How QSFP+ 40GBASE-iSR4 Optics Is Developed

In response to the increasing bandwidth demands facing data centers, network designers are paving the way for the introduction of 40Gbqs operations. Owing to this, telecommunication vendors continuously expand the portfolio of innovative parallel fiber optic transceivers to increase the 40G performance, resulting in 40G QSFP+ transceivers becoming the shining star on the market. 40G QSFP+ 40GBASE-iSR4 optics is the newly evolved products for 40G connectivity, but opportunity always besides with challenges. As people are so concerned about the future of their network, understanding the 40GBASE-iSR4 QSFP+ will be helpful for future high-performance Ethernet needs.

Why Move to 40G Ethernet Network

The volume of digital information flowing through data network develops at an ever increasing rate day by day. So the growth of cloud computing, server virtualization and the trend toward network convergence is forcing today’s networks to be more efficient and faster than ever. 1Gbps Ethernet access links have been replaced by 10Gbps links due to the increases in server utilization obtained through Virtualization. To keep up, higher performance switching hardware is needed to provide sufficient I/O (Input/Output) bandwidth to avoid blocking. In order to meet this demand, many newer access switches could support 48 ports of 10G Ethernet for connection to downstream servers, and 2 or 4 ports of 40G Ethernet for connection to the core switches. These 40G interconnects are implemented by using QSFP+ transceivers and could provide sufficient bandwidth to enable fully non-blocking switch fabrics.

QSFP+ is featured with various advantages like delivering excellent high speed optical/electrical performance coupled with low power dissipation. In addition, with bundled fiber cables and MPO connectors, the port density of QSFP+ modules is triple that of SFP+ modules. Moreover, the power consumption is reduced from 1000 mW maximum per lane for SFP+ to 375 mW maximum per lane for QSFP+. 40GBASE-iSR4 QSFP+ module like AFBR-79EIDZ is not only 40Gb Ethernet compliant, but also inter-operable with any 10GBASE-SR compliant transceiver at link distances up to 100 meters over OM3 multimode fiber. The letter “i” in 40GBASE-iSR4 QSFP+ refers to the ability of inter-operation. AFBR-79EIDZ see in Figure 1 is Avago 40GBASE-iSR4 QSFP+ transceiver available on the market. Just as any other modules, this Avago QSFP+ iSR4 is designed to be fully compatible with the 40GBASE-SR4 specification. It’s capable of inter-operating with legacy 10GBASE-SR transceivers.

40GBASE-iSR4 QSFP+—an Cost-Effective Solution

40GBASE-iSR4 QSFP+ transceiver was released to tackle the issue of an overload condition when connecting a 40GBASE-SR4 transmitter to a 10GBASE-SR receiver. It is intended to be fully compliant to the 40GBASE-SR4 specification but with a lower maximum transmit optical output power. The maximum specified output power has been lowered from +2.4 dBm to -1 dBm allowing it to interface with 10GBASE-SR receivers without fear of overload.

The VCSEL design combined with superior laser programming and control algorithms allow for a reduction in the module maximum specified optical output power without compromising any of the module high speed electro-optic performance. And the result (see in Figure 2) is a fully compliant 40GBASE-SR4 module like QSFP-40G-SR4 which can interoperate with legacy 10GBASE-SR transceivers. For further understanding of the 40GBASE-iSR4 optics, it is advisable for you to take a glance at the development of it.

Standardization of 40GBASE-iSR4

The release of IEEE 802.3ba-2010 standard for 40G Ethernet specifies the optical and electrical requirements for various physical layer link implementations. The 40GBASE-SR4 PMD (physical medium dependent) variant defines a 4-lane parallel optical interconnect for operation over OM3 multimode fiber with transmission distance up to 100 meters. Each of the four lanes works at a data rate of 10.3125 Gbps which is the same serial bit rate that was defined for 10G Ethernet links.

The 40GBASE-SR4 PMD addresses the need for 40Gbps interconnects in the data center. It takes advantage of the widely-deployed and low-cost 850nm VCSEL (vertical cavity surface emitting laser) technology. Because each of the 4 lanes in 40GBASE-SR4 have the same serial bit rate of 10G Ethernet link, there is an opportunity for switching hardware vendors to utilize 40GBASE-SR4 as 4 separate 10G Ethernet interconnects.

