Category Archives: QSFP+ Transceiver

40G Deployment: The Cost Difference Between SMF and MMF


40G network are now being extensively adopted within LANs and data centers. 100G is still predominantly in the carrier network, but could soon extend its stretch to your local network. There exists much confusion as to whether to choose single-mode fiber (SMF) or multimode fiber (MMF) for deploying 40G bandwidth, considering the single mode vs multimode fiber cost. As well as how to get fully prepared for scaling to higher-speed 100G. If you are hesitating to make the choice, you may find this article helpful.

40G Cost: Difference Between SMF and MMF

Multimode Fiber (MMF): Cost-effective With Higher Tolerance to Dirt

Cost-effectiveness: Multimode fiber (MMF) has been evolving to handle the escalating speed: OM3 has been superseded by OM4 and OM5 is there ready to use. MMF has a wider array of short distance transceivers that are easier to get. One of the liable argument that in favor of using MMF is that multimode optics use less power than single-mode ones, but only in condition that you have tens of thousands of racks. In essence, MMF still has its position under certain circumstances, like cabling within the same rack, in Fiber Channel and for backbone cabling in some new construction buildings.

smf mmf

Tolerance to Dirt: Multimode fiber tends to have a lot more tolerance to dirty connections than single-mode fiber. It can handle very dirty couples or connectors to ensure reliable and consistent link performance. Besides, it is easy to terminate, and more accommodating bend radius. So MMF is preferred by links that change frequently or are less than permanent.

smf mmf

Single-mode Fiber (SMF): Higher Capability and Better Future-proofing

Speed capability: Capacities are really vital for network growth. SMF does so with relatively larger capability than that of MMF. The gap between SMF and MMF cabling is much wider for high-density, high-speed networks. If you want to go further with SMF, say scaling to 100G or beyond, you simply need to upgrade the optics. Unlike using MMF, in which you have to upgrade the glass (OM3 to OM4 to OM5), the labor cost concerning this cannot be underestimated. The capacity for scaling of SMF alone makes it worth the cost. You can use single-mode for almost everything, no need for media conversion. SMF offers enough bandwidth to last a long time, making it possible to upgrade 100 Gbps to Tbps with CWDM/DWDM.

smf mmf

Future proofing: Despite the fact that SM optical transceivers usually cost higher than MM optics, SMF cabling is cheaper and can support much longer distance and reliable performance. Not to mention that bandwidth on SMF keeps going up and up on the same old glass. The good news is that the cost of SMF is dropping in recent years, and it is redesigning to run with less power, thus advocators of SMF think that it is pretty much the only rational choice for infrastructure cabling and the sure winner for today and tomorrow.

SMF and MMF: A Simple Comparison of Cost

There is no doubt that SMF is a better investment in the long run, but MMF still has a long way to go in data center interconnections. In fact the price difference of SMF optics and MMF optics can be minimized if you choose the right solution. Assuming to connect two 40G devices at 70 m away, let’s see the single mode vs multimode fiber cost for deployment in the following chart.

Module Connector Type SMF or MMF Price 2 Connections 4 Connections 6 Connections
40GBASE-SR4 MPO12 MMF, OM4 $49.00 $564.48 $1128.96 $1693.44
40GBASE-BiDi LC MMF, OM4 $300.00 $1534.24 $2734.24 $3934.24
40GBASE-LR4 LC SMF, OS2 $340.00 $1,609.84 $2,969.84 $4,329.84
80 Gbit 160 Gbit 240 Gbit



Choosing the right fiber for your network application is a critical decision. Understanding your system requirements in order to select the appropriate fiber will maximize the value and performance of your cabling system. Be sure to select the right cable on the basis of aspects including link length, performance, and of course costs. FS provides a broad range of 40G optical transceivers and fiber patch cables with superior quality and fair price. For more details, please visit

Related Article: Single Mode vs Multimode Fiber: What’s the Difference? 

Can I Use the QSFP+ Optics on QSFP28 Port?


100G Ethernet will have a larger share of network equipment market in 2017, according to Infonetics Research. But we can’t neglect the fact that 100G technology and relevant optics are still under development. Users who plan to layout 100G network for long-hual infrastructures usually met some problems. For example, currently, the qsfp28 optics on the market can only support up to 10 km (QSFP28 100GBASE-LR4) with WDM technology, which means you have to buy the extra expensive WDM devices. For applications beyond 10km, QSFP28 optical transceivers cannot reach it. Therefore, users have to use 40G QSFP+ optics on 100G switches. But here comes a problem, can I use the QSFP+ optics on the QSFP28 port of the 100G switch? If this is okay, can I use the QSFP28 modules on the QSFP+ port? This article discusses the feasibility of this solution and provides a foundational guidance of how to configure the 100G switches.

