Selecting Proper Fiber Jumpers for 40G QSFP+ Modules

Many servers in data center can support 40G Ethernet transmissions now. 40Gb QSFP+ is considered to be an economical solution for 40G transmission in data center. And to make them run normally and effectively, fiber patch cables must be used to connect those QSFP+ transceivers plugged in Ethernet switches, as shown in the following picture. As the structure of a 40G transmission is more complex, the selection of fiber patch cords for 40G QSFP+ optics becomes more difficult. This article focuses on how to select proper fiber jumpers for 40G QSFP+ transceivers.

Before jumping to a conclusion, numerous things need to be taken into consideration when selecting a fiber patch cable for a 40G QSFP+ transceiver in practical cabling. In this article, three factors are introduced: the cable type of fiber patch cords, the connector type of fiber patch cords, and ports of switches that need to be connected.

Cable Type

The first factor to consider is the cable type. Optical signals with the same wavelength perform differently when they run through different types of cables. For example, can a 40GBASE QSFP+ transceiver working on wavelength of 850nm be used with OM1 fiber patch cords? Usually, signals with wavelength of 850nm are transmitted over short distance. Thus selecting a multimode fiber patch cord will be more economical. OM1 fiber patch cables are ususally suggested for 100Mb/s and 1000Mb/s networks, and cannot support 40G transmission, because the transmission distance reduces as the data rate raises. OM3 fiber patch cables and OM4 fiber patch cables, these two types of optimized multimode fiber optic cables, are recommended for your 40G transmissions over short distance. And for long distance transmission, you can choose single-mode fiber patch cables.

Connector Type

The second factor to consider is what types of connectors are attached on both ends of fiber patch cords. Connector types are usually decided by the interfaces of 40G optical transceivers. Usually, 40G QSFP+ transceivers for short distance are armed with MPO interfaces, and for long distance transmission usually employ LC interfaces. For example, Avago AFBR-79E3PZ compatible 40GBASE-SR4 QSFP+ transceiver has MTP/MPO interface, and can support up to 400m over OM4 MMF. However, there are also exceptions. 40G QSFP+ transceivers like 40GBASE-PLR4 QSFP+ transceiver and 40GBASE-PLRL4 QSFP+ transceiver, they are with MPO interfaces but they can support transmission over long distance. One characteristic of MPO connector is high density which can perfectly satisfy the requirements of 40G transmission. But this kind of connection makes the polarity complex. So when selecting this kind of fiber patch cord, it is very necessary to take the polarity into consideration. The picture below shows 40G QSFP+ transceivers with MPO interfaces and LC interfaces.

Switch Ports

The third factor is ports of switches that need to be connected. During practical cabling, two situations are common. One is 40G QSFP+ to 40G QSFP+ cabling and the other is 40G QSFP+ to 10G SFP+ cabling. For 40G QSFP+ to 40G QSFP+ cabling: 40GBASE-SR4 QSFP+ transceiver can be used with OM3 fiber patch cable with MPO interfaces to support up to 100m, and with OM4 fiber patch cable with MPO interfaces to support up to 150m; 40GBASE-LR4 QSFP+ transceiver can be used with single-mode fiber patch cables with LC connectors to support up to 10km. For 40G QSFP+ to 10G SFP+ cabling, fan out patch cable with MPO connectors on one end and four LC duplex connectors on the other end is suggested.

Conclusion

When choosing a fiber patch cord for a 40G QSFP+ transceiver, you need to consider these three factors, the cable type, the connector type and the switch ports. You have to figure out first whether you need single-mode fiber patch cords or multi-mode fiber patch cords, MPO connectors or LC connectors, or QSFP+ to QSFP+ cabling or QSFP+ to 4SFP+ cabling. Fiberstore can provide you with professional one-stop service including the cost-effective and reliable network designing and 40G products.