Challenge Hindering the Development

The standard of 40GBASE-SR4 provides an opportunity to further address the growing need for bandwidth. It is not defined to be backward compatible with the preceding 10G Ethernet short reach interconnect standard. Although both 40G Ethernet and 10G Ethernet included a PMD definition for short reach VCSEL based optical links operating at 10.3125 Gbps per lane, interoperability cannot be guaranteed.

The following analysis of 40GBASE-SR4 and 10GBASE-SR specifications tells why inter-operability cannot be guaranteed over all specified operating conditions.

From the above chart, we could see that many of the transmitter and receiver specifications governing the 10GBASE-SR standard are equal or more stringent than those for 40GBASE-SR4 standard. This is not surprising because the 40GBASE-SR4 specification is written to cover transmission links up to 100 meters, while the 10GBASE-SR specification is intended to satisfy a maximum transmission link length of 300 meters over OM3 multimode fiber. Except the distance, the main specification gap preventing guaranteed inter-operability relates to receiver overload.

Summary

40GBASE-iSR4 QSFP+ proves itself as a suitable solution for designers to mount their network capacity. QSFP+ iSR4 optics is able to support standard 40G Ethernet links up to 100 meters over OM3 and 10GBASE-SR links over the same distances. FS.COM offers a variety of 40G QSFP+ modules for you to choose from. The Avago compatible QSFP+ 40GBASE-iSR4 modules are also provided. For more information about Avago QSFP+, you van visit us.

How to Minimize the limitations on the Transmission Distance

Transmission distance is the NO.1 factor that designers would take into account when deploying network because the exact transmission distance that fiber optic can support is usually limited by many factors. How to avoid this situation? Is there a method that can help us to achieve long transmission distance? This article today will pay attention to the factors that limit optical transmission distance and provide some practical solutions accordingly.

Optical Cable Type
The maximum transmission distance of fiber optic cable (single-mode or multi-mode fiber) is typical limited by dispersion. Multi-mode transmission is affected by the modal dispersion, while single-mode fiber is limited by chromatic dispersion. The core of the single-mode fiber optic is much smaller than that of multi-mode fiber. That’s why single-mode can transmit over longer distance than multi-mode fiber. Most designers should attach importance to review the specifications and limitations of transceivers and have them work optimally in their devices. Then it is highly recommended that we use multi-mode fiber optic transceivers for shorter distances and single-mode fiber for long distance transceivers. Take QFX-QSFP-40G-SR4 as an example, it is the compatible Juniper 40GBASE-SR4 QSFP+ transceiver that operates over multi-mode fiber. Although our application may call for an long reach, we can only use multi-mode fiber on this module for a distance of 150m. If you use an single-mode fiber on this transceiver, it may cause an error.

Light Source of Fiber Optic Transceiver
Optical signals must be converted into electronic signals over the optical transceiver because most of the devices are electric based. And the conversion between them is largely depend on a LED (light emitting diode) or a laser diode inside the optical transceiver. Fabry Perot (FP) laser, Distributed Feedback (DFB) laser and Vertical-Cavity Surface-Emitting (VCSEL) laser are the common type of light source inside the transceiver module that may have an impact on optical transmission distance. Table 1 present a comparison between these light sources, which would be a factor that designers should take into account when picking an optical transceiver to achieve long transceiver distance.

Splice and Optical Connectors
The signal loss can be caused when passing through fibers or connector, which will largely affect the transmission distance. Fusion splicing is the method of joining two optical fibers end-to-end using heat. Alternatives to fusion splicing include using optical fiber connectors or mechanical splices both of which have in general higher insertion losses, lower reliability and higher return losses than fusion splicing. Network designers nowadays choose to use fusion splicing because the goal of such a way that optical signal passing through the fibers is not attenuated or reflected back by the splice. In other word, fusion splicing will have less effect in the transmission distance that fiber optic cable can support. Here are some tips for fusion splicing that may help you.

