Keystone Jack Overview

What Is the Keystone Jack?

The keystone jack is a kind of female connector always attached to the end of network patch cable, which is designed for data communications, especially local area networks (LANs). This kind of connector is generally fabricated in a standardized size, hence it can be versatile to work with all brands of patch panels, surface mount boxes and keystone wall plates. As for the structure of keystone jack, you can learn it from the following figure.

Why the Keystone Jack Is Used?

The keystone jack is basically universal in all the brands of patch panels, keystone wall plates, etc. Just taking its installation in the keystone wall plate as an example, various types of keystone jacks can be easily and fast mounted into one wall plate with many ports. Meanwhile, it offers multiple configuration options in data centers and networks utilizing patch panels, as well. The advantage of versatility is one of the most important factor that makes the keystone jack so popular in data communications.

Another important factor is its advantage of diversity. At present, there are many kinds of keystone jacks available in the market, such as, cat5e keystone jack, cat6 keystone jack, cat6a keystone jack, etc. Even special variations of the keystone jack has come into market in recent years to meet the growing requirements of the network. Among these types, the high-density keystone jack has focused on much of the attention that has the ability to maximize the working space where you may feel constrained. As for its application, the high-density keystone jack always works with high-density patch panel, allowing you to fit more individual jacks into a single patch panel. Since the keystone jack has been so diversified, it is an ideal solution for home theater installations or other applications where multiple connections are required.

Furthermore, using the keystone jack can support a clean and professional look for the end connection of the network patch cable, thereby a neat and secure connection can be provided to the home network. Besides, the extra space of the wall plate can greatly save room without leaving an unsightly empty hole, allowing for a safe and secure future expansion at the same time.

How to Punch Down a Keystone Jack?

Correct punching down a keystone jack can greatly ensure the performance and stability of the connection. To help you correctly punch down the keystone jack, here will provide the detailed instructions for punching down a cat5e keystone jack as an example.

• Prepare the required tools for punching down a cat5e keystone jack, including a cable stripper tool, a cable cutter, a cat5e patch cable, a cat5e keystone jack.
• Use the stripper tool to strip the jacket (approximately one inch) in the tip of the cat5e patch cable. You should adjust the stripper in a proper position to score the jacket, avoiding scratching the twisted cables underneath.
• Check and confirm that the four pairs of wires with different colors inside the jacket are in good condition to ensure a successful connection.
• Untwist and straighten all the four pairs of wires and separate them into eight exposed, individual wires.
• Remove the plastic cap from the back of the cat5e keystone jack, and confirm the color order marked beside each termination post of the cat5e keystone jack.
• Put the punch down tool on the outside of the cutting blade, use it to push down each wire of the cat5e patch cable, and lock the wires in their corresponding position by matching the wire color with the color order you find in the cat5e keystone jack.
• After punching down all the eight wires, you should use the cable cutter to cut all the excess wires outside the keystone jack.
• Reattach the plastic cap to the back of the cat5e keystone jack.
• Test and confirm that all the wires have the proper connections.

Conclusion

In short, the keystone jack is very commonly used in data communications due to its versatility and diversity. Meanwhile, it is capable of offering a clean, secure and professional connection and a safe and secure future expansion. Since it has been so popularly used, you are suggested to acquire the skill of punching down the keystone jack that is very easy to grasp and can save a lot of money and time.

Guides for Selecting Ethernet Patch Cable

Ethernet patch cable, the copper-based patch cable, may perform not so good as fiber optic patch cable in deploying Ethernet network, but it is still very commonly used in many applications, such as PCs, routers, and switches, as an accessible, popular and low-cost solution. At present, there are various types of Ethernet patch cables available in the market that may not be very easy to classify if you are not familiar with them. In this paper, it will introduce four widely used types of Ethernet patch cables according to different standards that you can take as reference to select the most suitable one for deploying your network.

STP and UTP Cable

There are two types of Ethernet patch cables according to whether the cable is shielded or not, known as shielded twisted pair (STP) cable and unshielded twisted pair (UTP) cable. As for the structure of these two types of copper cables, here offers their differences in the following figure for your reference. Besides, it is worth mentioning that shielding is one of the common methods to decrease or avoid EMI, aiming at protecting the whole cabling system.