100G Optical Transceivers Overview

To meet the increasing demands for higher speeds and greater scalability, many service providers and enterprise data centers are undergoing an infrastructure transformation to get higher levels of performance and reliability. Optical transceiver is an integral part of overall system design to achieve high performance. 40G and 100G fiber optic transceivers, such as Cisco CFP-40G-LR4 CFP transceiver, and Dell CFP-100G-LR4 CFP transceiver, have become preferable choices for more and more data centers as 1G and 10G cannot meet the their needs of bandwidth-hungry applications. Adopting 100G transceivers not only accelerates data flow throughout your data center or enterprise, but also provides CAPEX (capital expenditures), OPEX (operating expenditures) and time savings. This article talks about options of 100G transceiver modules for your applications.

100G CFP/CFP2/CFP4 Transceiver

When the IEEE finished the first 100G standard for Ethernet networks, the transceiver industry launched an alphabet soup of form factors. The CFP transceiver emerged first. "C" stands for 100, and FP for "form-factor pluggable". CFP transceiver is specified by multi-source agreement (MSA) between competing manufacturers. CFP transceiver was designed after SFP interface, but it is significantly larger to support 100 Gbit/s data rates. While the electrical connection of a CFP transceiver uses 10 x 10 Gbit/s lanes in each direction (RX, TX), the optical connection can support both 10 x 10 Gbit/s and 4 x 25 Gbit/s variants of 100 Gbit/s interconnects.

With improvements in technology, CFP2 and CFP4 specifications have appeared to allow higher performance and higher density. Having similar electrical connection with a CFP transceiver, CFP2 transceiver and CFP4 transceiver specify a form-factor of 1/2 and 1/4 respectively in size of a CFP transceiver. These three modules are not interchangeable, but would be inter-operable at the optical interface with appropriate connectors.

100G QSFP28 Transceiver

100G QSFP28 transceiver is the exact same footprint as the 40G QSFP+ transceiver. The "Q" is for "quad". Just as a 40G QSFP+ transceiver is implemented using four 10 Gbit/s lanes, 100G QSFP28 transceiver is implemented with four 25 Gbit/s lanes. With an upgraded electrical interface to support signaling rates up to 28 Gbit/s, 100G QSFP28 transceiver makes it as easy to deploy 100G networks as 10G networks. Compared to other transceiver alternatives, 100G QSFP28 transceiver increases density and decreases power and price per bit. It has become the universal data center form factor.

QSFP28 transceiver has several advantages. QSFP28 transceiver increases front-panel density by 250% over QSFP+ transceiver. The form factor and the maximum number of ports are the same, but the lane speeds are increased from 10 Gbit/s to 25 Gbit/s. The increase in panel density is even more dramatic when compared to some other 100 Gbit/s form factor: 450% versus the CFP2. QSFP28 transceivers can be based on either VCSELs (for shorter distances on multimode fiber) or silicon photonics (for longer distances on single-mode fiber). The advent of silicon photonics enables QSFP28 transceivers to support any data center to reach up to 2 km or more. Silicon photonics provides a high degree of integration. The picture below shows a 100G QSFP28 SR4 transceiver.

100G Transceiver Solutions from Fiberstore

Fiberstore is a professional manufacturer and supplier in optical communication industry. We provide a complete range of 100G optical transceivers for your data center applications. We have sufficient supply of CFP and CFP2 modules, which can be shipped immediately after ordering. For 100G QSFP28 transceivers, we have 100GBASE-SR4 QSFP28 transceivers and 100GBASE-LR4 QSFP28 transceivers. With our serious cost control, the prices of all our 100G fiber optic transceivers are much more affordable than the similar products in the market and they can be compatible with many major brands. For more details, please visit www.fs.com or contact over sales@fs.com.

Testing and Verification of 3rd-party Optical Transceivers

3rd-party fiber optic transceivers has now been perferable and widely used as optical transmission solutions. High quality and high performance compatible 3rd-party optical transceivers can meet your needs for your applications, such as Intel E10GSFPSR compatible 1000BASE-SX and 10GBASE-SR SFP+ transceiver, or Finisar Intel FTLX8571D3BCV-IT compatible 10GBASE-SR and 1000BASE-SX SFP+ transceiver, which are with high performance and can save you money at the same time. To ensure the compatibility of 3rd-party optical transceivers, they need to be carefully and thoroughly tested and verified. This post will talk about several testing and verification methods of 3rd-party optical transceivers.

