40G QSFP+: Data Center Bandwidth Provider

by http://www.fiber-mart.com

With time passing by, the world’s data centers witness the rapid flowing of digital information whose volume grows at an ever increasing rate. The increase of server virtualization and cloud computing applications, coupled with the trend toward network convergence, all these are boosting today’s data center networks to become faster and more efficient than ever before. Date back to the past years, 100Mbps Ethernet is replaced by 1Gbps Ethernet which is then substituted by 10Gbps Ethernet. With 40GbE and 100GbE being available in the market, some companies or organizations can implement cut-through switching and flatter network architectures which can deliver more bandwidth, so as to reduce traffic latency and meet wireless computing needs.
To ensure the smooth 40GbE networking performance, one device is fundamental—40G QSFP+ (Quad Small Form-factor Plable Plus) transceiver. This QSFP+ transceiver interfaces a network device motherboard (for a switch, router, media converter or similar device) to a fiber optic cable, providing sufficient bandwidth to enable fully non-blocking switch fabrics.
40G QSFP+ Working Principlerinciple
40G QSFP+ transceiver is a hot-swappable module, integrating 4 independent 10Gbps data lanes in each direction for 40Gbps aggregated bandwidth. QSFP+ modules offer customers a wide variety of high-density 40Gbps connectivity options for data center, high-performance computing networks, enterprise core and distribution layers, and service provider transport applications. The release of the IEEE 802.3ba physical layer standard for 40G QSFP+ in 2010 specifies both fiber and copper cabling solutions, such as 40GBASE-SR4, 40GBASE-LR4 and 40GBASE-CR4.
40G QSFP+ Port types
Commonly used QSFP+ transceiver port types are 40GBASE-SR4 and 40GBASE-LR4.
40GBASE-SR4 physical medium dependent (PMD) variant defines a 4 lane parallel optical interconnect for operation up to 100m link length over OM3 multi-mode fiber (MMF) and to 150m over OM4 MMF. It establishes high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multi-fiber female connectors. Four of the twelve fiber for receive, other four for transmit, leaving the middle four fiber unused. Each of the four lanes operates at a data rate of 10.3125Gbps which is the same serial bit rate that was defined for 10Gb Ethernet links in the IEEE 802.3ae standard ratified in 2002.
40GBASE-SR4 PMD addresses the modern need for 40Gbps interconnects in the data center and takes advantage of lower cost 850nm Vertical Cavity Surface Emitting Laser (VCSEL) technology that is widely deployed throughout networking industries. As each of the 4 lanes in 40GBASE-SR4 operates at the same serial bit rate as a 10Gb Ethernet link, there is an opportunity for switching hardware vendors to utilize 40GBASE-SR4 as 4 separate 10Gb Ethernet interconnects. The problem is that 40GBASE-SR4 standard is not defined to be backward compatible with the existing 10GbE short reach interconnect standard.
To address this issue, QSFP BiDi transceivers have been released into the market. A QSFP BiDi transceiver (e.g. Cisco QSFP-40G-SR-BD) transmits full-duplex 40-Gbps traffic over one dual-fiber LC-connector OM3 or OM4 MMF cable. It provides the capability to reuse 10-Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40-Gbps connectivity without making any changes to the previous 10-Gbps fiber cable plant.
40GBASE-LR4 has two link options: coarse wavelength division multiplexing (CWDM) and parallel single-mode fiber (PSM). This passage mainly talks about the first one option.
40GBASE-LR4 CWDM QSFP+ uses a duplex LC connector as the optical interface, able to support transmission distance up to 10km over single-mode fiber (SMF). It converts 4 inputs channels of 10G electrical data to 4 CWDM optical signals by a driven 4-wavelength distributed feedback (DFB) laser array, and then multiplexes them into a single channel for 40G optical transmission, propagating out of the transmitter module from the SMF. Reversely, the receiver module accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths. The central wavelengths of the 4 CWDM channels are 1271, 1291, 1311 and 1331 nm as members of the CWDM wavelength grid defined in ITU-T G694.2. Each wavelength channel is collected by a discrete photo diode and output as electric data after being amplified by a transimpedance amplifier (TIA).
Cable Types for 40G QSFP+
IEEE has specified standards for 40G transmission in both long distance and short distance, which are 40GBASE-SR4 and 40GBASE-LR4. As what has been mentioned above, the latter is sested for 40G transmission over SMF in long distance up to 10km, while the former is for 40G transmission in short distance over MMF (often in with a 12-fiber MPO connector version)—OM3 (up to 100 meters) and OM4 (up to 150 meters). OM3 and OM4, which are usually aqua-colored, are accepted economic solutions for 40G in short distance with lower insertion loss and higher bandwidth. Besides, DACs are also chosen as the 40G cabling solutions sometimes, available in QSFP+ to QSFP+ DAC and QSFP to SFP+ cable versions.
40G QSFP+ transceivers support 40GBASE Ethernet, allowing flexibility of interface choice and great bandwidth for data centers. For your smooth 40GbE performance, fiber-mart supplies various cost-effective QSFP+ transceivers which are fully compatible with major brands, such as Cisco, Juniper, Brocade, and so on. Besides these 40G modules, SFP transceivers are also offered, like Cisco GLC-T, a Cisco compatible 1000BASE-T SFP. All these products are rigorously checked for quality and compatibility assurance. If you want such a module for your networking use, you can consider fiber-mart.

