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

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

Singlemode QSFP+ vs. Multimode QSFP+

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

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

Which One to Choose, Singlemode or Multimode?

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

Notes for Using Singlemode QSFP+ and Multimode QSFP+

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

Conclusion

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

Are You Ready for 40G and 100G?

Data centers regularly undertake their own great migration, to ever higher speed networks. 10G, unimaginable a decade ago, is now common in larger enterprises. And now many enterprises have to adopt 40 Gigabit Ethernet or even 100G in the aggregation and core layers of data center networks in order to meet the overall bandwidth demands of top-of-rack servers. The need is clear: a 40/100G Ethernet migration plan is quickly becoming a matter of survival. Is your network cabling optimized for this inevitable growth? Are you ready for 40G and 100G?

Fiber Transmissions at Higher Speeds

When moving to 40/100GbE, the most important difference in backbone and horizontal multimode applications is the number of fiber strands. 40GBASE-SR4 uses 8 strands in total, 4 strands to transmit and 4 to receive. 100GBASE-SR10 uses 10 lanes to transmit and another 10 lanes to receive for a total of 20 strands. In data centers and backbones, it may be possible to have 8 or 20 individual strands of fiber. However, those strands may take disparate paths from one end to the other and this can cause delay skew (known as bit skew) resulting in bit errors. For this reason, the 40/100GbE standards are written around fiber optic trunk assemblies that utilize a MPO/MTP multi-fiber array connector. Data is transmitted and received simultaneously on MTP interfaces through 10G simplex transmission over each individual strand of the array cable. In these assemblies, all strands are the same length. Also referred to as "parallel optics", this construction minimizes bit/delay skew, allowing the receive modules to receive each fibers information at virtually the same time.

Copper Transmissions at Higher Speeds

The first 10GbE capable copper interface was developed for the 10GBASE-CX4 application. The physical requirements for this shielded four-lane copper connector is standardized under SFF-8470. As a passive assembly, the SFF-8470/CX4 cables have a reach of 15m. This assembly supports 10GbE, InfiniBand, FibreChannel and FCoE. These assemblies use twinax cable, constructed of two inner conductors with an overall foil covered by a braid shield. Due to their low latency, these cables are popular in supercomputing clusters, High Performance Computing and storage. As part of the 802.3ba 40/100GbE standard, multi-lane 40GBASE-CR4 and 100GBASE-CR10 was defined. This standard specifies the use of 4 and 10-lane twinax assemblies to achieve 40 and 100GbE speeds for distances up to 7m.

40/100G MPO/MTP System

MPO/MTP is available in both 12 and 24 strand termination configurations used at the end of a trunk assembly. A modular laser optimized multimode MPO/MTP system that supports 40G and 100G fiber optic networks includes trunks, harnesses, array cords, modules, and adapter plates. For 40GbE, a 12-fiber cabling solution with each channel featuring four dedicated transmit fibers and four dedicated receiver fibers is used. In general, the middle four fiber remain unused. Parallel transmission is also used for 100GbE with a 24-fiber solution or two 12-fiber solution.

At present, 40GbE is taking over from 10GbE as the new high-growth market segment. Meanwhile, the 40GbE optics are universal in data center and the market of 100GbE is accelerating. Being prepared for 40/100G is essential: within a few short years higher-speed Ethernet will be common in data centers across all types of organizations. Fiberstore is ready. Fiberstore offers various optical communication products to meet diverse demands. For example, we provide 40GBASE-SR4 QSFP+ transceivers, like Finisar FTL410QE2C 40GBASE-SR4 QSFP+ transceiver and Mellanox MC2210411-SR4 40GBASE-SR4 QSFP+ transceiver, which are branded by famous companies and quality guaranteed.