Popularity of 3rd-Party Optical Transceivers

Nowadays, more and more companies or users prefer to choose 3rd-party optical transceivers. The increasing market demands for 3rd-party optical transceivers illustrate this point. An officially-branded transceiver and a 3rd-party plug has actually no big difference. As long as optical transceivers meet the same international standards, there is no question of compatibility between fiber optic transceiver modules. Most "third party" optical transceivers are made and assembled in exactly the same plants assembling officially-branded transceivers. The primary benefit of using third party optical transceivers is the cost savings. The difference in price often exceeds 80 percent or more. Cost of optical transceivers is a significant part of the total system expenditure. It is important for designers to minimize the cost. Significant savings brought by third party optical transceivers can enable designers to re-invest and make their designs better. This is why 3rd-party optical transceivers have been increasingly popular with users. The following picture shows an HP JD089B compatible 1000BASE-T SFP copper transceiver. It is fully compatible with HP devices.

Methods of Testing and Verification

Before inserting a 3rd-party optical transceiver module into your network, it is very necessary to test and verify that the 3rd-party optical transceiver module can function well and will not do any damage to your network. There are several methods to test and verify 3rd-party optical transceiver modules, but it is not always as easy as it seems. Here is what you need to know if you are considering testing and verifying 3rd-party optical transceiver modules.

1. Test Bit-Error Ratio: You must always operate within an acceptable bit-error ratio (BER) in a digital communication system. Whether you are testing an interface bus in a laptop computer or a telecommunications link, you have to follow this rule. Generally, in a digital communication system, it should be no more than one error in 1012 bits. If the desired BER is not reached, you should check the transmitter, or the receiver, or both.

2. Test Minimal Power Level and Jitter Level: A receiver needs to achieve a minimum power level to achieve the BER target. The level achieved will dictate the minimum allowed output power. Likewise, if the receiver can only achieve a certain level of jitter, this will be used to define the maximum amount of jitter that can be received from the transmitter without malfunctioning. Transmitter parameters may specify the wavelength and the output waveform shape.

3. Test Interoperability with a Worst-Case Transmitter: Network specifications should determine whether a worst-case transmitter will interoperate with a receiver. Transmitters should also have a signal sufficient enough to support the worst-case transceiver.

4. Verify Compliance with Multiple Samples: Several waveform samples are required to remain compliant. Sometimes, a larger population of waveform samples will provide an accurate assessment of transmitter performance. The oscilloscope will collect more data, but more samples will contribute to the increase of likelihood of mask violations. The results are either pass or fail, so it is important to acquire as many samples as possible to get an accurate assessment, which requires aligning the mask to the waveform.

5. Understand Instrumentation Effects: Keep in mind that any transceiver test can be skewed due to the oscilloscope's frequency response. You can achieve consistent results with a reference receiver. Most tests will use a fourth-order Bessel filter response, and the 3-dB bandwidth is at 75 percent of the data rate.

6. Consider Expanding Your Eye Mask: When you expand the eye mask, you can verify a compliant hit ratio. Only a small number of samples are capable of intersecting a mask. Most oscilloscopes will include a modified version of the classic eye-mask test. Once you have the desired number of samples, you can determine how far you can expand the mask. Each test will determine how far you can expand the mask before the mask hits to the total waveform exceeds the ratio.

Conclusion

Several methods to test and verify third-party optical transceiver modules are introduced above. Hope that they can help you avoid pitfalls, and assist you to test and verify your 3rd-party optical transceivers with ease. It is a necessary step to test and verify third-party optical transceiver modules before using them in a network.