1. Clean the fiber
2. Stripping the coating off the two fibers that will be spliced together
3. Cleaning of the stripped fiber
4. Each fiber must be cleaved so that its end-face is perfectly flat and perpendicular to the axis of the fiber
5. Aligning of two end-faces of the fibers. This is normally done by the splicing machine by means of: fixed V-groove, optical core alignment, cladding alignment or local injection and detection of light (LID)
6. The two fibers are fused together
7. Check mechanical strength of the splice (normally done by the splicing machine)
8. The bare fiber area around the splice is protected with a splice protector and use the same batch of high quality bare fiber on a route
9. Choose installers who have adequate training and rich experience in fiber connection

As noted above, the optical transmission distance is affected by a variety of factors, like fiber optic cable type, light source of transceiver, and splices and connectors. Frequency of transmission and bandwidth should also be considered to minimum the limitations on the transmission distance. I hope all the suggestions that I have provided above can help you to achieve long transmission distance. Fiberstore offers a variety of high-quality fiber optic cable and optical transceiver modules (like the popular 40G QSFP) that are fully tested. Meanwhile, components like repeater and optical amplifiers are also useful to support the long distance transmission. If you have any interest in our products, please contact us directly.

Reference:
http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/white_paper_c11-463677.pdf

Design Consideration for 40G Ethernet Network

With the speed in the data center now increases from 10G to 40G, different optical technology and cabling are required. But at first we should figure out the design of 40G Ethernet network. There are several key factors that may affect the transition to 40G. This article today will pay special attention to those aspects that influence data center design consideration.

General Data Center Design
The principal goals in data center design are flexibility and scalability, which involve site location, building selection, floor layout, electrical system design, mechanical design and modularity. Furthermore the key to a successful data center facility: one that is sustainable in the long term; the other is to consider it as a receptacle for equipment and operations, as well as an integrated system, in which each component must be considered to be flexible and scalable. Figure 1 shows a typical data center infrastructure design utilizing preterminated optical solutions.

What Does MPO Connector Means for 40G Data Center?
While speeds have increased to 40G, optical connectivity has remained in a duplex format, whether SC or LC. With the advent of 40G/100G Ethernet, multi-fiber push-on (MPO) connector technology are now used at the electronics interface and further into the data center infrastructure design. MPO technology has displayed proven value in cassette-based data center physical layer installations.

The MPO is defined by TIA-604-5-C, Fiber Optic Connector Intermateability Standard. Type MPO (FOCIS-5) as an array connector that can support up to 72 optical fiber connections in a single connection and ferrule. While the MPO is versatile in the fiber count supported, the 12-fiber MPO is the version widely deployed. Many data center designs today use cassette-based duplex LC connectivity or MPO to duplex LC harnesses at the electronics interface, while 12-fiber MPO-based connectivity is used to connect the trunk cabling to each cassette or harness.

40G Standard Provision
The Habtoor STFA Soil Group (HSSG) has designated 40G to support high-performance computing clusters, blade servers, SANs and network-attached storage. For 40G deployment, the QSFP transceiver will utilize a 12-fiber MPO. Deployment of 40G over multi-mode fiber will be achieved with 4-Tx and 4-Rx fibers from the 12-fiber MPO (see in Figure 2). Each of these four “channels” will transmit 10G for the combined 40G transmission. Single-mode fiber transmission will remain duplex connectivity using course wavelength division multiplexing. The HSSG has also defined the transmission media for 40G to include:

• 40GBASE-SR4 (parallel optics)

100m on OM3/125m on OM4—10G on four fibers per direction

• 40GBASE-LR4(cWDM)

10km on single-mode fiber—4x10G 1300nm wavelength region

• 40GBASE-CR4

7m over copper—4x10G (twinax copper)

• 40GBASE-FR(Serial)

2km on single-mode—4x10G 1550nm

As noted above, the QSFP+ module is specified for use with different standard. The 40GBASE-SR4 is terminated with the MPO connector. For example, Cisco QSFP-40G-SR4 QSFP+ transceiver enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber female connectors.

For 12-fiber MPO cassette-based optical systems already installed, 40G migration is as simple as removing the existing cassette from the patch panel housings at the equipment and cross connects and replacing the cassette with an MPO adapter panel. Next, an appropriate 12-fiber MPO jumper would be used to cross-connect the trunk cabling as well as interconnect into the QSFP. Though not widely available currently, future preterminated system trunks may utilize 24-fiber MPO connections, both on the trunks and on the cassette. In this case, 40G deployment would require an interconnect harness terminated with two 12-fiber MPO connectors at the QSFP end, and one 24-fiber MPO at the trunk end. This would provide the needed interface with the 24-fiber MPO-based trunk and the 40G QSFP. A 24-fiber MPO jumper would be needed at the system cross connects to ensure polarity was maintained and that skew was within requirements.

