40G Solutions: Duplex Fiber or MPO/MTP Fiber?

There’s been a lot of talk lately surrounding bidirectional 40 Gb/s duplex applications, or BiDi for short. Currently offered as a solution by Cisco®, BiDi runs over duplex OM3 or OM4 multimode fiber using QSFP modules and wavelength division multiplexing (WDM) technology. It features two 20 Gb/s channels, each transmitting and receiving simultaneously over two wavelengths on a single fiber strand – one direction transmitting in the 832 to 868 nanometer (nm) wavelength range and the other receiving in the 882 to 918 nm wavelength range. Avago Technologies also offers a similar QSFP BiDi transceiver.

Unidirectional 40 Gb/s duplex fiber solutions are available from Arista and Juniper. These differ from the BiDi solution in that they combine four 10 Gb/s channels at different wavelengths – 1270, 1290, 1310, and 1330 nm – over a duplex LC connector using OM3 or OM4 multimode or singlemode fiber. These unidirectional solutions are not interoperable with BiDi solutions because they use different WDM technology and operate within different wavelength ranges.

40G Solutions

While some of the transceivers used with these 40 Gb/s duplex fiber solutions are compliant with QSFP specifications and based on the IEEE 40GBASE- LR4 standard, there are currently no existing industry standards for 40 Gb/s duplex fiber applications using multiple wavelengths over multimode fiber – either bidirectional or unidirectional. There are standards-based 40 Gb/s applications over duplex singlemode fiber using WDM technology, but standards-based 40 Gb/s and 100 Gb/s applications over multimode use multi-fiber MPO/MTP connectors and parallel optics (40GBASE-SR4 and 100GBASE-SR4).

40 Gb/s duplex fiber solutions are promoted as offering reduced cost and installation time for quick migration to 40 Gb/s applications due to the ability to reuse the existing duplex 10 Gb/s fiber infrastructure for 40 Gb/s without having to implement MPO/MTP solutions. However, some of the concerns surrounding these non-standards based 40 Gb/s duplex fiber solutions include:

  • Lack of standards compliance and lack of interoperability with standards-based fiber solutions
  • Risk of being locked into a sole-sourced/proprietary solution that may have limited future support
  • BiDi and other 40 Gb/s duplex transceivers require significantly more power than standards-based solutions
  • Lack of application assurance due to operation outside of the optimal OM3/OM4 wavelength of 850 nm
  • Limited operating temperature range compared to standards-based solutions

Due to the aforementioned risks and limitations of using non-standards-based 40 Gb/s duplex fiber solutions, we recommends following industry standards and deploying 40GBASE-SR4 for 40 Gb/s applications today. While this standard requires multiple fibers using an MPO/MTP-based solution, it offers complete application assurance and interoperability, as well as overall lower power consumption.

Furthermore, TIA and IEC standards development is currently underway for wideband multimode fiber (WBMMF), which is expected to result in a new fiber type (potentially OM5 or OM4WB) that expands the capacity of multimode fiber over a wider range of wavelengths to support WDM technology. While not set in stone, the wavelengths being discussed within TIA working groups are 850, 880, 910, and 940 nm.

Unlike current 40 Gb/s duplex fiber applications, WBMMF will be a standards-based, interoperable technology that will be backwards compatible with existing OM4 fiber applications. WBMMF is expected to support unidirectional duplex 100 Gb/s fiber links using 25 Gb/s channels on 4 different wavelengths. WBMMF will also support 400 Gb/s using 25 Gb/s channels on 4 different wavelengths over 8 fibers, enabling existing MPO/MTP connectivity to be leveraged for seamless migration from current standards-based 40 Gb/s and 100 Gb/s applications to future standards-based 400 Gb/s applications.

Differences Between 12-fiber and 24-fiber MTP/MPO Connectivity

24-fiber MTPSince IEEE 802.3ba 40GBASE-SR4 and 100GBASE-SR10 were ratified in 2010, many have looked to 24-fiber connectivity as the ideal migration solution in the data center. Using 24-fiber cabling throughout an entire channel provides extra flexibility, as users can easily migrate from 10G to 40G or 100G by simply swapping out the connectivity at the end of the channel. Pre-terminated cabling using 24-fiber connectors provides double the density of 12-fiber cabling in the same footprint, reducing the cabling required, allowing for fewer cable pathways, and improving airflow in data centers. With the growth of 24-fiber MPO/MTP solutions, some confusion and misinformation has emerged within industry circles. Especially, the differences between 12-fiber and 24-fiber MTP/MPO connectivity.