QSFP+ DACs and AOCs for 40G Migration

Gradually, 1G and 10G data rates are becoming not adequate enough to meet the ever-growing needs of high-bandwidth applications. Now 40G Ethernet has been the trend. 40G Ethernet is actually a transitional phase. There are practical reasons for its popularity. Products for 40G Ethernet such as 40G QSFP+ transceivers, 40G QSFP+ direct attach copper (DAC) cables and active optical cables (AOCs) are very popular in the market. 40G QSFP+ DACs and QSFP+ AOCs are cost-effective alternative solutions in short reach interconnections. In this post, a detailed introduction to 40G QSFP+ DACs and QSFP+ AOCs will be given.

What Are QSFP+ DACs and QSFP+ AOCs?

40G QSFP+ DACs and QSFP+ AOCs are two kinds of optical transceiver assemblies, which are terminated with transceiver-style plugs to be used in the same ports where optical transceivers are used. QSFP+ AOCs, such as Cisco QSFP-H40G-AOC1M compatible 40G QSFP+ AOC, are active devices, which incorporate active electrical and optical components to boost/receive signal via optical fiber. QSFP+ DACs can be both passive and active. Passive DACs (often called PCCs), such as Cisco QSFP-4SFP10G-CU3M compatible 40G QSFP+ to 4x10G SFP+ passive DAC, have no active circuitry, which means there is a direct connection between copper cable and QSFP+ transceiver's printed circuit board (PCB) electrical contacts. Active DACs (often called ACCs) incorporate active component to boost/receive signal via copper cable. The following picture shows the general internal structure of AOCs and DACs.

QSFP+ DACs VS QSFP+ AOCs

QSFP+ DACs and QSFP+ AOCs are ideal solutions for short-distance interconnection, and they are widely used in data centers. This part will talk about advantages and disadvantages of QSFP+ DACs and QSFP+ AOCs respectively.

QSFP+ DACs

Nowadays people may think that copper technology is out of fashion compared to fiber technology. It is not true for QSFP+ DAC cables. QSFP+ DACs still get their roles in the market for the following advantages.

• Interchangeability—QSFP+ DACs are interchangeable and hot swappable with fiber optic modules.
• Enough data rate for various applications—QSFP+ DAC cables can support higher data rates than traditional copper interfaces. QSFP+ DAC cables offer a cost-effective way to establish a 40G link between QSFP+ ports of QSFP+ switches within racks and across adjacent racks.
• Low cost—Copper cables are much cheaper than fiber cables, which makes QSFP+ DACs a cost-effective solution for short reach applications.

The defect of QSFP+ DACs is that they are heavy and bulky, making them difficult to be managed. Furthermore, due to the nature of electrical signals, DAC cables are vulnerable to the effects of electromagnetic interference (EMI), such as undesirable responses, degradation, or complete system failure.

QSFP+ AOCs

Offering reliable transport for aggregated data rates up to 40 Gbps, QSFP+ AOCs provide customers with flexibility of traditional optical modules by interfacing to systems via a standard QSFP MSA connector. QSFP+ AOCs are premium products, offering several benefits, as shown below.

• Great bandwidth—QSFP+ AOCs have a throughput of up to 40 Gbps with QSFP+ transceivers. They are ideal for the high density signal transmission in most data centers and high performance computing applications.
• EMI immunity—Optical fiber is a kind of dielectric (not able to conduct electric current), QSFP+ AOCs are immune to electromagnetic energy.
• Light weight—Fiber cables are lighter than copper cables. QSFP+ AOC weighs less than a comparable DAC cable.

Compared with QSFP+ DAC cables, the drawback of QSFP+ AOCs is that they may be a little more expensive for customers.

Conclusion

QSFP+ DACs and QSFP+ AOCs use the same port as an optical transceiver but with significant cost and power savings in short reach applications. This is very important in the 40G migration for the reason that QSFP+ DACs and QSFP+ AOCs can fill the need for short, cost-effective connectivity and provide a power-efficient and cost-effective replacement to 40G optical transceivers.

Which One to Choose, Singlemode QSFP+ or Multimode QSFP+?

Fiber optic transceivers also have singlemode and multimode types according to the fiber they work with. A simglemode QSFP+ transceiver works with singlemode fiber, and a multimode QSFP+ transceiver works with multimode fiber. What are thwy and what is the difference between them? How to choose? A cpmparison between these two kinds of QSFP+ transceivers will be given in this post.