As for the STP cable, it is always made up of even wires that are shielded by a metallic substance. Just taking an eight-strand cable as an example, all the four pairs of the wires are twisted, shielded and then wrapped in another metallic protector, as shown in the above figure. Through shielding, cancellation and wire twisting, the STP cable can be well protected from interference. It is highly recommended to use the STP cable in industrial settings with high amounts of electromagnetic interference (EMI), such as factories with large electronic equipment. However, there is an important issue that should be paid attention to if you choose the STP cable to deploy Ethernet network. After installation, you should check and ensure that it is installed and grounded properly, or the shielded Ethernet cable will act as an antenna and pick up signals when your network runs.

As for the UTP cable, it is easy to learn that it is designed without shielding. Compared to the STP cable, it is much simpler to install and less expensive due to its unshielded property. But without shielding, how to reduce or avoid interference when using the UTP cable? Or this kind of cable has no ability to decrease the interference? In fact, the UTP cable depends on the twisted pair inside the cable to cancel EMI. Meanwhile, it does not require as much maintenance but can transmit data as fast as the STP cable, since it don’t rely on the outer shielding. As for its application, it is always used in domestic and office Ethernet connections, and in any area where there is not a high degree of EMI.

Solid and Stranded Cable

The solid and stranded cable with different features are designed for various applications. Knowing their features and acquiring when and where they should be used will be helpful for you to improve networking performance and efficiency when designing your network. The following will introduce the structure and advantages of these two kinds of copper cables, then you can have a good knowledge of which should be selected and used for deploying your network.

As shown in the above figure, the solid cable consists of a single, solid conducting wire, insulated with non-conductive materials. With the feature of large-diameter wire, it is physically stronger than the stranded cable and capable of remaining stable over a wider range of frequencies, providing superior electrical characteristics and supporting long transmission with high data rates. Meanwhile, it has a lower DC resistance and a lower susceptibility to high frequency effects than the stranded cable due to its large-diameter wire. All these advantages make the solid cable better suited to the new and emerging high-speed Ethernet applications. However, the large diameter feature of solid cable brings a serious disadvantage at the same time. It could be easy to be break for lack of flexibility as they cannot be flexed or bent for many times without breaking. Hence, the solid cable is an ideal solution for horizontal cabling applications with long transmission distance.

Greatly different from the solid cable, the stranded cable is composed of a bundle of twisted, small gauge wire strands. Its diameter of each individual wire strand is much smaller than that of the solid cable, making it much more flexible and hard to break even if it is repeatedly flexed or bent. Although the stranded cable is not so reliable as solid cables for long distance transmission, it features high flexibility that makes itself easy to constantly plugged, unplugged, bent or installed without harm or risk of performance failure, as an optimal choice for short distance transmission.

Conclusion

From this paper, we can learn four widely used types of Ethernet patch cables with different features that are suitable for different applications. The STP cable is always applied in industrial settings with high amounts of EMI, while the UTP cable is more commonly used in domestic and office Ethernet connections, and in any area where there is not a high degree of EMI. If you want to establish a horizontal, long-distance network with high reliability, the solid cable is strongly recommended. But if long distance is unneeded, you are suggested to use the stranded cable which is a good choice for short distance transmission with high flexibility. In short, choosing the most suitable Ethernet patch cable to deploy your network that can greatly improve your network performance and extend life span of your equipment.

Properly Terminate Fiber Optic Cables for a Smooth Connection

In the optical network deployment, fiber optic termination should be an unavoidable and vitally important procedure that enables fiber cross connection and light wave signal distribution. Only when the fiber optic cables in the network are terminated properly can they be protected from dirt or damage so as to achieve a smooth and steady network. Meanwhile, proper fiber optic termination can efficiently avoid the excessive loss of light when the network runs, which strengthens the smooth connection. But how to properly terminate fiber optic cables to ensure a smooth connection? Let’s talk about this topic and find the most suitable method to terminate fiber optic cables for your network.

Proper Methods for Fiber Optic Termination

There are two methods for terminating fiber optic cables, using connectors and splicing, each of which allows for a smooth connection with low light loss and back reflection in a proper manner. We can learn these two methods in the following figure. The method of using connectors to terminate fiber optic cables is shown in the top right corner that is able to mate two fibers for a temporary joint, while the other method is splicing which has the ability to create a permanent joint between the two fibers. As for the step-by-step instructions of these two methods, it will be introduced detailedly in the following text.

