Three Cabling Solutions for 40G Network

Network technology has been developed rapidly and many data centers are utilizing 40G network to satisfy their needs for high density cabling and high speed data transmission. When it comes to 40G network cabling solutions, MPO fiber optic cable assemblies are most used by data center managers. This article is going to introduce three cabling solutions for 40G network—cabling with no conversion component, cabling with conversion module and cabling with conversion harness.

Cabling With No Conversion Component

For cabling with no conversion component solution, in fact, it is a Base-12 MTP connectivity solution. The 12-fiber MTP trunk cables are deployed in the whole 40G connectivity. But in this cabling solution, four fibers are not used. Apart from this, there will be additional cost associated with the purchase of additional fibers. Though this solution does notuse 33% of the installed fiber and may require more cable raceway congestion, it does have the advantage of simplicity and lowest link attenuation.

Cabling With Conversion Module

With the use of conversion module MPO patch panel, the unused fibers can be converted into usable fiber links. For every two 12-fiber MTP connectors in the backbone cable, we can create three 8-fiber links. Using Base-12 connectivity and Base-8 connectivity together realizes 100% fiber utilization. When reusing existing deployed MTP cabling, great value will be gained if using conversion module to use all previously deployed fibers, and we can eliminate the cost of having to deploy additional cabling.

Cabling With Conversion Harness

The cabling with conversion harness solution uses standard MPO patch panel and 2×3 MPO conversion harness. It can achieve full fiber utilization. Although it seems attractive, it involves considerable cabling challenges. For instance, if you only need two 40G connections to the equipment, what do you do with the third 8-fiber MTP connection? Or what if the 40G ports are in different chassis blades or completely different chassis switches? The result will be long assemblies, which will be difficult to manage in an organized way. For this reason, this kind of solution is expected to be the least desirable and so the least deployed method.

Which One to Choose?

If you are installing new cabling, then you can consider cabling with no conversion component solution, assuming that the cable raceway is not a concern. If you are using previously installed MTP trunks, cabling with conversion module solution is recommended which can realize 100% fiber utilization while maintaining any port to any port patching. The cabling with conversion harness solution is typically deployed only in specific applications, such as at the ToR switch, where 40G ports are in a close cluster and patching between blades in a chassis switch is not required.


It is not difficult to find that each type of cabling solution has their own advantages and disadvantages. As for which on to choose, it all depends on your specific network deployment environment and requirements. After reading the content above, I hope you can have a better understanding of these three cabling solutions for 40G network and choose a suitable cabling solution for your network deployment.

Things Should Be Noticed Before Choosing 24-Fiber MPO Cable

In the process of migrating to greater bandwidth 40G and 100G network, MTP cabling system which provides high density and high performance plays an important role. Whether to use 12-fiber or 24-fiber MPO cable has been a hot topic in higher speed networking migration. In my previous blog Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration, we have indicated that MPO 24 fiber cable is more suitable for 40G and 100G network. Besides, with active equipment planning to use a single 24-fiber MPO interface for 100G and the channel currently requiring 20 fibers, many IT managers are also considering the use of 24-fiber MPO solutions. However, before choosing 24-fiber MPO cable, there are some facts that should be noticed.

The Higher the Fiber Count, the Higher the Loss

Optical loss budget is a big concern among data center managers, and due to limitations in the protocol, standards now require a total connector loss budget of 1.0 dB for 40G and 100G, but a 24-fiber MPO connector typically has a loss of 0.5dB which is much higher than 0.2dB that 12-fiber MPO connector has. This is mainly due to the fact that the more the fiber count, the higher the loss. The higher loss of the 24-fiber MPO limits data center managers to having just two mated pairs in a channel.

Note: Current proper polishing technique can address 24-fiber MPO to meet the low loss requirement as 12 fiber MPO connector. For example, 24-fiber MTP trunk cable in fiber-mart.COM only has 0.35dB insertion loss.