24-Fiber MTP/MPO Connectivity Is More Suitable for 100G than 12-Fiber

The current IEEE 802.3ba 100GBASE-SR10 standard defines 100GbE using 10 lanes of multimode fiber at 10 Gb/s. Progress has indeed been made in delivering 100 GbE over fewer lanes, and the IEEE 802.3bm task force is developing a new standard that would use 4 lanes of multimode fiber at 25 Gb/s per lane. This 4×25 solution would only require 8 fibers (4 transmit, 4 receive) — the same as the current 40GBASE-SR4. That means a 12-fiber MPO/MTP connector can support a single 100G channel. However, a 12-fiber connector for an 8-fiber channel is inefficient, as 4 strands in the 12-fiber connector are not used. Alternatively, by using a 24-fiber MTP connector in the horizontal cabling, it can then be converted into three 8-fiber 100G channels that run over one cable, with all 24 fibers used to support traffic.

12-fiber and 24-fiber MTPMPO

Let’s look at another example. Say you need to support twelve 100GbE channels using the next gen 4×25 Gb/s standard. With the 12-fiber MPO/MTP connectors, you would need to install 12 connectors, or 144 fibers total, with 33% of the fiber wasted. However, when supporting the same 12 channels with 24-fiber connectors, only 4 cables would be required, using 96 fibers total, at 100% fiber utilization. The 24-fiber MPO/MTP channel solution allows the use of the ratified 100GBASE-SR10 20-fiber technology today, while at the same time maximizing the installed infrastructure investment in the event of 4×25 Gb/s ratification and ultimate implementation. Choosing a 12-fiber connector strategy simply does not accomplish this. It drives down return on investment and subsequently increases the total cost of ownership. This is the exact opposite of the design intent of a data center infrastructure system.

24-Fiber Connectors Have Less Insertion Loss Than 12-Fiber Connectors

Insertion loss is a critical performance parameter in data center cabling deployments. Lower overall optical loss allows more margin for the network to operate, or in the case for some users, offers the option of more connections for patching locations. The IEEE 802.3ba 40/100GbE standard specifies OM3 fiber to a 100-meter distance with a 1.5 dB total connector loss budget. OM4 fiber for 40/100GbE is specified to a 150-meter distance with a 1.0 dB total connector loss budget. As total connector loss increates, the supportable distance at that data rate decreases. However, with the current trend of moving to distributed access/aggregation data center switch strategies such as Top of Rack (ToR), the prevalence of backbone lengths exceeding 100 meters is dramatically decreasing.

Some have mistakenly claimed that higher fiber count leads to higher loss, and one cable vendor pointed to a “typical” loss of 0.5 dB for 24-fiber connectors as evidence. In fact, the industry standard product rating for MPO/MTP connector performance of both 12-fiber and 24-fiber is 0.5 dB maximum. When using proper polishing techniques, 24-fiber MPO/MTP terminations can meet the same performance levels as 12-fiber assemblies. Improved performance can be achieved using low-loss ferrules for both 12-fiber and 24-fiber MPO/MTP connectors rated at 0.35 dB maximum.


As explained above, the ability to achieve the same performance in both 12-fiber and 24-fiber MPO/MTP assemblies, coupled with the clear migration advantages of using 24-fiber based components, creates a compelling argument for making 24-fiber MTP the connector of choice. We also understand that many aspects of data centers are unique to each client, designed around not just “cable and connectors”, but also inclusive of variables such as facility purpose and administrative styles. Any vendor is well advised to listen to the client and view this complex environment as a total ecosystem—inclusive of many external drivers. This is why Fiberstore also offers a full end-to-end 12-fiber MTP solutions alongside our 24-fiber end-to-end solution. We believe that providing options to our clients is paramount to meeting their unique needs.

High-density Cabling With MTP/MPO Connectors

With the expected increase in use of 40 Gbps and 100 Gbps, there is an increasing demand for higher and higher density fiber cabling solutions. Existing and emerging network technologies are driving the need for increased data rates and fiber usage in the data center. High-density cabling with MTP/MPO connectors is essential to address these trends to provide an easy migration from duplex fiber serial transmission to 12- and 24-fiber parallel optics transmission.