100G Direct and Breakout Cabling Solutions

With the emerging high-speed network standards and rapidly advancing technology, fiber optic network is driven to meet the growing demand for faster access to larger volumes of data. Although 10G/40G Ethernet becomes the mainstream of telecommunication market nowadays, organizations of all sizes still need to be prepared to integrate speeds of 100G and beyond. For data center networking, users can choose different solutions based on the different transmission distance need. In general, there are two kinds of 100G fiber optic solutions: direct cabling and breakout cabling. It is essential for users to understand the detailed information of each type of solution in order to select the one that meets their current and future connectivity needs.
How 100G Optics Develop
After the IEEE completing the certification of the first 100G standard for Ethernet networks, the transceiver industry launched a new type of form factors for 100G connectivity—CFP (“C” for 100, and FP for Form factor Pluggable). Compared to the most popular 40G QSFP, the size of CFP transceiver is huge. And most CFP implementations doubled the power consumption per bit. Furthermore, the price per bit increased by a factor of ten. These disadvantages becomes the main obstacles of the popularity of 100G CFP transceivers.
The next version of 100G form factors is the CFP2, CFP4, and the CPAK that are improved upon the CFP. But when compared to the popular 10G SFP+ and 40G QSFP+, none of these new members of the CFP family improved density, power consumption, or cost. Fugure 1 shows the size comparison between CFP2, CFP4 and QSFP28 modules.
Then here came the 100G QSFP28. The QSFP28 is the exact same footprint as the 40G QSFP+. The 100G QSFP28 is implemented with four 25-Gbps lanes, Just as the 40G QSFP+ is implemented using four 10-Gbps lanes. In all QSFP versions, both the electrical lanes and the optical lanes operate at the same speed, eliminating the costly gearbox found in CFP, CFP2, and the CPAK. The 100G QSFP28 makes it as easy to deploy 100G networks as 10G networks. When compared to any of the other alternatives, 100G QSFP28 increases density and decreases power and price per bit. That’s why it is fast becoming the universal data center form factor. The following part will move on to talk about the 100G optic cabling solutions.
100G Direct Cabling Solutions
QSFP28 transceiver utilizes either fiber or copper media to achieve 100GbE communication in each direction. This transceiver has 4 individual 25GbE lanes which can be used together to achieve 100GbE throughput or separately as 4 individual 25GbE connections (using 4 SFP28 modules).
For 100G short-reach direct cabling within 100m, 100GBASE-SR4 QSFP28 optical module and 100G QSFP28 cable are good choice. Just from the table list of fiber-mart.COM 100G optical modules and cables, we know that 100GBASE-SR4 QSFP28 modules can support up to 100 m on OM4 12 fiber multimode MTP cable. And 100G QSFP28 to QSFP28 direct attach copper cable can support up to 5m and 100G QSFP28 to QSFP28 active optical cable can support up to 10m. Figure 2 describes a 100G direct cabling with the use of QSFP28 to QSFP28 DAC and AOC cables.
For 100G long-haul direct cabling, like 10km, both 100GBASE-LR4 QSFP28 optical module and 100GBASE-LR4 CFP4 transceiver can support up to 10km on single-mode LC patch cables. For longer 100G direct cabling above 10km, the 100GBASE-ER4 CFP is the ideal choice as their transmission distances support up to 40 km.
100G Breakout Cabling Solutions
A breakout cable is a multi-strand cable, typically custom-made, which is divided into multiple duplex cables. For instance, a 40G breakout cable has four individual 10G duplex cables totaling eight strands, while a 100G breakout cable has 10 duplex cables and 20 strands. Figure 3 displays a simple 100G connectivity with 100GBASE-SR4 QSFP28 and QSFP28 to 4SFP28 breakout cables.
Between the 100G optical module and 25G optical modules, there always uses the breakout cables connected the two kinds of optical modules, and the common cable solutions are 100G QSFP28 to 4SFP28 Breakout AOC cables or 100G QSFP28 to 4x 25G SFP28 Breakout Direct Attach Passive Copper Cables.
The commonly used 100G breakout cabling solutions is 100G QSFP28 to 4SFP28 DAC. It’s easy to understand how this type of cable function. Just as the QSFP+ breakout cable, the 40GBASE-SR4 QSFP+ optical module at the one end can be connected to 4x10GBASE-SR SFP+ optical modules at the other end.
As IT infrastructures are planning to migrate to 100G data rate, network designers must carefully weigh alternative implementations of such links. With a variety of fibers already deployed, it is important to understand the interoperability of new optics with existing fibers. And for 100G deployment, you are supposed to understand the benefits and challenges of each type of the fiber optic solutions before taking an action. fiber-mart.COM’s 100G FHD series covers a full range of 100G optical transceivers and cables, like CFP, CFP2, CFP4, QSFP28, as well as 100G QSFP28 to QSFP28 DAC, 100G QSFP28 to 4SFP28 DAC. Besides the above products, 100G FHD Fiber Enclosures, 100G FHD MTP Modular Cassettes, 100G 160 Fiber 2U Panels and 100G CFP SR10 Cables are also provided. If you want to know more about our products, please contact us directly.