The Higher the Fiber Count, the More Difficult to Control End-Face Geometry

In a quality fiber connector, the fibers protrude slightly beyond the ferrule. When two fibers are mated using the right pressure, the fibers will deform slightly to fill in any gaps and provide a solid mating. Any variance in the pressure can impact the insertion loss and return loss on a fiber-to-fiber basis. To achieve consistence pressure, it is important to have a very flat ferrule after polishing with all the fibers protruding equally. With higher count arrays, like 24-fiber MPOs, there are more fibers to control, which can significantly increase the odds for height variance. For example, in the following 72-fiber array, if we look at this graphic of the middle two rows of fibers, we can see the variance in the height profile. The height variance becomes even more pronounced across more rows of fibers. Besides, it is more difficult to achieve a flat ferrule polishing on a large array area.

Although the polishing technique has been significantly improved, there still exists limitation to achieve a flat end-face and equal pressure over the array.

Standards and Testing Remain an Issue to 24-fiber MPO Cabling

100GBase-SR4 standard has be a reality and that most of users is running 100G over 8 fibers, rather than 20, which will render the 24-fiber MPO a dated interface for 100G Ethernet. In addition, the MPO cabling testing is far more complicated than duplex cabling testing. You have to gain very professional training, tools understanding that you can efficiently conduct multifiber testing. In other words, if there is any issue with the multifiber cabling, it’s not easy to troubleshoot it.

It’s Still Your Choice

With the significant demand for higher speed 40GbE and 100GbE, MPO cabling has become more popular than ever. We have indicated that 24-fiber MPO cable reveals more advantages than 12-fiber MPO cable, however, before choosing it, there are more factors we have talked above that should be taken into consideration.

Mode Conditioning Patch Cable Testing

Mode Conditioning Patch Cable Basics

Mode conditioning patch cables, sometimes also called mode conditioning patch cord (MCP), are built in the form of a simple duplex patch cable. They are designed for Gigabit Ethernet multimode applications at the 1300nm wavelength. Generally, this patch cord consists of a duplex common connector on each end of a cable assembly with a single-mode to multimode of fiber-mart fiber connection in one of the two legs.

In summary, this type of patch cable has three distinctions when compared with common patch cables.

The first one is its structure that we have mentioned above. It features rugged construction with a permanent low profile of fiber-mart closure which helps light go through the fiber core precisely.

The second is the reason why they are needed. Common fiber cables are the medium of light signals. However, when transceiver modules used in Gigabit Ethernet (1000BASE-LX) launch only single-mode (1300 nm) long wave signals, problems arise if an existing network utilizes multimode cables. And then mode condition patch cord comes to aid, making the transmission between single-mode and multimode fibers go on wheel.

The last difference of mode conditioning patch cord is its deployment method. Unlike common fiber cables, mode conditioning patch cord usually needs to be used in pairs. So these cables are usually ordered in even numbers.

Testing Methods of Mode Conditioning Patch Cable

Testing a mode conditioning patch cord for insertion loss is similar to testing any standard fiber cable assembly. If the system in which a mode conditioning patch cord is correctly installed does not function properly, simple steps can be taken to rule out the mode conditioning patch cord as the root cause. Here are the steps.

Testing the Multimode/Multimode Leg of Mode Condition Patch Cord

1. Remove the MCP from the system.

2. Reference out a multimode (MM) test jumper using a 1300nm wavelength multimode source.

3. Verify whether the connector on the receiver (RX) end of the MM reference jumper is good. Connecting the MM reference jumper to the OTS TX, and connecting another same jumper to another OTS RX. Then link the two MM fiber jumpers and measure the insertion loss across the multimode connector pair (just like the following picture shows). This value should be < 0.5 dB.

4. Replace the second MM reference jumper connected to the OTS RX with a multimode/multimode leg of MCP (shown a picture below). Measure insertion loss across this multimode connector pair. This value should be < 0.5 dB too.

Testing the Single-Mode/Multimode Leg of the Mode Conditioning Patch Cord

1. Repeat the same three steps mentioned above to measure the insertion loss across the single-mode connector pair (the value < 0.5 dB). The difference is to do it with two single-mode fiber jumpers.

2. Remove the single-mode jumper from the OTS RX, and then connecting the OTS RX to a MCP cord. Make sure the single-mode fiber part of the MCP connecting with the single-mode reference jumper, like the following picture shows. Measure the insertion loss across the single-mode connector pair.