Using Connectors to Terminate Fiber Optic Cables

You may often hear about the descriptions like LC to LC patch cord, LC to SC patch cord and LC to FC patch cord when choosing fiber patch cords to deploy your network. Do you understand what do the words “LC” “SC” and ”FC” mean? In fact, they stand for three kinds of connectors that are to terminate the ends of fiber optic cables, with the aim of connecting and disconnecting two fibers for many times without affecting the optical performance of the fiber circuit. To get a smooth fiber circuit, the following will illustrate how to use the connectors to properly terminate fiber optic cables.

• Take out the fiber optic cable that you want to terminate and prepare a fiber cleaver for the termination.
• Strip away the outer jacket, buffer and cladding of the fiber optic cable and cut away the excess aramid yarn.
• Lightly score the fiber by pressing the fiber cleaver. Don’t use the cleaver more than once to score the fiber, so that the fiber will not be broken by unexpected, additional notch.
• Along the score, bend the fiber and the tongue of the cleaver together to break the fiber.
• Use the scale on the cleaver for measuring the bare fiber to ensure that it is long enough, so that it can reach the fiber inside the connector and make the termination work finally.
• Utilize alcohol wipes with at least 90% isopropyl alcohol content and lint-free material to clean the fiber.
• Carefully insert the bare fiber into the connector and crimp the connector onto the buffer.

Notices: Please check and confirm the right types of connectors and their polishing styles before making the termination to avoid non-corresponding installation. Moreover, test periodically during the installation, rather than testing them all after the job is completed to eliminate the possibility of repeating the same errors throughout the installation.

Splicing to Terminate Fiber Optic Cables

When the fiber cable is too long or there are various fiber cables that needs to be mixed, the splicing is strongly recommended to do the fiber optic termination. For instance, splicing a 48-fiber cable and six 8-fiber cables together. Meanwhile, if a buried finer cable is accidentally severed, you are also suggested to use the splicing method to restore the fiber optic cable. The following will introduce the procedures of fusion splicing which may be useful for you to make a proper fiber optic termination.

• Prepare the two fiber ends that need to be spliced together.
• Strip the protective coating, jackets, tubes, strength members, etc, and only leave the bare fiber showing.
• Clean the fiber cables and use score-and-break method to score the fibers, for the sake of proper splicing.
• Properly align the cleaved end-faces of the two fibers, and then utilize an electrical arc to melt them. Hence, the two fiber ends can be permanently welded together.
• Finally use the heat shrink tubing, silicone gel and mechanical crimp protector to protect the splice from outside elements and breakage.

Conclusion

From the mentioned above information, we can easily acquire two proper methods for fiber optic termination, using connectors and splicing, both of which are the useful and effective solutions to achieve smooth connections. Using these two methods to terminate fiber optic cables can protect the fibers from being damaged, avoid the excessive loss of light and keep a stable performance for your network.

In-Depth Study of CWDM Transceivers

It is easy to learn that CWDM stands for Coarse Wavelength Division Multiplexing, which belongs to one of WDM technologies. With the fast development and gradual maturity of WDM technologies, CWDM technology becomes popularly used in recent years that allows for expanding network capacity without more fibers and supporting less expensive and power consuming system. For all these advantages, CWDM technology is applied in many optical equipment. One of the most popular equipment that uses this technology is CWDM optical transceiver, which will be introduced in the following text.

CWDM Transceiver

CWDM transceiver is a kind of optical module typically working with CWDM technology, which is designed for connecting the existing network equipment with CWDM multiplexers/demultiplexers (Mux/Demux). As for its working principle, it is able to combine optical signals with different wavelengths in the multiplexers side and transmit the integrated signal through a single fiber, while splitting the integrated signal into several signals with different wavelengths in the demultiplexers side. And there are eighteen channels available in CWDM transceiver for transmitting signals with different wavelengths from 1270 nm to 1610 nm, such as 1270 nm, 1290 nm, 1310 nm, 1330 nm, etc.

At present, CWDM transceiver can be simply divided into four types, CWDM SFP, CWDM SFP+, CWDM XFP and CWDM X2, both of which will be studied in details. Besides, to better know CWDM transceivers, here offers the figure for the appearance of the four CWDM transceivers for your reference.