How to achieve up to 80km transmission with 40G QSFP+?

For data transmission, there is always a need for faster, longer transmission. With data rates growing up from 1G, 10G to 40G, 100G and even 400G, we can say the world is becoming smaller and smaller, and things are changing faster and faster with modern technology. However, with data rates growing up, transmission distance has not been growing as satisfactory as expected. Under 1G transceiver, max transmission distance can reach as far as 160km, and 120km under 10G transceiver. However, under 40G QSFP+ transceiver, the max distance is only 30km using a QSFP+ ER transceiver, which is quite disappointing.
For customers who have a need to transmit longer distance under 40G, where to turn to for help?
The answer is simple: come to fiber-mart, they have a cost-effective solution for you.
fiber-mart developed a QSFP+ Extender to support customer with up to 80km transmission.
This extender is designed and manufactured to fully meet QSFP+ MSA standard with working temperature: 0°~70°C and Power supply 4A, 3.3V. It has 1x QSFP+ port and 4x SFP+ ports. The QSFP+ port can be connected with customer’s QSFP+ ports using a QSFP+ DAC or AOC cable or QSFP+ transceiver. The 4x SFP+ ports are designed to connect with SFP+ ER to achieve up to 40km transmission and connect with SFP+ ZR for up to 80km transmission. This extender has a embedded fun inside for cooling, so the extender won’t get too hot with long-time operation.
A 2-slot 1U chassis as below is usually used together with this QSFP+ extender. One such chassis can hold two fiber-mart QSFP+ extenders. It is recommended to use only fiber-mart’s 1U chassis with this extender, because the dimension of fiber-mart’s 1U chassis is carefully measured to fit for this extender. The extender can also be rack-mounted with the two screws to make your application more tidy and convenient.
Like DAC cables, this extender also has passive design (PN: CVT-OEO-Q/4S0C) and active design (PN: CVT-OEO-Q/4S1C).
The difference between CVT-OEO-Q/4S0C and CVT-OEO-Q/4S1C is, in CVT-OEO-Q/4S1C, we add a CDR (clock data recovery) inside to enable the extender support longer distance with better performance. Whether to choose CVT-OEO-Q/4S0C or CVT-OEO-Q/4S1C is up to the Signal Integrity performance of your connecting switches. If your switch’s SI performance is good enough, CVT-OEO-Q/4S0C is recommended, because the cost is much lower than the CVT-OEO-Q/4S1C.
Special notice when using fiber-mart QSFP+ extenders:
When using with CVT-OEO-Q/4S0C, if connect the extender with your 40G switches using a QSFP+ DAC cable, the maximum length for the QSFP+ DAC cable recommended is 0.5 meter. Longer DAC cables may affect the performance or even lead to link issues. A QSFP+ AOC cable or QSFP+ transceiver is a good choice if you’d like to link up longer. Till now, no issue is found using a AOC cable or transceiver for the 40G link with either the CVT-OEO-Q/4S0C or the CVT-OEO-Q/4S1C.
When using with either CVT-OEO-Q/4S0C or CVT-OEO-Q/4S1C, make sure your switch is configured in 4 x 10G mode instead of 1 x 40G mode. Because both extenders are designed as a breakout 4 x 10G extender.
Both CVT-OEO-Q/4S0C and CVT-OEO-Q/4S1C can be used with both standard SFP+ ZR, and SFP+ CWDM 80km optics to achieve 80km transmission. Power consumption depends on the transceivers inserted instead of the extender.