Singlemode QSFP+ vs. Multimode QSFP+

Singlemode QSFP+: Singlemode fiber (SMF) has a tighter tolerance. The core of a singlemode fiber is smaller and the laser wavelength is narrower, which means that SMF has the capability for higher bandwidth and much longer transmission distances. Singlemode QSFP+ (SMF QSFP+) transceiver works mainly in 1310nm wavelength. It is mainly used for long distance transmission. There are several different types of singlemode QSFP+ transceivers. And different types can achieve different transmission distances, such as 500m, 1km, 2km, 10km or even 40km. For example, Cisco QSFP-40G-LR4 compatible 40GBASE-LR4 QSFP+ transceiver, as shown below, is a singlemode QSFP+ transceiver, uses duplex LC connector, and can transmit up to 10km. SMF QSFP+ transceivers usually use duplex LC connectors, and some types can use MPO/MTP connectors.

Multimode QSFP+: Multimode fiber (MMF) has a much bigger core and usually uses a longer wavelength of light. Optics used in MMF have a higher capability to gather light from the laser. In practical terms, this means that the optics can be cheaper. Common multimode QSFP+ (MMF QSFP+) transceiver works in 850nm wavelength and is mainly used for short distance transmission reaching 100m and 500m. For instance, Cisco QSFP-40G-SR4-S compatible 40GBASE-SR4 QSFP+ transceiver, as shown below, is a multimode QSFP+ transceiver, uses MTP/MPO connector, and can transmit up to 150m over OM4 MMF. Multimode QSFP+ transceiver is not able to transmit over long distance, but it can transport many kinds of optical signals. MMF QSFP+ transceivers usually use MPO/MTP connectors, but some SMF&MMF QSFP+ transceivers can also use duplex LC connectors.

Which One to Choose, Singlemode or Multimode?

SMF QSFP+ transceiver and MMF QSFP+ transceiver have different transmission distances and interface connectors, which are the two important factors you should consider when making make a decision. SMF QSFP+ transceivers are for long transmission distances and MMF QSFP+ transceivers are mainly for short transmission distances.

Notes for Using Singlemode QSFP+ and Multimode QSFP+

• Ensure that the QSFP+ transceivers in both ends of the fiber patch cord are of the same wavelength. A simple method is that the color of the modules must be consistent.
• Ensure the data accuracy. Short-wave QSFP+ modules use with multimode fibers (ie. aqua OM3 or OM4 fiber patch cord), while long-wave QSFP+ modules use with single-mode fiber (ie. yellow fiber patch cord).
• Do not over bend or wind fiber optic cables when using them, which will increase the attenuation of light in transmission.
• Use the dust plug to protect the optical bore when the QSFP+ transceiver is not in use.

Conclusion

When choosing a QSFP+ transceiver, first you need to figure out the transmission distance and wavelength you need. It is very crucial and can help you choose the right QSFP+ module. Besides, the cost of transceiver modules is also a very important factor for your consideration. An alternative is you can choose compatible modules without sacrificing quality and reliability. Fiberstore provides all kind of 100% compatible QSFP+ modules branded by many famous companies, such as Cisco, HP, Juniper, Brocade, and Finisar, etc.

MTP/MPO Cables — A Good Solution for Your High Density Applications

With rapidly growing bandwidth demands, data centers have to achieve ultra-high density in cabling to accommodate all connections. MTP/MPOtechnology with multi-fiber connectors offers an ideal solution for high-performance data networks in data centers. There are several MTP/MPO cable solutions, such as MTP/MPO trunk cables, MTP/MPO harness cables and MTP/MPO cassettes. And all these three kinds of MTP/MPO solutions have their own special applications and advantages. This article will give a brief introduction to them.