CWDM SFP

CWDM SFP is a kind of hot-pluggable optical module, which is SFP MSA (Multi Sourcing Agreement) and IEEE 802.3 & ROHS compliant. Compared to other CWDM transceivers, CWDM SFP is the most commonly used module that connects LC duplex single-mode patch cord to support 1G, 2G and 4G Ethernet network at lengths up to 200 km. In its working process, it enables the network capacity to be increased by transmitting multiple data through a single fiber, with the function of combining optical signals with different wavelength into an integrated signal.

As for the application, CWDM SFP can support the CWDM passive optical system combing CWDM OADM (optical add/drop multiplexer). If you use CWDM SFP to work with transponders and media converters, you will find that the two optical components convert the existing equipment with standard wavelengths or copper ports to CWDM wavelengths in a very convenient way.

CWDM SFP+

CWDM SFP+ is an upgraded version of CWDM SFP that offers a simple way to make 10G network connection. It has the ability to work with up to eight channels for transmitting 10G signals at the wavelengths including 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590nm, and 1610 nm, through single-mode fiber strands. And it can be used in parallel with other SFP+ devices on the same platform.

In contrast to CWDM SFP, it is much more expensive. However, taking 10G Ethernet applications into consideration, CWDM SFP+ is really a cost-effective solution in campus, data center and metropolitan area access networks. After all, it allows for increasing the bandwidth of an existing 10G Ethernet optical infrastructure without adding new fiber strands.

CWDM XFP

Just like CWDM SFP+, CWDM XFP is also used for 10G Ethernet applications with Z-direction design, which complies with CWDM XFP MSA. What’s about the cost? It is also nearly the same as that of CWDM SFP+. Meanwhile, it can transmit 10G signals at the distance up to 100 km, which depends on the wavelengths, fiber types and the CWDM Mux/DeMux insertion loss. Besides, it is mainly used in Storage, IP network and LAN applications, working with the wavelengths from 1270 nm to 1610 nm.

CWDM X2

In comparison with the previous three CWDM transceivers, CWDM X2 is the most expensive one which is suitable for CWDM optical data communications like 10G Ethernet and 10G Fibre Channel applications. Similar to CWDM XFP, it also works with the wavelengths from 1270 nm to 1610 nm, supporting 10G transmission at lengths up to 80 km over SC duplex single-mode fiber cable.

Conclusion

CWDM transceivers can greatly expand the network capacity without additional fibers by connecting the existing network equipment with CWDM multiplexers/demultiplexers (Mux/Demux). It is really a cost effective solution for higher capacity that allows for a highly flexible and available multi-service network. As for the four kinds of CWDM transceivers mentioned above, you can choose the proper one according to their features and your existing network need.

High Density and Capacity Solutions for Your Network

Are you satisfied with your network configuration? Or it no longer meets your requirement for more computing power and higher capacity? Do you consider expanding your system to large facilities, such as, using the advanced switches and fiber enclosures, which may cost a lot? In fact, there are several kinds of high density and cost effective infrastructures successively published and available in the market to address the problems you are encountering, for instance, high density patch cable, high density patch panel, high density fiber enclosure, etc. The detailed information of these three commonly used and high density solutions will be introduced in this post, which may be very useful for you to create more capacity for your network.

High Density Patch Cable

As the demand for higher speed network deployment increases day by day, the cabling density becomes higher and higher, which brings a big challenge to the traditional fiber patch cables. To face this case, high density patch cable, like MPO/MTP fiber patch cable, is designed for rigorous daily use, which is very different from SC fiber patch cable, LC fiber patch cable or other traditional fiber patch cables. This kind of cable features a smaller overall diameter that allows for better cable management by installing in the dense patch cord tray with less space. Except that, it facilitates the airflow to maintain consistent operating temperatures, which is capable of reducing or eliminating the possibility of failure or downtime.

As we all know, if there are many fiber patch cables in the same device or adjacent devices, it could be very difficult to install or manage the patch cables. But the high density patch cable designed with a flexible pull-tab is easily installed or removed, as shown in the following figure. This kind of cable greatly increases the cabling density and maintains connection reliability, which effectively avoids accidentally loosening surrounding connectors for cable management.

