56G QSFP+ DAC Vs. 40G QSFP+ DAC

High speed data transmission is the prerequisite for enterprise network deployment. For big data centers, 40G is still the mainstream. For 40G network, 40 gbps transceiver and 40gb ethernet cable are important components, and they can be classified according to transmission distance. For long transmission distance, there are 40G LR4 QSFP+ transceiver and singlemode fiber cable; for short transmission distance, there are 40G SR4 QSFP+ transmission and multimode fiber cable. In addition, for 40G short link, there is QSFP+ DAC cable. Two types of QSFP+ DAC cables are available on the market: 56G QSFP+ DAC vs. 40G QSFP+ DAC, what’s the difference between them? This article will make a comparison.

56G QSFP+ DAC Vs. 40G QSFP+ DAC: Same construction

We know that DAC cable is a kind of high speed passive copper cable with one connector on each end. The connectors are not real optical transceiver modules but in the form of optical transceiver module. DAC twinax cable Therefore, QSFP+ DAC consists of two QSFP+ transceiver style connectors and one twinax copper cable. With the same construction, the operation of 56G QSFP+ DAC and 40G QSFP+ DAC in 40G network deployment is the same, too. Just plug the connector into 40G QSFP+ port on the switch on both sides, and then you can get 40G link. Here is a figure of QSFP+ DAC cable for you.

QSFP DAC

56G QSFP+ DAC Vs. 40G QSFP+ DAC: Different protocols

As qsfp+ passive copper cable, both 56G QSFP+ DAC and 40G QSFP+ DAC are QSFP MSA compliant. But 40G QSFP+ DAC supports 40G InfiniBand 8x DDR, 4x QDR, 10G/40Gigabit Ethernet, Fibre Channel, while 56G QSFP+ DAC supports 40G InfiniBand 4x FDR, 56Gigabit Ethernet, Fibre Channel. What’s the different between InfiniBand DDR, QDR and FDR? InfiniBand (abbreviated IB) is a computer-networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also used as either a direct or switched interconnect between servers and storage systems, as well as an interconnect between storage systems. And the following figure shows InfiniBand specification. We know that QSFP+ DAC cable uses four channels for data transmission. And for 40G QSFP+ DAC, it supports 40G InfiniBand 8x DDR, 4x QDR, so each channel can achieve 10G data rate; for 56G QSFP+ DAC, it supports 40G InfiniBand 4x FDR, so the maximum data rate of each channel is 14G.

InfiniBand Specification

Conclusion

Characterized by low Insertion loss and power consumption, qsfp+ passive copper cable is a cost-effective option for 40G data transmission over short distance. As for 56G QSFP+ DAC vs. 40G QSFP+ DAC, the only different is that the former can operate high bandwidth than the latter one. Therefore, if your network needs 40G data transmission, then 40G QSFP+ DAC cable; if you need more than 40G bandwidth, then choose 56G QSFP+ DAC.

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A Closer Look at 40G QSFP+ SR4 Transceiver

As 40G network has been widely applied in today’s data center cabling system, 40G QSFP+ transceivers gain great popularity among data center managers. And for short data transmission distance, 40G QSFP+ SR4 transceiver is preferred. This article is going to focus on 40G QSFP+ SR4 transceiver and share several cabling solutions for 40G QSFP+ SR4 with you.

Overview of 40G QSFP+ SR4 Transceiver

40G QSFP+ SR4 transceiver is a parallel fiber optic transceiver which means it uses four fibers for transmitting and four fibers for receiving at the same time. Designed with MTP/MPO interface, 40G QSFP+ SR4 transceiver is used together with multimode fiber, such as OM3 and OM4. Working on wavelength of 850 nm, 40G QSFP+ SR4 transceiver can support 40G fiber optic transmission with the link length up to 100 meters over OM3 fiber and 150 meters over OM4 fiber. For application, 40G QSFP+ SR4 transceiver can be used for 10G to 40G and 40G to 40G connections. Here is a figure of 40G QSFP+ SR4 transceiver for you.

40G QSFP+ SR4 transceiver

10G to 40G Connection

Since 40G QSFP+ SR4 transceiver uses four independent full-duplex transmit and receiver channels, the 40G optical signal can be split into four 10G optic signals. Therefore, we can increase the fiber count at the 10G distribution end to realize 10G to 40G connection. As the following figure shows, we can use 12f MPO trunk cable and fiber enclosure. Four 10G SFP+ SR transceivers are inserted into 10G ports on one side, while one 40G QSFP+ SR4 transceiver is inserted into 40G port on the other side. Then the four 10G SFP+ SR transceivers are connected with four duplex LC patch cables which are plugged into LC ports on the front side of MPO fiber cassette inside the fiber enclosure, and the 40G QSFP+ SR4 transceiver is connected with 12f MPO trunk cable which is plugged into MTP/MPO port on the rear of MPO fiber cassette. Finally, the whole optical link is completed.