MTP/MPO Trunk Cable

An MTP/MPO trunk cable is terminated on both ends with MTP/MPO connectors (as shown in the following picture). MTP/MPO trunk cables are available with 12, 24, 48 or 72 fibers. These high count MTP/MPO assemblies are ideal for backbone and data center applications that require a high fiber count in a limited space. The plug and play solutions use micro core cable to maximize bend radius and minimize cable weight and size. MTP/MPO trunk cables have several advantages:

• High quality—MTP/MPO trunk cables are factory pre-terminated, tested and packaged along with the test reports. These reports serve as long-term documentation and quality control.
• Decreasing cable volume—MTP/MPO trunk cables have very small diameters, which decrease the cable volume and improve the air-conditioning conditions in data centers.
• Time saving—With the special plug and play design, MTP/MPO trunk cables can be incorporated and immediately plugged in. It greatly helps reduce the installation time. You don’t need to terminate them in the field, which can be a time- and energy-consuming project.

MTP/MPO Harness Cable

MTP/MPO harness cable (as shown in the following picture) is also called MTP/MPO fan-out cable or MTP/MPO breakout cable. MTP/MPO harness cable has a single MTP connector on one end and on the other end it breaks out into 6 or 12 connectors (LC, SC, ST, etc.). An MTP/MPO breakout cable is available in 4, 6, 8, or 12 fiber ribbon configurations with various length options like 10, 20, or 30 meters and other customized lengths. MTP/MPO fan-out assemblies provide connection to equipment or panels that are terminated with ST, SC, FDDI, or ESCON connectors and meet a variety of fiber cabling requirements. Such assemblies are pre-wired available for patch panels and wall enclosures. They are designed for high density applications with required high performance. Benefits of MTP/MPO harness cable include:

• Space saving—The active equipment and backbone cable is good for saving space.
• Easy deployment—Factory terminated system saves installation and network reconfiguration time.
• Reliability—High standard components are used in the manufacturing process to guarantee the product quality.

MTP/MPO Cassette

MTP/MPO cassettes are designed to reduce installation time and cost for an optical network infrastructure in the premises environment. MTP/MPO cassette modules provide secure transition between MTP/MPO and LC or SC discrete connectors. They are used to interconnect MTP/MPO backbones with LC or SC patching. The modular system allows for rapid deployment of high density data center infrastructure as well as improved troubleshooting and reconfiguration during moves, adds and changes. Advantages of MTP/MPO cassettes are:

• Optimized performance—Low insertion losses and power penalties in tight power budget, high-speed network environments.
• High density—12 or 24 fiber cassettes can be mounted in 1U scaling up to 72 or in 3U scaling up to 336 discrete LC connectors.
• MTP/MPO interface—MTP/MPO components feature superior optical and mechanical properties.

Applications of MTP/MPO Cable

MTP/MPO cables are a good choice for a wide variety of applications. They can be used for backbones, disaster recovery, building fiber optic distribution, quick setup of new wiring hubs, warehouses, direct termination of ribbon cables, repair of plug and play universal system solutions, and parallel optical interconnects between servers.

MTP/MPO system is a good solution for data center applications. They can enable thousands of connections. Fiberstore offers a wide range of fiber optic patch cables, including all kinds of MTP/MPO cables, like MTP/MPO trunk cables, MTP/MPO harness cables and MTP/MPO cassettes. All those MTP/MPO cables are pre-terminated and tested to make sure high performance.

SFP+ Direct Attach Cable Overview

More bandwidth is needed to support the use of server virtualization. The amount and type of devices residing on the network has also dramatically increased the amount of data that needs to be transmitted to and from storage area networks (SANs). SFP+ direct attach cable (DAC), which provides a lower-power means for operation on short fiber optic links or short copper connections, has been a preferable solution to accommodate the ever-growing number of operating systems and applications and the significantly increased data transmission between the servers and switches. This post will give a brief introduction to SFP+ direct attach cable.

What Is SFP+ Direct Attach Cable?