High Density Patch Panel

High density patch panel is the device to connect a fiber network feed (via multi-strand or MTP cable) and segment it into standard LC connections in order to interface with 10Gbps devices, which is comprised of a panel enclosure and modular cassettes. From the following figure, we can see an example of the high density patch panel with 12 LC duplex single-mode adapter.

 

As the most convenient solution to solve the limited capacity problem in data centers, it is able to connect different generations of devices like 10Gb, 40Gb, 100Gb devices in a easy, quick and flexible way. Meanwhile, it is very easy to install that don’t need additional tool to finish the connection, greatly reducing the time and labor required of field connector terminations. Besides, the network reconfiguration of high density patch panel is highly adjustable for the modular cassette system. In short, high density patch panel features highly flexibility, adjustability and reliability that offers data centers a very flexible, convenient and cost effective solution.

High Density Fiber Enclosure

High density fiber enclosure is also developed for better cable management and maintenance by making full advantages of the space in data centers. In order to achieve the goal, it is designed with the functions of combining most of the fiber optic connections in the standard modules, giving solid protection for the data center links and greatly increasing the cabling density. The following figure shows an example of high density fiber enclosure for your reference.

At present, fiber enclosures are available in 1U, 2U, 3U, 4U. The 1U rack mount fiber enclosure is the most widely used one, while 4U or larger rack mount fiber enclosures also become popular to meet the ever-increasing need. By using these kinds of high density fiber enclosures, you have easy access to cable connection and management and create more capacity for your network. Meanwhile, it can also save a lot for installation and maintenance.

Conclusion

It can be concluded from this post that there are many kinds of high-density products available in the market that create more capacity for your network, which allow for better cable management, easier maintenance and other advantages. Except these common high-density solutions mentioned above, high speed interconnect optics, cable assemblies, cable management hardware and other high-density products also play important roles in meeting the challenge of higher density and capacity in data centers.

Traceable Fiber Patch Cable Overview

What Is Traceable Fiber Patch Cable?

Traceable fiber patch cable is clearly different from original fiber patch cable that features the exceptionally bright, integrated LED light at each end of the fiber cable, aiming at satisfying the ever-growing demand to quickly and easily identify and trace network connections in today’s high-density and mission-critical infrastructure environments.

As shown in the figure above, the flashing LED light at each end of traceable fiber patch cable is to easily trace individual patch cable from one side to another without pulling or affecting the whole patch cables. By using this kind of fiber patch cable, your network can be fast and simply maintained, while the erroneous connections of network can be also easily found and quickly resolved. In short, traceable fiber patch cable is an ideal solution that allows for easy port identification.

How Does Traceable Fiber Patch Cable Work?

The working process of traceable fiber patch cable is very easy to handle. Just press the activation button on the low-profile plug, the LED lights will flash immediately on both ends of the patch cable for easy identification of where the patch cable is connected. To get a visual understanding of the working process, the following figure shows the detailed information of how to use traceable fiber patch cable for tracing network connection.

Traceable fiber patch cable is capable of eliminating the possibility of accidentally unplugging or connecting wrong patch cable, which is highly recommended in high-density environments. For instance, if there is cable congestion in your network and it is very difficult to find the opposite end of one cable, the traceable fiber patch cable should be very suitable for you to address the problem.

Features and Benefits

Traceable fiber patch cable is designed with distinctive features and benefits, which enables quick and accurate port identification for high-density and high congestion network. It is very different from other fiber patch cables and would be an exceptional alternative to others for its distinctive advantages in the following aspects.

First and foremost, the LED indicators at both ends of the fiber cable offer an visual indication for easy port identification, superior to other fiber patch cables. When the LED tool applies power to the fiber patch cable, it is able to identify the the two ends of the cable, eliminating and avoiding connection mistakes. Secondly, the assemblies are available in single-mode bend insensitive fiber (BIF) and multimode OM3 and OM4 fiber types, both of which have the ability to reduce insertion loss when through high density equipment. Thirdly, all of the assemblies conform with TIA/EIA and IEC intermateability standards, and RoHS compliant. With this design, it greatly saves installation, maintenance and trouble shooting time as a time and cost efficient choice.

