gbps signals, which means that the Cisco QSFP BiDi transceiver has two 20Gbps channels, each transmitted and received simultaneously over two wavelengths on a single MMF strand. The technology uses specialized, multilayer, thin-film dielectric coating and lensing, which allows components to both pass and reflect optical signals at the same time. And it uses Bidirectional Optical Sub-Assembly (BOSA) technology to support two wavelengths (20 Gbps total) on each fiber. The connection can reach 100 meters on OM3 MMF or 150 meters on OM4 MMF, which is the same as 40Gbps SR4. Picture below shows the technology concept of the Cisco QSFP BiDi transceiver.

Why Choose 40Gbps QSFP BiDi Transceiver?

The Cisco QSFP BiDi transceiver transmits full-duplex 40Gbps traffic over one dual-fiber LC connector OM3 or OM4 MMF cable. It provides the capability to reuse 10Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40Gbps connectivity without making great changes to the previous 10Gbps fiber cable plant. By using the existing 10 Gigabit Ethernet duplex multi-mode fiber (MMF) infrastructure for 40 Gigabit Ethernet, the Cisco BiDi transceiver offers significant cost savings and simplifies data center upgrading. It allows for zero-cost fiber migration by reusing the current 10Gbps cabling for 40Gbps device connectivity. 40Gbps QSFP BiDi transceiver reduces overall costs and installation time for customers migrating data center aggregation links to 40Gbps connections. Using Cisco BiDi transceivers offers 75% less fiber and MPO requirements, reduced cable sprawl and rack footprints, and investment protection with future support for 100 Gbps over duplex fiber.

Conclusion

Cisco 40G QSFP BiDi technology removes 40Gbps cabling cost barriers for migration from 10Gbps to 40Gbps connectivity in data center networks. It is quite a competitive option among all those various choices for 40 Gigabit Ethernet applications, such as QSFP+ transceiver, QSFP+ breakout cable or active optical cable. Compared with them, Cisco 40G QSFP BiDi transceivers provide simpler and less expensive 40Gbps connectivity compared to other 40Gbps transceiver solutions. Anyway, you choose the most appropriate one for your applications.

As the quest for greater bandwidth continues and fibre optic connections within data centres and optic fibre networks increase, these challenges must be met by choosing the right type of connectivity. This is all driven by requirements for additional switching and routing, storage, virtualization, convergence, video-on-demand (VoD) and high performance cloud computing. All of these applications plus other bandwidth intensive applications increase the need for transmission speed and data volume over short distances.

Optic fibre 10G transmission systems are becoming more widely used and accepted and migration paths to 40G and 100G have been specified for optical fibre.

The IEEE 802.3ba 40G / 100G Ethernet standard provides guidance for 40G / 100G transmission with multimode fibre. OM3 and OM4 are the only multimode fibres included in the standard.

Parallel optics technology has become the transmission option of choice in many data centres and labs as it is able to support 10G, 40G, and 100G transmission. For parallel optics to work effectively, it requires the right choice of cable and connector.

Parallel optic interfaces differ from traditional fiber optic communication in that data is simultaneously transmitted and received over multiple optical fibres. In traditional (serial) optical communication, a transceiver on each end of the link contains one transmitter and one receiver. For example, on a duplex channel the transmitter on End A communicates with the receiver on End B and another optic fibre is connected between the transmitter on End B and the receiver on End A.

In parallel optical communication, the devices on either end of the link contain multiple transmitters and receivers, e.g. four transmitters on End A communicate with four receivers on End B. This spreads the data stream over the four optical fibres. This configuration would allow for the operation of a parallel optics transceiver which uses four 2.5 Gb/s transmitters to send one 10 Gb/s signal from A to B. In essence, parallel optical communication is using multiple paths to transmit a signal at a greater data rate than the individual electronics can support. This type of connectivity utilises a ribbon cable type design with all fibres aligned in a straight array, in either a 12 fibre or 24 fibre configuration.

In addition to the cable performance, the choice of physical connection interface is also important. Since parallel-optics technology requires data transmission across multiple fibres simultaneously, a multifibre connector is required. Factory terminated MPO / MTP connectors which have either 12 fibre or 24 fibre array, will support this solution. For example, a 10G system would utilise a single MPO / MTP (12 Fibre) connector between the 2 switches. Modules are placed on the end of the MPO connector to transition from a MPO connector to a 12 Fibre breakout LC duplex or SC duplex cable assembly. This enables connectivity to the switch. 40G and 100G systems require a slightly different configuration.

Difference between MPO and MTP connectors

From the outside there is very little noticeable difference between MPO and MTP connectors. Infact, they are completely compatible and inter-mateable. For example, an MTP trunk cable can plug into an MPO outlet and vice versa.

The main difference is in relation to its optical and mechanical performance. MTP is a registered trademark and design of UsConnec, and provides some advantages over a generic MPO connector. Since MPO / MTP optic fibre alignment is critical to ensure a precise connection there are some benefits in utilising the MTP connector. The MTP connector is a high performance MPO connector with multiple engineered product enhancements to improve optical and mechanical performance when compared to generic MPO connectors.

The MTP optic fibre connector has floating internal ferrule which allows two mated ferrules to maintain contact while under load. In addition, The MTP connector spring design maximizes ribbon clearance for twelve fibre and multifibre ribbon applications to prevent fibre damage.

Overall it provides a more reliable and precise connection.

In addition, it is also important when specifying an MPO/MTP system to ensure the correct polarity options and which cables and outlets have female or male pins.

A specific lengths pre-assembled MTP/MPO Trunk cable with 12 or 24 fibers is delivered to data center for easy installation, because an It is impossible to manually to assemble MPO/MTP plug connector with 12 or 24 fibers on site during installation.MPO-MPO-Patch-cord-10m

The advantages of MPO/MTP Trunk cable with the following advantages

• Higher Quality

Higher quality is usually achieved through factory assembly and inspection of individual parts. A factory-prepared inspection certificate is also useful for longterm documentation and in turn quality assurance purposes.

• Minimum Skew

A crucial factor in achieving a successful parallel optical connection is keeping the signal offset (skew) between the four or ten parallel fibers to an absolute minimum. Only in this way can information be successfully re-synchronized and re-combined at its destination. Factory-assembled trunk cables allow skew to be measured, minimized and logged.

• Shorter Installation Times

Pre-assembled MPO cable systems provide plug-and-play advantages and can be inserted and set up immediately.

This reduces installation time enormously

• Better Protection

Because they are completely assembled at the factory, cables and plug connectors remain completely protected from

environmental influences. Optical fibers that lie open in splice trays are at a minimum exposed to ambient air and may age faster as a result.

• Smaller Cable Volumes

Smaller diameters can be realized in MPO cabling systems that are produced from loose tube cables. The results are

correspondingly smaller cable volumes, better conditions for acclimatization in the data center and a lower fire load.

• Lower Overall Costs

When splice solutions are used, a few factors that are not always foreseeable boost total costs: time-intensive,

equipment-intensive splicing, needs for specialty works, bulk cables, pigtails, splice trays, splicing protection, holders. In contrast, pre-assembled trunk cables not only bring technical advantages, but usually result in lower total costs than splicing solutions.