First, we need to know what SFP+ direct attach cable is. It is a fixed assembly that is purchased at a given length, with SFP+ connector modules permanently attached to each end of the cable. SFP+ direct attach cable uses an enhanced SFP+ connector to transmit and receive 10Gbps data through one paired transmitters and receivers over a thin twinax cable or a fiber optic cable. It provides high performance in 10 Gigabit Ethernet network applications. 10G SFP+ direct attach cable is designed to use the same port as an optical transceiver, but compared with optical transceivers, the connector modules attached to the cable leave out the expensive optical lasers and other electronic components, thus achieving significant cost savings and power savings in short reach applications.

Advantages of SFP+ Direct Attach Cable

SFP+ direct attach cable is a low cost, low power consumption and low latency solution that is ideal for high-density, in-rack 10Gbps connections between servers and switches. It provides better cable management for high-density deployments and enhanced electrical characteristics for the most reliable signal transmission. Here are several outstanding advantages of SFP+ direct attach cables.

• MSA compliant—fully conform to the SFP+ MSA specifications
• High speed—support 10 Gbps data rates with backwards compatibility to 1 Gbps
• Reliability—RoHS compliant with excellent EMI performance and high reliability
• Scalability and flexibility—provide enhanced scalability and flexibility, and higher density for today's data centers and storage area networks
• Space saving—offer the smallest 10 gigabit form factor and a small overall cable diameter for higher density and optimized rack space in 10G Ethernet uplinks and Fibre Channel
• Cost saving—cost up to three times less than fiber optic solutions, while offering lower latency and consuming up to 50% less power per port than current copper twisted-pair cabling systems

Types of SFP+ Direct Attach Cable

Generally speaking, SFP+ direct attach cable can be divided into SFP+ direct attach copper cables and SFP+ active optical cables (AOCs). This part will discuss these two kinds of SFP+ direct attach cables.

There are two types of SFP+ direct attach copper cables, SFP+ active copper cable (ACC) and SFP+ passive copper cable (PCC). SFP+ passive copper cable (PCC), or passive SFP+ DAC, is fully compliant to the SFF-8431 SFP+ MSA. It has no signal amplification in the cable assembly. When it is utilized, electronic dispersion compensation (EDC) is typically used on the host board designs. EDC allows for an extended length of passive cable assemblies. They deliver high-speed connectivity between active equipment with SFP+ ports. The copper cable trunks are made to order, reducing installation time and maximizing flexibility. The low power consumption assists in making the passive copper cable assembly an economic solution for within rack or rack to rack applications. SFP+ active copper cable (ACC) has signal amplification and equalization in the cable assembly. SFP+ ACC assemblies are typically used in host systems that do not employ EDC. They also incorporate Rx LOS and Tx Disable features. As with passive cables, the industry standard EEPROM signature enables the host system to differentiate between an active copper cable and a fiber optic transceiver. The picture below shows an HP JG081C compatible 10G SFP+ passive direct attach copper cable.

SFP+ active optical cable is composed of SFP+ optical transceivers in both ends and fiber optic cable in between. This integrated optical module solution removes the complicated optical fiber interface and brings friendly electrical-to-electrical interface to users. SFP+ AOC accepts the same electrical inputs as a traditional copper cable. It uses optical fiber and electrical-optical conversion on the cable ends to improve speed and data transmission distance of the cable while not sacrificing compatibility with standard electrical interfaces. SFP+ AOC is designed to meet the requirements of high speed, high density and low power consumption for applications in today’s data centers via optical fiber wire. It has been a preferable interconnect solution for SFP+ applications. SFP+ AOC is compliant to industrial standard SFP MSA and provides high performance SFP+ interfaces, supporting 10Gb/s bi-directional operation. The image below shows a Cisco SFP-10G-AOC10M compatible 10G SFP+ active optical cable.

Conclusion

SFP+ direct attach cable provides a cost-effective and low power consumption solution for high-density 10 Gigabit connections. These three types of 10G SFP+ direct attach cable assemblies, 10G SFP+ passive copper cable (PCC), 10G SFP+ active copper cable (ACC), and 10G SFP+ active optical cable (AOC) are of their special applications. SFP+ direct attach cable has a lot of advantages. It now has been a very popular choice in the market.