Traceable Patch Cables Selection Guides

The types of traceable patch cable are similar to the original fiber patch cable, including single-mode and multimode traceable patch cable, simplex and duplex traceable patch cable and so on. Multimode traceable patch cable is designed for short distance transmission, while single-mode traceable patch cable is more suitable for transmitting signals with much longer distance. If high-speed transmission is required, simplex traceable patch cable must be a good choice. But if the reliability of transmission is quite important, the duplex traceable patch cable is much more recommended.

Conclusion

Traceable fiber patch cable can simplify and accelerate the deployment of high density network with the advantage of easy port identification. At present, there are several types of traceable patch cables that can be chosen for your network according to your network need. Except the common types mentioned above, it is also available in various connectors used for different applications, which is the same as original fiber patch cables like LC SC fiber patch cable and SC ST fiber patch cable. If these types can not meet your needs, you can make custom fiber patch cables which are more suitable for your network to quickly and easily trace connection.

QSFP-40G-UNIV Transceiver—an Ideal Solution for Data Center Upgrade

When choosing 40G transceiver for upgrading your system, you may always find various transceivers that satisfy your needs. For instance, 40G-QSFP-SR4-INT, QFX-QSFP-40G-SR4 are widely applied for 40G short distance transmission and QSFP-40GE-LR4, QSFP-40G-LRL4 for 40G long distance transmission. However, have you ever heard the description for 40G transceiver like QSFP-40G-UNIV? Are you familiar with this 40GBASE module? What’s the difference in contrast to other 40GBASE modules? Why and how it is used? What will data center benefit from it? Let’s talk about the knowledge of QSFP-40G-UNIV and explore the related questions mentioned above.

What’s QSFP-40G-UNIV Transceiver?

QSFP-40G-UNIV transceiver is a pluggable optical transceiver designed with a duplex LC connector and four 10G multiplexed channels to transmit and receive an aggregate 40G signal, achieving 40G data transmission through a single pair of single-mode or multimode fiber. As an ideal solution for data center upgrade, it allows for a very cost-effective migration from 10G to 40G with minimal disruption.

Compared to other 40GBASE modules that are only able to work through one type of the fiber patch cable, QSFP-40G-UNIV transceiver can universally work on both single-mode and multimode fiber patch cable, just like its name “UNIV” implies. For this reason, it is also known as SMF&MMF 40G transceiver or QSFP 40G universal transceiver. As for the transmission distance that QSFP-40G-UNIV transceiver supports, it could be up to 150 meters over OM3/OM4 and 2 kilometers over SMF for 40G data transmission.

Why QSFP-40G-UNIV Transceiver Is Used?

The demand for 40G connections in the data center is growing day by day to accommodate the server consolidation, virtualization, and performance improvements, which brings a big challenge to 40G transceivers. Under this circumstance, QSFP-40G-UNIV transceiver was published and came into market, which makes a great difference in the 40G migration.

As we know, various transceivers are available in the present market for short distance applications, most of which work with MPO-12 connectors and ribbon fiber infrastructures. Hence, if you want to upgrade your system from 10G to 40G, you have to add new fibers for your system or deploy MTP/MPO fiber systems on which you may spend lots of money. To address the problem, QSFP-40G-UNIV transceiver with LC connector has the ability to support several types of cables, which facilitates the migration from 10G to 40G network without redesign or expansion of the existing fiber network. Meanwhile, it is optically interoperable with QSFP-40GE-LR4, QSFP-40G-LRL4 for easy connection to router and switch in existing fiber network, thereby a big convenience can be also provided to achieve 40G long distance applications. What’s more, it offers a transition path between single-mode and multimode modules with lower cost and supports all QSFP+ ports on switches without restrictions.

How Does QSFP-40G-UNIV Transceiver Work?

Are you curious about the working principle of QSFP-40G-UNIV transceiver, which is capable of carrying 40G signals over a duplex fiber cable? After all, the traditional 40G transceiver, like QSFP-40G-SR4, has to work through eight fiber cable. And each cable is used for transmitting or receiving 10G signal to finish the whole 40G link, as shown in the following figure.