3. Remove the connector of MCP from the OTS RX, and link the multimode fiber part of the MCP with OTS Rx using a multimode jumper used in the in the previous section. Showing in the below picture.

4. Measure insertion loss. This loss is the insertion loss of the multimode connector pair. This value should be < 0.5 dB.

5. The total insertion loss of the MCP is the sum of the loss across the two connector pairs. If the insertion loss is < 1.0 dB, then the MCP cord is functioning properly.

If the MCP cord was mistakenly reversed in the system, then there will be a very high attenuation (on the magnitude of up to 45.0 dB), which would occur resulting in severely degraded signal strength.

Notes: In the whole testing process, if the insertion loss is not < 0.5 dB, then you should separate connector pair and clean them for the second measurement.


Mode conditioning patch cable provides a convenient and reliable method of connecting multimode fiber plants with 1000Base- LX based transmission equipment compliant with IEEE 802.3 standards. This article introduces a simple method to test mode conditioning patch cable in network system. Hope it may help you.

Attaching More Importance to Fiber Optic Adapter

Fiber optic adapter is a small but critical, part of hardware in the fiber optic cabling system. Available for more than a decade, the fiber optic adapter has been a relatively stable device with no really revolutionary breakthrough in its technology, and its importance is often overshadowed by connectors, but product manufacturers continue to stress the significant role that these devices play in overall interconnection performance.

Getting to Know the Concept of Fiber Optic Adapter

Fiber optic adapter is often used to join two terminated fiber optic cable or pigtails together, or to form a fiber optic jack on a wall plate or panel for patching. Like the copper cable adapter, it creates a permanent mating point somewhere for users to plug into as needed. Fiber optic adapter is also called as fiber coupler, it allows fiber optic patch cables to be attached to each other singly or in a large network, which permits many devices to communicate at once.

Note: fiber optic adapter and fiber optic coupler shape a little differently—if the two fiber assemblies to be connected have different style connectors, then we always call adapter; on the contrast, the two patch cables have the same style connectors, we call adapter. This can be clearly distinguished in the following image.

How Do Fiber Optic Adapter Work?

Unlike a copper connection that two copper conductors can be joined directly by a solder or by connectors that have been crimped or soldered to the wires, the key to a fiber connection is the precise alignment of each fiber core. This alignment is achieved by two precision components: the ferrule within each connector and the alignment sleeve within each adapter as shown below. The alignment sleeve is the critical component in an interconnection, which is aimed to bring together the ferrules of the two connectors being mated within the adapter’s sleeve and at its approximate midpoint. The performance of the adapter, defined as how well it aligns two connector ferrules, is determined by the amount of spring force in, and the tolerance of, the split sleeve.

Three Common Fiber Optic Adapter Types

According to different shapes and structures, fiber optic adapters can be classified in several types, such as bare fiber optic adapter, mating sleeves and hybrid fiber optic adapters. The following text will introduce them respectively.

Bare Fiber Optic Adapter—Bare fiber optic adapter is structured with optical fibers on one side and the adapter on the other side, which is used to link the bare optical fiber cable to fiber optic equipment. The adapter side is a connector that can plug into the devices and enables a quick and easy termination for the optical fiber, making it widely used for emergency situation for fast and temporary fiber optic or urgent connection. According to the connector style on the fiber patch cable, there are LC, SC, FC bare fiber adapters available on the market as shown below.

Mating Sleeve—Mating sleeve means the fiber optic adapter is used to connect the same type of fiber optic connectors as shown in the image below. Bare fiber type and plug-in type are available for the mating sleeve. The LC, SC, FC fiber optic adapter are the common mating sleeve types that we often see in networking applications. LC adapter greatly increases the density of fiber optic connector, SC adapter enables a high precision alignment with a low insertion, return loss and back reflection, and FC adapter is easy to operate but sensitive to dust.