Conclusion
The data center infrastructure must be reliable, manageable, flexible and scalable no matter who you are asking for requirements of data center design. It is the responsibility of the network designers to insure best compatibility of data center. As migrating to 40G, we have 40G QSFP and cables within MPO connectivity. Fiberstore supplies a variety of 40G QSFP modules and cables for you to choose from. Besides QSFP-40G-SR4, QSFP-40G-SR4-S and Cisco QSFP-40G-CSR4 are also available. If you are interested in our products, please contact us directly.

Mellanox Quad Small Form-Factor Pluggable Plus (QSFP+) Interconnect Solutions

From 3Mbps to the IEEE 802.3ba standard now supporting 40/100G speed, telecommunication field has gone through a huge migration. Let us ignore what has happened in this process, and take a look at the sudden emergence of 40G network, which has far-reaching significance to the user. From the equipment point of view, high-density 40GbE core switch board is the general trend, especially in the field of data center switches. 40G products have currently been mass produced. Many major vendors like Cisco, HP, Juniper and Mellanox have released a large variety of 40G devices including 40G transceiver and 40G cables. Of which Mellanox QSFP+ will be introduced in this article in detail.

Mellanox QSFP+
The Mellanox QSFP+ are part of the end-to-end solution that Mellanox offers, allowing you to create the optimal system using the Mellanox Silicon IC device and building the best planned data centers with Mellanox Cables and Modules and Mellanox systems and Adapters. The QSFP interfaces networking hardware to a fiber optic cable or active or passive electrical copper connection, allowing data rates from 4×10 Gbit/s. In addition to meeting or exceeding InfiniBand Trade Association (IBTA) and IEEE standards, Mellanox certified modules are well tested on Mellanox equipment to ensure optimal signal integrity and the best end-to-end performance. The following part will describe three types of Mellanox QSFP+ modules.

• Mellanox QSFP SR4 module uses MTP/MPO connector type to connect an OM3/OM4 fiber cable.
• Mellanox QSFP SR4E module uses MPO connector type to connect OM3 and OM4 fiber cables.
• Mellanox QSFP LR4 module uses LC-LC connector type to connect a fiber cable.

MC2210411-SR4
MC2210411-SR4 (see in Figure 1) is Compatible Mellanox 40GBASE-SR4 QSFP+ transceiver over multi-mode fiber (OM3/OM4) with monitoring (DDM/DOM). It can support up to 100 m operating at 850 nm. It is the standard MSA multi-mode transceiver for 10Gigabit Ethernet and 40Gigabit Ethernet with MPO connector.

MC2210511-LR4
This 40 Gigabit LR4 QSFP+ transceiver (see in Figure 2) is compatible to Mellanox MC2210511-LR4. It operates on single-mode fiber with a link length of up to 10km with monitoring (DDM/DOM), which is standard MSA single-mode transceiver for 10Gigabit Ethernet and 40Gigabit Ethernet with LC connector.

QSFP+ transceivers are designed to carry Serial Attached SCSI, 40G Ethernet, QDR (40G) and FDR (56G) Infiniband, and other communications standards. QSFP modules increase the port-density by 3x-4x compared to SFP+ modules. Mellanox’s QSFP+ optical transceiver is designed to provide outstanding performance in high bandwidth applications such as FDR InfiniBand and Ethernet, at speeds up to 56Gb/s and reaches up to 30 meters. Each of Mellanox’s 56Gb/s QSFP modules contain four fiber optic transceivers, each operating at data rates of up to 14.0625Gb/s. Rigorous production testing ensures the best out-of-the-box installation experience, performance and durability.

Why Choose Compatible Mellanox QSFP+?
In Fiberstore, innovation never stops. And in order to ensure the compatibility and interoperability of each optics from Fiberstore, a test center has been built with professionally trained staff, advanced test facilities and comprehensive original-brand switches. Our mature, field-proven products enable users to benefit from a far more scalable, lower latency, and virtualized fabric with lower overall fabric costs and power consumption, greater efficiencies, and simplified management providing the best return-oninvestment.