From the figure, we can learn that selecting QSFP-40G-SR4 transceiver to achieve 40G connection requires four times more fibers than choosing SFP-10G-SR transceiver to support 10G connection. However, using QSFP-40G-UNIV transceiver allows the 40G connection to be operated over the same duplex fiber infrastructure as SFP-10G-SR transceiver. In its working process, there are four transmitters that convert four 10G electrical signals into four 10G light signals. Then the four 10G light signals are multiplexed as a 40G signal, transmitted through the duplex fiber patch cable, and de-multiplexed into four individual 10G light signals again. Finally, the four light signals will pass through each receiver and be converted into electrical signals.

Conclusion

Compared to traditional 40G transceivers, QSFP-40G-UNIV transceiver is an ideal solution for smooth migration from 10G to 40G without redesign or change of the existing fiber network, which is suitable for both short and long data transmission. Besides, it allows for the transition between multimode and single-mode modules, as a very cost-effective connectivity solution. Hence, if the cabling infrastructure of your network is very complicated, QSFP-40G-UNIV transceiver is highly recommended for you to achieve an easy, fast and smooth migration from 10G to 40G.

40G Active Optical Cable (AOC) Solution

40G active optical cable (AOC) is a cabling technology used for deploying 40G Ethernet network, which uses electrical-to-optical conversion on the cable ends, accepting the same electrical signals as a 40G direct attach cable (DAC). It is terminated with a 40G QSFP+ module on one end, while a 40G QSFP+ module, four 10G SFP+ modules or four duplex LC connectors on the opposite end, as shown in the following figure. To satisfy the increasing needs of higher bandwidth and transmission speed, it was designed for 40G short distance transmission and came into market with a broad prospect under the rapidly developing optical networks.

It is well know that both 40G DAC and 40G QSFP+ module can be also used to achieve 40G short distance interconnection in data center, but 40G AOC seems more widely applied with the same function. Why? In this paper, it will analyze the advantages and disadvantages of 40G AOC in details, giving the answer.

40G AOC Solution vs. 40G DAC Solution

In contrast to 40G DAC solution, 40G AOC solution has a higher performance in the deployment of 40G Ethernet network, especially when the transmission distance of the network is longer than 7 meters. Except the advantage of longer transmission distance, 40G AOC is much thinner, lighter and has a tighter bend radius, all of which make the 40G cabling easier and airflow system more efficient. Undoubtedly, 40G AOC solution is a better choice than 40G DAC solution to deploy 40G Ethernet network.

40G AOC Solution vs. 40G QSFP+ Module Solution

40G QSFP+ module solution for short distance transmission has all the advantages of 40G DAC solution mentioned above to achieve 40G connection in data center. However, 40G DAC is still a better solution that should be highly recommended. Why? The following will analysis the differences between the two solutions, seeking the reason why 40G DAC is more popularly used than 40G QSFP+ module for short distance transmission.

Cost Difference

There is no doubt that 40G AOC has a much lower cost than 40G QSFP+ module because of the following reasons. Firstly, 40G AOC can be directly connected to the system, while 40G QSFP+ module should be connected with extra fiber patch cables. For this reason, 40G AOC, like QSFP to SFP+ breakout cable, is a more cost-effective solution than 40G QSFP+ module. Secondly, there is always the cleanliness issue in the optical connector when 40G QSFP+ module is selected, but 40G AOC can be used without the worry. Thirdly, when troubleshooting the system deployed by 40G AOC, the termination plug don’t need to test, too. All these advantages of 40G AOC allow the 40 migration to be done with less time and money.

Insertion & Return Loss Difference

As we know, when the modules are connected by fiber optic patch cables, it will cause an insertion loss and return loss. However, the issue can be ignored if 40G AOC is selected, because AOC don’t need to connect fiber optic patch cable. Meanwhile, the repeatability and interchangeability of 40G AOC perform better than that of module. As a result, the insertion loss and return loss caused by 40G AOC will be less when the 40 signals is transmitted in the network. Hence, 40G AOC has a higher performance than 40G QSFP+ module for short distance transmission in this aspect.

Transmission Distance Difference

Both QSFP+ module and AOC can support 40G Ethernet network for short distance transmission through OM3 fiber without apparent difference, but the QSFP+ module can control the performance better than AOCs. Hence, it the transmission distance is longer than 300 meters, the QSFP+ module for 40G short transmission distance will be more suitable in order to ensure a good performance.