Hybrid Fiber Optic Adapter—Unlike mating sleeve, hybrid fiber optic adapter provides interconnections between two different fiber connector types as shown below. It includes male-female and female-female hybrid fiber adapter. Female-to-female hybrid adapter is with two different ends, which is bulk type hybrid fiber adapter, such as FC female at one end and ST female at the other end. Male-to-female hybrid adapter is built out type with a connector plug end and an adapter socket end. Hybrid fiber adapter is often with compact size and widely used for network environments, integrating different configurations and networks.


Don’t look down upon any components in telecommunication applications, since any small devices play an important role in connection, and improving work efficiency, like fiber optic adapter that we have mentioned above. Choosing the right fiber adapter type, you have to check the fiber optic patch cable you need to connect.

Two Suggestions for Deploying SFP+ Twinax Cable

Have you ever used the Cisco SFP+ twinax copper cable for connecting Cisco switches, as a cost-effective alternative to Cisco SFP+ transceivers for short-distance, high-speed connection? Or choosing other branded SFP+ twinax cables to connect their corresponding devices? In fact, SFP+ twinax cable becomes much more popular than ever before for its lower cost and easier installation than the SFP+ transceiver. You only need to incorporate the SFP+ twinax cables into the physical infrastructure directly, then the connection can be finished without any additional signal processing or conversion. However, although the SFP+ twinax cable is very easy to install, there are still two suggestions you should pay attention to if you choose it to deploy 10G short-distance connection.

Design the Length of the SFP+ Twinax Cables Your Network Needs

Before deploying your 10G short-distance connection, it is very important to design and calculate the length of the SFP+ twinax cables your network needs, avoiding many cables waste or lack of cables when deploying. How to calculate it? Just taking the single 84 in. 45 RU cabinet shown in the following figure as an example. As the cabinet is fitted with 2 top of rack switches and 20 2U servers with dual SFP+ NICs (Network Interface Cards), totally 40 SFP+ twinax cables are required. If you prepare to deploy SFP+ twinax cables in the cabinet, you should firstly calculate the longest connection from the top to the bottom of the cabinet, which is about 7 ft. or 2.1 m, and secondly the connection to any port on either end, approximately 1.5 ft. or 0.45 m. Then you can conclude that the longest cable required to reach the farthest port is 2.1+2×0.45≈3 m. Hence, the 3m SFP+ twinax cable should be long enough to connect any two ports within the cabinet.

Use Cable Management Tools to Support the SFP+ Twinax Cable

Since the bundled cable would be very heavy and tend to sag over time, the cable management tools like cable managers, strain relief bars and cable ties are the vital components to support the SFP+ twinax cables. Firstly, there is no doubt that the cable manager is designed for better cable management, as a very commonly used solution. And secondly, how about the strain relief bar? From its name, it is easy to learn that it is to support the cable by providing strain relief, which also facilitates the correct alignment of cable and connector into the port. Meanwhile, the strain relief bar also has the ability to keep the cables away from the spaces directly behind the server and switch equipment, reducing the thermal resistance through the equipment and promoting the effective cooling and airflow. Thirdly, cable ties should be used to hold the SFP+ twinax cables together and tie them to the strain relief bar and cable manager, although they looks so small and unimportant. What’s more, the cable tie installation should be done carefully to firmly place the cables, so that the cables will not move, and also not so tight as to deform or stress the cable jacket.


We all can’t deny that the SFP+ twinax cable provides an ideal low cost, low power and low latency solution for 10G short-distance connection deployment. In details, the cost of SFP+ twinax cable solution is up to three times less than that of fiber optical solution, the power it consumes is up to 50% less than that of current copper twisted-pair solution, and the latency is also lower than that of current copper twisted-pair solution. Furthermore, it features the smallest 10G form factor, as well as the overall cable diameter, designed for higher density and optimized rack space in 10G uplinks and 10G Fiber Channel SAN and NAS input/output connections. In short, the SFP+ twinax cable is an ideal solution to deploy 10G short-distance connection. If you are decide to deploy it, you are suggested to design and calculate the length of the SFP+ twinax cables your network needs and prepare the cable management tools to support the SFP+ twinax cables.