40G QSFP+ SR4 transceiver for 10G to 40G connectionA

We can also use MPO to LC fanout and MTP fiber patch enclosure which includes MTP fiber adapter panels. This cabling solution is similar to the previous one, but the difference is that the four 10G SFP+ SR transceivers are connected with MPO to LC fanout which is plugged into MTP/MPO port on the MTP fiber patch enclosure. The scenario is shown in the following figure.

40G QSFP+ SR4 transceiver for 10G to 40G connectionB

40G to 40G Connection

The following figure shows the simplest scenario for 40G to 40G connection. Two 40G QSFP+ SR4 transceivers are separately inserted into two 40G switches. Then the two 40G QSFP+ SR4 transceivers are connected by 12f MPO trunk cable.

40G QSFP+ SR4 transceiver for 40G to 40G connectionA

We can also use MTP fiber patch enclosure to achieve better cable management and higher density cabling. The scenario is shown in the following figure. With the use of MTP fiber enclosure, cable management for 40G to 40G connection could be easier. A 48-port 1U rack mount MTP fiber patch enclosure includes up to four 12-port MTP fiber adapter panels with MPO MTP fiber optical adapters on it, here is a figure for you.

40G QSFP+ SR4 transceiver for 40G to 40G connectionB

Conclusion

Designed with parallel transmission mode, 40G QSFP+ SR4 transceiver has a wide range of cabling applications with great flexibility. The cabling solutions mentioned above are just several commonly used ones. As for detailed cabling solutions for 40QSFP+ SR4 transceiver, it is suggested to depend on the practical applications and cabling environments. I hope after reading this article, you can learn more about 40G QSFP+ SR4 transceiver.

Can 40GBASE-LR4 Be Used for 4x10G?

We know that 40GBASE-SR4 QSFP+ transceiver can be used for 4x10G SFP+ connections, because it offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G over 100 meters of OM3 MMF or 150 meters of OM4 MMF. However, for 40GBASE-LR4 QSFP+ transceiver, it is commonly utilized over long transmission distance of SMF in 40G network applications. Can 40GBASE-LR4 be used for 4x10G? The answer depends and this article will focus on this question.

40GBASE-LR4 CWDM QSFP+ Transceiver Cannot Be Used for 4x10G

The 40GBASE-LR4 CWDM QSFP+ transceiver, such as QSFP-40GE-LR4, is compliant to 40GBASE-LR4 of the IEEE P802.3ba standard. It contains a duplex LC connector for the optical interface. The maximum transmission distance of the transceiver is 10km over SMF. In the transmit side, the transceiver 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 side accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths. Each wavelength channel is collected by a discrete photo diode and output as electric data after being amplified by a transimpedance amplifier (TIA). Therefore, 40GBASE-LR4 CWDM QSFP+ transceiver cannot be used for 4x10G. It cannot be split into 4x10G, because it uses 4 wavelengths on a pair of single-mode fiber with LC duplex connector, and does not allow itself to split into 4 pairs without substantial complexity to split out the wavelengths.

Working Principle of 40GBASE-LR4 CWDM QSFP+ Transceiver

40GBASE-LR4 PSM QSFP+ Transceiver Can Be Used for 4x10G

The 40GBASE-LR4 PSM QSFP+ transceiver is a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It also offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G on 10km of single-mode fiber. The transmitter side accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver side converts parallel optical input signals via a photo detector array into parallel electrical output signals. That’s to say, the parallel optical signals are transmitted parallelly through 8 single mode fibers. As a result, 40GBASE-LR4 PSM QSFP+ transceiver can be used for 4x10G, because it uses parallel (ribbon) fiber with MTP/MPO connector, which allows the creation of 4 fiber pairs.

Working Principle of 40GBASE-LR4 PSM QSFP+ Transceiver

Note: From an optical transceiver module structure viewpoint, PSM uses a single uncooled CW laser which splits its output power into four integrated silicon modulators. Therefore, it allows for splitting into 4x10G (single-mode).

Conclusion

In a world, the answer of question “Can 40GBASE-LR4 be used for 4x10G?” depends. The 40GBASE-LR4 CWDM QSFP+ transceiver cannot be split into 4x10G, while for 40GBASE-LR4 PSM QSFP+ transceiver, it cab be used for 4x10G. To put it simply, 40G QSFP+ transceiver which is with MTP/MPO interface can be used for 4x10G connections, otherwise, it can only support 40G link.

