MPO/MTP Technology for 40GbE Parallel Optic Solutions

Nowadays, data centers are witnessing a rise in the number of network connections, and it’s necessary for data centers to achieve even higher-density in both ports and cabling to accommodate the bandwidth demands. Parallel optics combining the use of cables and fiber optics serve as the medium to satisfy the growing need for transmission speed and data volume.

Multi-fiber connectors bring together 12 or 24 fibers in a single interface just as compact as a RJ45 connector. The multi-fiber push-on or also multi-path push-on (MPO) technology and especially the MTP connectors from the manufacturer US Conec have proven themselves as a practical solution for high-performance data networks in data centers. This paper mainly introduces MPO/MTP technology, and parallel optics which utilizes this multi-mode connectors in 40 Gigabit Ethernet (GbE) transmission.

Before going into the main body, a table showing the 40GbE standard, cable types and maximum allowable distances is below.

Transmission technology Cable type Signal Rate Maximum distance
40GBASE-KR4 PCB (bus) 4 x 10 Gb/s 1 m
40GBASE-CR4 Copper, Twinax 4 x 10 Gb/s 7 m
40GBASE-SR4 OM3, OM4 4 x 10 Gb/s OM3 100m, OM4 150m
40GBASE-LR4 Single-mode Fiber 4 x 10 Gb/s 10 km
How MPO/MTP Comes out?

As is shown in the table, while establishing 40GbE links, parallel optical channels with multi-mode fiber (MMFs) of the categories OM3 and OM4 are used. The ports have to accommodate four or even ten times the number of connectors. This large number of connectors can no longer be covered with conventional individual connectors, which explain the reason why the 802.3ba standard incorporated the MPO multi-fiber connector for 40GBASE-SR4 and 100GBASE-SR10. It can contact 12 or 24 fibers while saving space.

MPO Connectors Structure

IEC 61754-7 and TIA/EIA 604-5 defined MPO connector that can accommodate up to 72 fibers in the tiniest of spaces, most commonly used for 12 or 24 fibers. This MPO connector is designed for the high-density connection of MMFs, allowing easy connection and disconnection. MPO connector has two alignment pins to align the ferrule, and a clamp spring. When closed, the MT connector is extremely compact and is thus well suited for high-density fiber connection within closures or cabinets. The kind of multi-mode connector combines high-density connection with convenient disconnecting action, ideal in satisfying the need for high-density packaging in equipment. In 40G links, QSFP+ transceivers use MPO connectors as the interface for high performance. Just like, this HP JG709A 40GBASE-CSR4 QSFP+ transceiver listed on FS.COM achieves 300m link length with MPO connector.


Laser-optimized MMF OM3 and OM4 for 40G Solution

Category OM3 and OM4 MMF are the future-proof cabling choices for 40G links. Lasers are used for OM3 and OM4. These lasers are generally vertical-cavity surface-emitting lasers (VCSELs) which are cheaper than distributed feedback lasers. The VCSELs are able to transmit data at higher rates. According to the table shown above, OM3 has a link length of 100 meters so it supports about 85 percent of all data center channels depending on architecture and size, and OM4 fibers have a link length of 150 meters so they cover nearly 100 percent of the required reach.

Parallel Optical Channels in 40G Links

As noted in the table, the 802.3ba standard defines the parallel operation of four OM3/OM4 fibers for 40GbE in 40GBASE-SR4. Two fibers have to be used per link because this arrangement is full duplex operation, i.e. Simultaneous transmission in both directions. Therefore the number of fibers increases to eight for 40GBASE-SR4. That is four of the twelve fibers remain unused and eight of the twelve fibers are used in each case in connection with 12-fiber and MPO connectors. In the parallel optical link, the signal is split, transmitted over separate fibers and then joined again. That means the individual signals have to arrive at the receiver at the same time.


MPO/MTP technology is performance- and quality-assured as a trend for decision makers in to carefully plan their fiber optics infrastructure for 40GbE transmission. FS.COM provides not only high-quality MPOMTP connectors, but also MPO-based patch cables (eg. Push-Pull MPO cable). You can visit FS.COM for more information about MPO connectors and MPO-based cables.

MPO/MTP Technology Overview

Along with the development of fiber technologies over the past a couple of years, tools for easier fiber connection have been invented—fiber optic connectors (or so-called “better mousetrap”). Given there are various fiber optic connectors (eg. ST, SC, LC, MPO/MTP) available for network designers to set up fiber connectivity in bandwidth-demanding applications, this article introduces MPO/MTP in details.

MPO/MTP technology with multi-fiber connectors ensures ideal conditions for establishing high-performance and high-speed data networks to handle bandwidth requirements. The term MTP is a registered trademark of US Conec used to describe their connector. The US Conec MTP product is fully compliant with the MPO standards. As such, the MTP connector is a MPO connector. The following passages will mention MPO only instead of MPO/MTP for simplicity. To let readers gain a better understanding of MPO technology, MPO components introduction goes first followed by the applications of MPO technology.

MPO Components

MPO (multi-position optical) connector contains up to 24 fibers in a single connection. It’s available in a male version (with pins) or a female version (without pins). The pins ensure that the fronts of the connectors are exactly aligned on contact and that the endfaces of the fibers are not offset. MPO connector components mainly contain two parts: adapter and cable.

MPO Adapters

There are two types of MPO adapters based on the placement of the key: key-up to key-down, and key-up to key-up. In the former type, the key is up on one side and down on the other. The two connectors are connected turned 180° in relation to each other. In the latter type, both keys are up. The two connectors are connected in the same position in relation to each other. Just like what’s shown in the figure below.

MPO Cables

MPO fiber cables are available in two primary types: MPO trunk cables and MPO harness cables.

MPO trunk cables are available in 12-144 counts. They serve as a backbone connecting the MPO modules to each other, intended for high-density applications.

MPO harness cables, also called MPO breakout cables or MPO fanout cables, are available in 8-144 counts. As terminated with MTP/MPO connectors on one end and standard LC/FC/SC/ST/MTRJ connectors (generally MTP to LC) on the other end, MPO harness cables provide a transition from multi-fiber cables to individual fibers or duplex connectors.

MPO Applications: 10 GbE to 40 GbE/100 GbE Migration

The remaining parts describe how MPO technology is utilized to permit successful migration from 10 GbE to 40/100 GbE.

It’s no doubt that converting or expanding existing infrastructure to accommodate higher bandwidth applications is more ideal and practical in data centers. In 10 GbE to 40 GbE/100 GbE migration, the most key point that should be kept in mind is the capacity expansion in which MPO modules are used to enable faster transmission. Many 40G QSFP transceiver modules utilize MPO technology for 40G links, among which the Cisco QSFP is the most widely-used module. Take Cisco for example, QSFP-40G-SR4 realizes 40G links over 850nm multi-mode fiber (MMF) with MPO-12 as its connector type.

In 40G to 100G migration, there requires the use of 24-fiber MPO cables. The existing 12-fiber connection can either be expanded with the addition of a second 12-fiber connection or can be replaced with the installation of a 24 fiber connection.


With these MPO components and technology applications, it’s easier for network designers to select the right MPO types to meet the bandwidth requirements. As a professional fiber optical product manufacturer and supplier, Fiberstore supplies various MPO modules and cables, including QSFP-40G-SR4 (one of Cisco QSFP products) mentioned above. You can visit Fiberstore for more information about MPO modules.