Considerations About Fiber Optic Cable Installation

It’s true that fiber optic cable, based on optical technology to carry information between two points, have become increasingly important in fiber optic systems. This cable is often attached with the same or different connectors on the ends to connect devices, for example, LC LC multimode patch cord (LCs on both ends). When used in premises, fiber optic cables can be used as backbone cabling in a standard structured cabling network, connecting network hardware in the computer room. And when applied in optimized fiber optic networks, they go directly to the work area with only passive connections in the links. They can be installed indoors or outdoors using several different installation processes. One of my recent blogs has talked about safety issues about fiber optic cable installation. Today, this article still focuses on its installation, but from other aspects, including the general guidelines, its pulling tension, bend radius, and so on.

When deployed outside, fiber optic cables may be direct buried, pulled or blown into conduit or innerduct, or installed aerially between poles. When used outside, they can be e installed in raceways, cable trays, placed in hangers, pulled into conduit or innerduct or blown though special ducts with compressed gas. The installation process depends on the nature of the installation and the type of cables being used.

Installation General Guidelines

First point to mention is that fiber optic cable is often custom-designed for the installation and the manufacturer may have specific instructions on its installation. So, it’s highly recommended to follow the cable manufacturer’s suggestions. Often, it’s necessary to check the cable length to make sure the cable being pulled is long enough for the run, so as to prevent having to splice fiber and provide special protection for the splices. Of course, it’s better to try to complete the installation in one pull. Prior to any installation, one should assess the route carefully to determine the methods of installation and obstacles that are likely to be encountered.

Pulling Tension

Fiber optic cable is designed to be pulled with much greater force than copper wire if pulled correctly, but excess stress may harm the fibers, potentially causing eventual failure. Cable manufacturers install special strength members, usually aramid yarn, for pulling. Fiber optic cable should only be pulled by these strength members. Any other method may put stress on the fibers and harm them. During installation, swivel pulling eyes should be used to attach the pulling rope or tape to the cable to prevent cable twisting during the pull.

Besides, cables should not be pulled by the jacket unless it is specifically approved by the cable manufacturers and an approved cable grip is used. Tight buffer cable can be pulled by the jacket in premises applications if a large (~40 cm, 8 in.) spool is used as a pulling mandrel. It’s right to wrap the cable around the spool 5 times and hold gently when pulling.

It’s ill-advised to exceed the maximum pulling tension rating. It’s suggested to consult the cable manufacturer and suppliers of conduit, innerduct, and cable lubricants for guidelines on tension ratings and lubricant use.

On long runs (up to approximately 3 miles or 5 kilometers), one should use proper lubricants and make sure they are compatible with the cable jacket. If possible, an automated puller can be used with tension control and/or a breakaway pulling eye. On very long runs (farther than approximately 2.5 miles or 4 kilometers), one should pull from the middle out to both ends or use an automated fiber puller at intermediate point(s) for a continuous pull.

Bend Radius

When there are no specific recommendations from the cable manufacturer, the cable should not be pulled over a bend radius smaller than twenty (20) times the cable diameter. And after completion of the pull, the cable should not have any bend radius smaller than ten times the cable diameter.

Twisting cable

It’s known that twisting the cable can stress the fibers, thus in no case should one twist the cable. (Tension on the cable and pulling ropes can cause twisting.)

Use a swivel pulling eye to connect the pull rope to the cable to prevent pulling tension causing twisting forces on the cable.

Roll the cable off the spool instead of spinning it off the spool end to prevent putting a twist in the cable for every turn on the spool.

When laying cable out for a long pull, use a “figure 8” on the ground to prevent twisting. The figure 8 puts a half twist in on one side of the 8 and takes it out on the other, preventing twists.


Fiber optic cables have been widely deployed for computer net- works (LANs), closed circuit TV (video), voice links (telephone, intercom, audio), building management, security or fire alarm systems, or any other communications link. With its installation in large scale, it’s of great importance to know some basic points on cable installation discussed in this text. As for the fiber optic cables chosen for project, you can try Fiberstore, whose cables are available in many types, like SC fiber optic cable, LC SC cable, MTP cable. All are test- and quality-assured, suitable for both indoor and outdoor installation.

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