What Is MTP / MPO Connector

The MPO connector is a multi-fiber connector defined according to IEC 61754-7 and TIA/EIA 604-5 that can accommodate up to 72 fibers in the tiniest of spaces, comparable to an RJ45 connector. MPO connectors are most commonly used for 12 or 24 fibers. To achieve lower tolerances and better attenuation values, the US Conec developed the MTP connector which has better optical and mechanical quality than the MPO. MTP/MPO connectors provide the following benefits:

  • A single 12 fiber connector at one end connects to multiple duplex connectors at the other end such as LC or SC
  • Linking cables can be pre-connected to modules which are then placed in patch panels above the equipment
  • Modules can be replaced and upgraded if required
  • Scalable and adaptive to technology changes
  • Module can be replaced with a fan-out and adapter plate if required
MTP / MPO Cable Assemblies

Since field termination is becoming widely available, MTP/MPO technology and MTP/MPO cable assemblies listed below are becoming more and more popular.

MTP / MPO Trunk Cable

MTP/MPO trunk cables are terminated with the MTP/MPO connectors. Trunk cables are available with 12, 24, 48 and 72 fibers. MTP/MPO trunk cables are designed for data center applications. The plug and play solutions uses micro core cable to maximize bend radius and minimize cable weight and size.

MTP / MPO Cable Harness

MTP / MPO cable harness is also called MTP / MPO breakout cable or MTP / MPO fan-out cable. This cable has a single MTP connector on one end That breaks out into 6 or 12 connectors (LC, SC, ST, etc.). The MTP / MPO harness assembly has Become a popular method for connections into high-port-count network switches.

Push-Pull MTP / MPO Patch Cable

A push and pull cable has the same components and internal-structure as the traditional patch cords, except a tab attached to the connector used for pushing or pulling the whole connector. This small push-pull tab looks simple but it is functional for high density cabling in 40/100G migration. The Push-Pull MTP/MPO patch cable for highest density allows high-density MTP presentation underneath SAN switches or proximate to super computers. It also provides access to 192 MTP connections in 2U of height space.


The Trend for High-density Cabling

MTP/MPO style pre-terminated cables offer a market-leading low loss, fast and efficient connection system particularly suited to the data center and storage area network environment. The following factors lead to the trend for high-density cabling:

  • Reduced cable size and increased air-flow to equipment
  • High Density blade servers with hundreds of ports
  • Virtualisation and cloud-computing
  • High real-estate costs for rack space
  • Reduced installation times
  • Structured cabling approach (zone approach)
  • 40G and 100G parallel optics

Fiberstore offers you a wide selection of MTP/MPO style pre-terminated cables including MTP/MPO trunk cable, MTP/MPO harness cable, Push-Pull MTP/MPO patch cable. Besides, we also provide Push-Pull tab LC patch cord and other related fiber cables. All these cables are with high flexibility and reliability. They can be customized according to your special requirements.

Important Components for 40/100G Ethernet Migration

With the growth of bandwidth-intensive applications such as high-performance computing and business continuity, there emerge higher-speed networks of 40/100G Ethernet. And as products become less expensive and more available over time, 40/100G Ethernet will inevitably be commonplace in our daily life. Therefore, it is necessary to create a migration path by installing a structured cabling system that can support the future 40/100G networking needs. In this system, such fiber optic products as MTP/MPO assemblies, 40/100G transceivers and 40/100G direct attach cables (DACs) are important components. This article will discuss their roles in 40/100G Ethernet migration respectively.