Originally published at http://www.china-cable-suppliers.com/can-40gbase-lr4-used-4x10g.html

Three Types of 40G QSFP+ Transceivers for Long Distance Transmission

Nowadays, people have access to data at all times and at everywhere, which gives rise to the rapid development of big data technology. During the application of big data technology, transceiver has become an indispensable component, which can help executives to get their data in real-time. Recently, 40GbE network has replaced 10G Ethernet network and has been used worldwide. For 40GbE network deployment, high-density cabling is the basic requirement. Also, optical components for high-speed data transmission are necessary. This article aims to introduce three types of 40G QSFP+ transceivers for long distance transmission—QSFP-4X10GE-IR, QSFP-40G-PLRL4 and QSFP-4X10G-LR-S.

40G QSFP+ transceiver

QSFP-4X10GE-IR Transceiver

Designed with MTP interface, the parallel QSFP-4X10GE-IR transceiver offers 4 independent transmit and receive channels, each capable of 10Gbps operation. It utilizes 12-ribbon single-mode fiber cable with female MTP/MPO connector to realize 40Gbps data link with transmission distances up to 1 km.

QSFP-40G-PLRL4 Transceiver

The QSFP-40G-PLRL4 transceiver uses 12-fiber MTP interface to achieve 40Gbps parallel transmission, supporting maximum data link lengths up to 1.4 km. The cable type required for QSFP-40G-PLRL4 transceiver is an APC (angle polished connector) single-mode 12-fiber MTP cable. APC is the only available type for single-mode MTP-12 fiber.

QSFP-4X10G-LR-S Transceiver

The QSFP-4X10G-LR-S transceiver is a parallel 40Gbps QSFP+ optical module. It supports link lengths of up to 10 km on G.652 single-mode fiber. It enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP female connector. It can also be used in a 4x10G mode for interoperability with 10GBASE-LR interfaces up to 10 km.

When reading this, you may find that all these three types of 40G transceivers are designed with MTP interface and use parallel transmission. In parallel transmission, data signals are sent sequentially on the same channel. In addition, they all use 1310nm wavelength and can transfer data signals up to at least 1 km. What’s more, they are compatible with the Small Form Factor Pluggable Multi-Sourcing Agreement (MSA) and they support Digital optical monitoring (DOM).

Working Principle

Because the structures of these three types of 40G transceivers are similar, their working principles are similar, too. The single-mode cable terminated with 12-fiber MTP connector plugged into the 40G transceiver carries the 40G signal over only 8 of the 12 fibers, remaining 4 fibers unused. The 8 used fibers are mapped as 4x10G Tx and Rx pairs. We can easily understand the working principle of these three types of 40G QSFP+ transceivers from the figure below. In the transmit side, 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 single-mode fiber ribbon terminated with MTP/MPO connector. While in the receive side, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.

working principle of 40G QSFP+ transceiver

Application

Many data centers are in the process of 10G to 40G migration. To make migration path smooth, we can use 40G transceivers together with MTP cable. Take QSFP-40G-PLRL4 transceiver for example, we can simply use MTP-LC harness cable to connect one QSFP-40G-PLRL4 transceiver and four 10GBASE-LR SFP+ transceivers. Here is a figure for you to have a better understanding of the connectivity. In addition, for 40 connectivity, we can use MTP trunk cable to connect two QSFP-40G-PLRL4 transceivers to make the optical links. Using 40G QSFP+ transceiver for high-speed long distance transmission over single-mode fiber is a cost-effective solution.

QSFP-40G-PLRL4 transceiver for 10G to 40G connectivity

Conclusion

With special structures, MTP components are popular with data center managers for fast installation, high density and high performance cabling. QSFP-4X10GE-IR, QSFP-40G-PLRL4 and QSFP-4X10G-LR-S these three 40G QSFP+ transceivers have special interface designs which can be compatible with single-mode MTP connector and support long distance transmission. During the deployment of 40G QSFP+ module, selecting proper MTP assemblies are also essential to successfully accomplish the link.

Originally published at http://www.fiber-optic-cable-sale.com/some-thoughts-required-before-mtp-cabling.html

40G QSFP+ – A Cost-effective Transceiver Solution

Data transmission with higher density and bandwidth has become the trend under today’s networking environment. And for better network performance, the existing bandwidth has been generated to 40Gbps. Among various network devices designed for 40 Gigabit Ethernet (GbE) links, 40G QSFP+ transceivers play an important role in driving the bandwidth to a mounting point. This passage is going to focus on this cost-effective transceiver. First, let’s move on to the overview of 40G QSFP+.