Summary
40G products will become the dominant devices of telecom field in the near future. With Fiberstore you have discovered the most trusted source for purchasing new and refurbished equipment. We are committed to provide wide compatible, cost-effective solutions to users. All equipment including Compatible Mellanox QSFP+ modules is guaranteed quality, ready to deploy and backed by warranty. For more detailed information, please contact us directly.

The 40G QSFP transceiver Comparison

Data center regularly went through great migration from 1G, 10G to 40G, 100G over the past few decade. Since IEEE 802.3ba standard defined the 40G Ethernet on June 17, 2010. The newest widely adopted optical transceivers is the QSFP+ that offers aggregated optical speeds of 40G. There are many variants for QSFP+ small from factor including LR4 (10km single-mode), IR4 (2km single-mode) or ESR4 and SR4 for short haul multi-mode. So what are they and what is the difference between them? The following passage will provide a satisfying answer to you.

QSFP optical transceivers have four separate 10G channels to simultaneously operating for supplying 40GbE network and sum up the capacity into a single channel. The following tables shows QSFP40G portfolio, of which 40GBASE-SR4, 40GBASE-LR4 and 40GBASE-ER4 are the most commonly used 40G physical layers.

1. 40GBASE-SR4
40GBASE-SR4 (short range) is a port type for multi-mode fiber and uses 850nm lasers. It uses four lanes of multi-mode fiber delivering serialized data at a rate of 10.3125 Gbit/s per lane. 40GBASE-SR4 has a reach of 100m on OM3 and 150m on OM4. There is a longer range variant 40GBASE-ESR4 with a reach of 300m on OM3 and 400m on OM4. This extended reach is equivalent to the reach of 10GBASE-SR. Take JG325A (see in Figure 2) as an example, it is HP compatible 40GBASE-SR4 QSFP+ transceiver. It primarily enables high-bandwidth 40G optical links terminated with MPO multi-fiber connectors and can also be used in a 4x10G module for interoperability with 10GBASE-SR interfaces.

2. 40GBASE-ER4
40GBASE-ER4 (extended range) is a port type for single-mode fiber being defined in P802.3bm and uses 1300nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength.

3. 40GBASE-LR4
40GBASE-LR4 (long range) is a port type for single-mode fiber and uses 1300nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength. Take FTL4C1QE1C as an example, it is Finisar FTL4C1QE1C  (see in Figure 3) compatible 40GBASE-LR4 QSFP+ transceiver supporting link lengths of 10km at a wavelength of 1310nm.

Comparison of These Three 40GBASE Standards
Through the above definitions of each type of 40G physical layers, you may have a further understanding of them. Now, we are comparing them one by one. 40GBASE-SR4 is for multi-mode fiber while 40GBASE-LR4 and 40GBASE-ER4 is a port type for single-mode fiber. The multi-mode solutions require special MPO fiber ribbons (multi-strand optical cables) to transport the 4 different 10G optical connections. Single-mode solutions use only two strands of fiber and combine the 4 channels using inexpensive CWDM technology. This gives a tremendous advantage, simplifying the connectivity to standard LC optical connectors and thus reducing costs further.

In addition, 40GBASE-LR4 QSFP+ transceivers are most commonly deployed between data-center or IXP sites with single mode fiber. 40GBASE-SR4 QSFP+ transceivers are used in data centers to interconnect two Ethernet switches with 12 lane ribbon OM3/OM4 cables. And from the above figure, we can know that they support different transmission distance in different wavelengths and with different connectors.

Summary
To sum up, 40GBASE-SR4, 40GBASE-LR4 and 40GBASE-ER4 are distinguished with each other in several different features—wavelength, connector, transmission distance, etc. Fiberstore offers a wide variety of high-density and low-power 40GBASE QSFP+ transceiver modules. They are the best-selling products of our company for its large stocks, competitive price and high quality. In addition, there are also a promotion for MTP cables. For more information, please contact us directly.

Reference:
http://www.ieee802.org/3/100GNGOPTX/public/mar12/plenary/cole_01b_0312_NG100GOPTX.pdf