How to choose 40G QSFP+? AOC, DAC or Transceiver?

40Gbps QSFP+ ports are very popular in IDC. Then, do you know how to choose the most suitable product for your networking infrastructure? It refers to the link length, fiber applied, devices to be connected etc.
For 1~5m link length, 40G QSFP+ DAC is the ideal choice for data center. QSFP+ DAC owns advantages:
Lower Power Consumption: as DAC cables all are passive direct-attach copper cables, no power consumption;
Wider Temperature Range: this is also because it’s passive design;
Lower Cost: could save about 60% or more compared with QSFP+ AOC cable. As data center applied DACs in large quantity, so there will be a large amount to be save;
Faster Transmission: as it is no need to switch between optical to electronic signals.
It is easy to realize the connectivity between two 40G switches or connect one 40G and 10G switches by QSFP+ breakout cables(QSFP-4SFP10G-CU1M).
For 1~100m link length, 40G QSFP+ AOC is preferable for data center. QSFP+ AOC is consist of two QSFP+ transceivers and one 8-core fiber cable, with laser components inside, cable and connector are fixed, which meets the data centers’ usage habit, needless to consider the plug in or plug out of patch cords.
The cables of AOC are thin and AOC has better bend radius than DAC, so if the data centers don’t have enough space for cabling, AOC is a good choice.
Also because the AOC cable is thin and space-saved, the switches will have more room for air flow and easy for cooling system.
AOC always has a good eye pattern, and its performance is very good. It can meet up to 100m on OM3 MMF or up to 150m on OM4 MMF.
Once it’s short distance connection of 1m~150m, you could adopt 40G QSFP+ SR4 optic. It offers 4 independent signal channels each capable of 10Gbps, over 100 meters on OM3 or over 150 meters on OM4.
As a transceiver, it always supports DD function. Enterprise network always uses this solution.
When the link length is less than 300m, 40G QSFP+ eSR4 module is suggested to use. QSFP+ eSR4 supports link lengths of up to 300 meters and 400 meters on laser-optimized OM3 and OM4 MMF respectively.
If your link length is long about 2km, please use 40G QSFP+ IR4 transceiver. 40G QSFP+ IR4 module supports link lengths of up to 2 kilometers over a standard pair of G.652 single-mode fiber (SMF) with duplex LC connectors.
For long distance connection of 10km, the 40GBASE-LR4 QSFP module supports link lengths of up to 10 kilometers over a standard pair of G.652 single-mode fiber with duplex LC connectors. The 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device. This is applied when you connect two 40Gb devices.
If you would like to connect a 40G switch and a 10G switch away from each other 10km, 40G QSFP+ LR4 PSM module is the solution, which is available to link with 4x 10G devices on MPO to 8LC patch cord cables(SMF), as solution picture below.
40G QSFP+ LX4 transceiver is a hot star, as it can work with MMF or SMF. It’s role has been a very good play especially when used in lines that do not know what cable used. When QSFP+ LX4 module works with OM3, it supports up to 150m on OM3. When QSFP+ LX4 module connects with SMF, it supports up to 2km.
Finally, which brand should we choose for the 40G QSFP+ AOC, DAC and transceivers? Cisco, H3C, Juniper etc. are the most common brands, however products of these brands can only be applied in the corresponding switches. And the price of original pieces are super high, that caused there are renewed, recycled and even fake products in market. Here I recommend you two companies: Finisar and fiber-mart, which are the leading optical communication products manufacturers. fiber-mart‘s products can be coded according to the switch model. They can satisfy most of the switches in the current market.