Overview of 40G QSFP+ Transceiver

The 40G QSFP+ (Quad Small Form-Factor Pluggable Plus) transceiver is a compact, hot-pluggable, parallel fiber optical transceiver with four independent optical transmit and four receive channels. Each channel is able to transfer data at 10Gbps. Thus, a QSFP+ transceiver with Four high-speed channels can support data rates up to 40Gbps and it supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards. In addition, 40G QSFP+ is primarily used in switches, routers, and data center equipment where it provides higher density than SFP+ transceiver.

Three types of 40G QSFP+ Transceiver

With the development of the SFF-8436 Multi Source Agreement, many vendors are now offering a variety of IEEE- and MSA-compliant QSFP+ devices for fiber networks. And there are three basic 40G QSFP+ transceivers for this standard: 40G LR4 QSFP+ transceiver, 40G SR4 QSFP+ transceiver and 40G LR4 parallel single mode (PSM) transceiver.

40G LR4 QSFP+ Transceiver

The 40G LR4 QSFP+ Transceiver converts 4 inputs channels of 10Gbps electrical data to 4 CWDM optical signals, and multiplexes them into a single channel for 40Gbps optical transmission. Together with duplex LC connectors, 40G LR4 QSFP+ transceiver can support an optical link length up to 10 kilometers over the single mode fiber.

We can easily understand the working principle of 40G LR4 QSFP+ transceiver from the figure below. In the transmit side, four 10Gbps serial data streams at different wavelengths are passed to laser drivers. Then four data streams are optically multiplexed to a single mode fiber through LC connector. In the receive side, four 10Gbps optical data streams are de-multiplexed into four individual data streams by the optical de-multiplexer. And each data stream is collected by a PIN photodiode /TIA array and passed to an output driver.

Working Principle of 40G LR4 QSFP+ Transceiver

40G SR4 QSFP+ Transceiver

The 40G SR4 QSFP+ Transceiver provides a high-bandwidth 40G optical connection over fiber ribbon terminated with MPO/MTP connectors. Unlike the 40G LR4 QSFP+ transceiver, this kind of transceiveris used together with multi-mode fiber, supporting with a link length up to 100 meters on OM3 cable and 150 meters on OM4 cable.

We can easily understand the working principle of 40G SR4 QSFP+ transceiver from the figure below. 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 multi-mode fiber ribbon. Reversely, the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals.

Working Principle of 40G SR4 QSFP+ Transceiver

40G LR4 Parallel Single Mode (PSM) Transceiver

The 40G LR4 PSM transceiver is designed with QSFP+ form factor, optical/electrical connection and digital diagnostic interface according to the QSFP+ MSA. As a highly integrated 4-channel optical module, this kind of transceiver can provide increased port density and total system cost savings. 40G LR4 PSM transceiver supports up to 10 kilometers over single mode fiber through MPO/MTP fiber ribbon connectors.

From the figure below, we can easily understand the working principle of 40G LR4 PSM transceiver which is nearly the same as that of 40G SR4 QSFP+ transceiver. The transmitter converts parallel electrical input signals into parallel optical signals and the receiver converts parallel optical input signals via a photo detector array into parallel electrical output signals. The difference is that the cable used in this link is single mode ribbon fiber cable. That’s to say, the parallel optical signals are transmitted parallelly through 8 single mode fibers.

When reading this, you may have found that both 40G LR4 QSFP+ transceiver and 40G QSFP+ PSM transceiver can support the maximum transmission distance of 10km. The obvious difference between these two transceivers is that the former establishes 40G links over 2 optical SMFs with a duplex LC connector, while the latter achieves 40G links via 8 optical SMFs with a MTP/MPO fiber ribbon connector. And we can easily find that 40G LR4 PSM transceiver costs more than 40G LR4 transceiver which uses only 2 single mode fibers to support an optical link. Besides, in the data center fiber infrastructure, the patch panel has to be changed to accommodate MTP cables, which would cost more than LC connectors and regular SMF cables.

Working Principle of 40G LR4 PSM Transceiver

Conclusion

From the introduction above, 40G SR4 QSFP+ transceiver is suitable for short-distance transmissions. So it is often used in data centers to interconnect two Ethernet switches with 12 lane ribbon OM3/OM4 cables. While 40G LR4 QSFP+ transceiver and 40G LR4 PSM transceiver are often used in long-distance transmission applications. I hope this passage can help you know more about 40G QSFP+ and choose a suitable optical transceiver module according to your need.