Conclusion

It can be concluded that AOC is able to support 40G network with longer transmission distance, make the network cabling easier and has a more efficient airflow system than 40G DAC. It can also be found that AOC takes less money and time to make the 40G migration with less insertion loss and return loss than QSFP+ module for short distance transmission. What should be paid attention to is that QSFP+ module will be a better solution when the transmission distance is longer than 300 meters.

Is PSM or CWDM More Cost-effective for 40GBASE-LR4 QSFP+ Optic?

Since 40G Ethernet network becomes much more widely used than ever before to meet the data center needs, there are various 40G optics available in today’s fiber market for different applications. As for short distance application, 40GBASE-SR4 QSFP+ optic has a high performance with the parallel multimode fiber (MMF) link. While for long distance application, 40GBASE-LR4 QSFP+ optic has been put into use that can work with two kinds of links, parallel single-mode fiber (PSM) link and coarse wavelength division multiplexing (CWDM) link. Do you have a good knowledge about the two links? Which one is more cost-effective in 40G long distance transmission? In this paper, it will mainly talk about this topic that may guide you to choose the right link for 40GBASE-LR4 QSFP+ optic.

40GBASE-LR4 QSFP+ Optic with PSM Link

How does the 40GBASE-LR4 QSFP+ optic work with PSM Link? Generally, it is designed to transmit signals through parallel single-mode fiber (SMF) link that can be also called PSM QSFP+ optic. A PSM QSFP+ optic has four independent channels to transmit and receive 10G signal to achieve a total 40G signal transmission at lengths up to 10 km. MTP/MPO fiber ribbon connector is required in this optic to match with the parallel single-mode fiber link, while the guide pins inside the receptacle is also needed to ensure proper alignment. What should be paid attention to is that the single-mode fiber cable cannot be twisted for the sake of channel to channel alignment.

In its working process, the transmitter module of the optic will accept electrical input signals, while the receiver module has the ability to convert parallel optical input signals via a photo detector array into parallel electrical output signals. Both electrical input and output signals are voltage compatible with common mode logic (CML) levels, supporting a data rates up to 10.3G per channel.

40GBASE-LR4 QSFP+ Optic with CWDM Link

The 40GBASE-LR4 QSFP+ optic with CWDM link is also known as CWDM QSFP+ optic, which takes full advantages of CWDM technology to achieve 40G transmission. Similar to the PSM QSFP+ optic, it also offers four transmitting and receiving channels, and each of the channel is capable of 10G operation for a total 40G data rate with a reach of up to 10 km through single-mode fiber cable.

However, the working process of CWDM QSFP+ optic is much complicated than the previous one, since the duplex LC connector is implemented to accommodate CWDM technology in this optic as shown in the following figure. In its working process, it will firstly use a driven 4-wavelength distributed feedback (DFB) laser array to convert four 10G electrical inputs signals to four CWDM optical signals with different wavelengths, generally 1271, 1291, 1311 and 1331 nm, and then multiplexes these CWDM signals into a single channel as a 40G signal, propagating out of the transmitter module through the SMF. When these CWDM signals come to the receiver module, they will be de-multiplexed into four individual 10G optical signals and transmitted through each individual channel, which will finally be collected by a discrete photo diode, amplified by a transimpedance amplifier (TIA) and output as electric signals.

Which One Is More Cost-effective?

As we know, 40GBASE-LR4 QSFP+ optic can work with either CWDM link or PSM link, supporting 40G Ethernet network at lengths up to 10 km. Then, which one is more cost-effective? If we only consider the QSFP+ optic cost, it is apparent that the PSM QSFP+ optic is more cost-effective with a single uncooled CW laser and relatively simple array-fiber coupling to an MTP connector.

However, since these two optics are used for long distance transmission, the infrastructure cost for the whole link should be taken into consideration. As mentioned above, the PSM QSFP+ optic uses eight optical single-mode fibers for transmission, but the CWDM one only needs 2 optical single-mode fibers. When the link distance is very long, the fiber cost in PSM QSFP+ optic solution would be much more expensive. Except that, the entire optical fiber infrastructure within a data center has to be changed to accommodate MTP connectors and ribbon cables if the PSM QSFP+ optic is selected to deploy for 40G Ethernet network.

In conclusion, deploying 40G Ethernet network with CWDM QSFP+ optic is a good choice for long distance transmission, which needs much less fibers and enables data center operators to upgrade to 40G connectivity without making any changes.