How to choose the basic 40G QSFP + optical components ?

With high-speed development of the optical communication industry,why is the third-party 40G QSFP with good compatibility and high stability the perfect choice for customers?

With high-speed development of the optical communication industry,why is the third-party 40G QSFP with good compatibility and high stability the perfect choice for customers?


40G LR4 QSFP+ Transceiver

Conforming to the 802.3ba (40GBASE-LR4) standard, the 40G LR4 QSFP+ transceiver together with the LC connector can support an optical link length up to 10 kilometers over single mode fiber. 40G LR4 QSFP+ transceivers offer 4 independent transmit and receive channels. And to realize the function of transmitting the 4-channel signals over the single mode fiber, this kind of transceiver has to introduce MUX/DEMUX to multiplex/de-multiplex optical signals.the working principle of this kind of QSFP+ transceiver is : In the transmit side, four 10 Gbp/s serial data streams are passed to laser drivers. The laser drivers control directly modulated lasers (DMLs) with wavelengths. the output of the four DMLs are optically multiplexed to a single-mode fiber through an industry-standard LC connector. In the receive side, the four 10 Gbp/s optical data streams are optically de-multiplexed by the integrated optical demultiplexer; then, each data steam is recovered by a PIN photodetector/transimpedance amplifier and passed to an output driver. The following figure shows the functional block diagram of the 40G LR4 QSFP+ transceiver.


40G SR4 QSFP+ Transceiver

40GBASE-SR4 QSFP+, Short-reach (SR) transceivers for 40G connectivity in a QSFP form factor, uses independent transmitter and receiver sections, each with 4 parallel fiber strands. It can transmit 150 meters over OM4 MMF. For a 40G connection, 8 fiber strands are required, and 12-fiber MPO connectors are used. Consequently, 4 fiber strands in each connection are wasted .For most data center networks, the aggregation-layer fiber infrastructure is built for 10G connectivity. That either supports direct connections between devices over LC-to-LC MMF, or uses LC-to-LC fibers to attach devices to patch panels. Regular duplex LC-to-LC fibers cannot be directly reused for 40G connectivity using traditional 40G transceivers.The operating principle of the 40G SR4 QSFP+ Transceiver is : the transmitter converts parallel electrical input signals into parallel optical signals through the use of a laser array. Then the parallel optical signals are transmitted parallelly through the multimode fiber ribbon. Reversely, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals. The following figure shows the functional block diagram of the 40G SR4 QSFP+ Transceiver.


Features of OEM 40G QSFP Transceiver Modules

As we know, the OEM 40G QSFP transceiver from name brand like Cisco, Juniper and Brocade is widely used in data center and enterprise network. They all have some great features. The Cisco 40G QSFP transceiver offers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options for data center, high-performance computing networks, enterprise core and distribution layers, and service provider applications. Here are some benefits of Cisco 40 Gbps transceiver:

  • Hot-swappable input/output device that plugs into a 40 Gigabit Ethernet Cisco QSFP port
  • Flexibility of interface choice (for different reach requirements and fiber types)
  • Interoperable with other IEEE-compliant 40GBASE interfaces where applicable
  • Certified and tested on Cisco QSFP 40G ports for superior performance, quality, and reliability
  • High-speed electrical interface compliant to IEEE 802.3ba
  • QSFP Form factor, 2-wire I2C communication interface and other low-speed electrical interface compliant to SFF 8436 and QSFP
  • The Brocade 40 Gbps transceiver supports highly reliable operations in data center and is optimized for Brocade switching platforms. It undergoes strict qualification and certification testing.


For the 40 Gbps transceiver, Fiber-MART provides high quality QSFP+ transceivers and various of compatible brands for you, Cisco, Genetic, Juniper Networks, Arista Networks, Brocode, HPE, Dell, Intel, IBM, etc. All have passed the compatibility testing. and the prices are much lower than other vendors,if you any question pls feel free to contact me .E-mail :service@fiber-mart.com

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