MTP/MPO Assemblies

Since 40/100G Ethernet uses parallel optics technology which requires data transmission across multiple fibers simultaneously, the multi-fiber connectors are needed. MTP/MPO is the designated interface for multi-mode 40/100G Ethernet, and its backward is compatible with legacy 1G/10G applications as well. 40G Ethernet uses a 12 position MTP/MPO connector interface that aligns 12 fibers in a single row. And the 4 leftmost fibers are used to transmit data, the middle 4 fibers are left unused, while the 4 rightmost fibers are used to receive data. 100G Ethernet uses a 24 position MTP/MPO connector with two rows of 12 fibers. And the outermost fibers on either end of the rows are vacant, while 10 fibers in the upper row for transmitting data and the remaining 10 fibers in the lower row for receiving data.

optical lane assignments

40/100G Transceivers

Together with MTP/MPO connectors, 40/100G transceivers are often used (as shown in the above figure). Through the use of plug-and-play, hot-swap transceiver miniaturization, fiber connectivity in higher-speed active equipment is being condensed and simplified. Transceivers used in 40/100G Ethernet migration include 40G QSFP+ transceivers, 100G CFP transceivers and so on. 40G QSFP+ transceivers can support 4x10G modes, which allow new parallel optics active equipment being compatible with existing 10G transceivers. And the electrical connection of a 100G CFP transceiver uses 10x10G lanes in RX (receive) and TX (transmit) direction, supporting both 10x10G and 4x25G variants of 100G interconnects.

40/100G DACs

To save cost, 40/100G DACs are often used in 40/100G Ethernet instead of optical transceivers. Applied to short reach applications, it is a fixed assembly supporting high speed data that uses a small form-factor connector module as an optical transceiver on each end of a length of cable. The modules on each end meet small form-factor standards and have some function of the optical transceivers, meaning that DAC inherits some advantages of the small form-factor module. Thus, sometime there is no need to upgrade the equipment by using a DAC.

To meet the future 40/100G networking needs, the cabling system shall include components that not only support future high-bandwidth applications but also be compliant to 1G and 10G applications and all current and anticipated industry standards. Meeting all these requirements, the above mentioned MTP/MPO connectors, 40/100G transceivers and 40/100G DACs play important roles in migration to 40/100G Ethernet. As a professional supplier of fiber connectivity network solutions, Fiberstore supplies all these fiber optic products and other kinds of products for 40/100G Ethernet migration.

The development of MPO optic fiber communication systems

In recent years, in order to adapt high speed and large capacity optical fiber communication systems the high density and high efficiency cabling connecting needs, there are two companies in Japan have developed and research in MTO or MTP fiber connectors.

Based on such as high speed and large capacity of DWDM optical fiber communication systems has a large number of using, fiber optic connector is an important part of DWDM technology although in the past single core SC connectors has been widely adopted. And recent years, the demand for multi-fiber high-density connector DWDM system has improved. Now the most popular 8 fiber mtp mpo connector sm optical density is about five times as the SC connectors. Optical fiber connector affect the reliability and the performance of optical transmission system.

When fiber optic cable introduced from outside, fiber optic cable need to be welded in the fiber cassette, is also called terminal box. while for example, fiber optic MPO cassette 12 fibers , with SC,LC,ST, FC connectors, is a highly flexible fiber management unit that can be used stand alone or integrated into the MPO fiber optic patch panels. And before this, MPO/MTP fiber optic patch cord need to connect optical transceiver and terminal box.

The new technology is that high-end pick density of MPO fiber system can increase the number of core optic fiber and the use of fiber optic connectors, no longer just 12 fibers or 24fibers, it might be 72 fibers. Then if we can accurately calculate the length of the fiber optic cable, we will save a lot of time.


MTP/MPO high-density wiring system will be high density optical fiber connector and the ribbon cable in the factory to complete the termination, testing, and equipment at the scene, plug and play, support the rapid deployment, user data center is the increasing data center under the background of high capacity wiring needs ideal solution, with simple installation, construction fast, compact design, high precision, plug and play, etc.

With the improving of the network speed, in terms of optical fiber, correlates twin-core fiber can support MB, gigabit application, but without the use of special coding and agreement, it is difficult to support the 40G and 100G two core optical fiber, and a single channel of 4 core or 10 core optical fiber, 40G and 100G in normal optical fiber communication networks just like the 8 core optical fiber and 20 core optical fiber, it brought more challenge to the traditional data communication , so we will need to use high-density optical fiber. and except that, the important reason is the familiar optical fiber connectors, such as SC, LC no matter from some conclusions and miniaturization can satisfy the high-speed Internet standards are defined in the MDI multi-fiber requirements, and completing single fiber of multi-fiber links live is very difficult, because of a core of unqualified means the whole root is unqualified.

If you have any problem about optic fiber communication products, welcome to visit our store.Here is the website. http://www.fiberstore.com/

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