For Most Switches, QSFP+ Can Be Used on QSFP28 Port

As we all know that QSFP28 transceivers have the same form factor as the QSFP optical transceiver. The former has just 4 electrical lanes that can be used as a 4x10GbE, 4x25GbE, while the latter supports 40G ( 4x10G). So from all of this information, a QSFP28 module breaks out into either 4x25G or 4x10G lanes, which depends on the transceiver used. This is the same case with the SFP28 transceivers that accept SFP+ transceivers and run at the lower 10G speed.

QSFP can work on the QSFP28 ports

A 100G QSFP28 port can generally take either a QSFP+ or QSFP28 optics. If the QSFP28 optics support 25G lanes, then it can operate 4x25G breakout, 2x50G breakout or 1x100G (no breakout). The QSFP+ optic supports 10G lanes, so it can run 4x10GE or 1x40GE. If you use the QSFP transceivers in QSFP28 port, keep in mind that you have both single-mode and multimode (SR/LR) optical transceivers and twinax/AOC options that are available.

In all Cases, QSFP28 Optics Cannot Be Used on QSFP+ Port

SFP+ can’t auto-negotiate to support SFP module, similarly QSFP28 modules can not be used on the QSFP port, either. There is the rule about mixing optical transceivers with different speed—it basically comes down to the optic and the port, vice versa. Both ends of the two modules have to match and form factor needs to match as well. Additionally, port speed needs to be equal or greater than the optic used.

How to Configure 100G Switch?

For those who are not familiar with how to do the port configuration, you can have a look at the following part.

  • How do you change 100G QSFP ports to support QSFP+ 40GbE transceivers?

Configure the desired speed as 40G:
(config)# interface Ethernet1/1
(config-if-Et1/1)# speed forced 40gfull

  • How do you change 100G QSFP ports to support 4x10GbE mode using a QSFP+ transceiver?

Configure the desired speed as 10G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 10000full

  • How do you change 100G QSFP ports from 100GbE mode to 4x25G mode?

Configure the desired speed as 25G:
(config)# interface Ethernet1/1 – 4
(config-if-Et1/1-4)# speed forced 25gfull

  • How do you change 100G QSFP ports back to the default mode?

Configure the port to default mode:
(config)# interface Ethernet1/1-4
(config-if-Et1/1)# no speed

Note that if you have no experience in port configuration, it is advisable for you to consult your switch vendor in advance.


To sum up, QSFP+ modules can be used on the QSFP28 ports, but QSFP28 transceivers cannot transmit 100Gbps on the QSFP+ port. When using the QSFP optics on the QSFP28 port, don’t forget to configure your switch (follow the above instructions). To make sure the smooth network transmission, you need to ensure the connectors on both ends are the same and no manufacturer compatibility issue exists.

How to Convert a Port From QSFP+ to SFP+?


As data communications technology migrates from 10GbE to 40GbE and beyond, it is often necessary to connect 40GbE equipment with existing 10GbE equipment. As we know 40GbE NIC or switch usually equipped with QSFP+ ports, and 10GbE switch usually equipped with SFP+ ports. That is to say we must know how to convert a QSFP+ port to a SFP+ port. At present, there exists three ways to solve this problem. I will explain it in this blog.

QSFP+ to SFP+ Cable
As shown in the figure below, a QSFP+ to SFP+ cable consists of a QSFP+ transceiver on one end and four SFP+ transceivers on the other end. The QSFP+ transceiver connects directly into the QSFP+ access port on the switch. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously. The SFP+ links are designed for data rates up to 10 Gbps each. QSFP+ cable is available in passive and active two types. Passive QSFP+ cable has no signal amplification built into the cable assembly, therefore, their transmission distance is usually shorter than an active one.


CVR-QSFP-SFP10G: QSFP+ to SFP+ Adapter (QSA)
You can convert a QSFP+ port to a SFP+ port using the QSFP+ to SFP+ adapter. QSA provides smooth connectivity between devices that use 40G QSFP+ ports and 10G SFP+ ports. Using this adapter, you can effectively use a QSFP+ module to connect to a lower-end switch or server that uses a SFP+ based module. This adapter is very easy to use. As shown in the figure below, just plug one side of the QSA in your QSFP+ port, and plug a SFP+ module into another side of the QSA. Then you can convert a QSFP+ port to a SFP+ port easily.


QSFP+ Breakout Cable
As we know, parallel 40GBASE-SR4 QSFP+ modules use 8 out of 12 MPO/MTP interface fibers transmitting 4 x duplex (DX) channels (4 x transmit and 4 x receive). The QSFP+ breakout cable uses a pinless MTP connector on one end for interfacing with the QSFP port on the switch. The other end contains 4 duplex LC connectors, which provide connectivity to the SFP+ ports on the switch. Thus higher-speed equipment (40G QSFP+) can be connected to slower-speed equipment (10G SFP+) successfully.

QSFP+ Breakout Cable convert qsfp+ to sfp+

When you want to connect a QSFP+ port to a SFP+ port, you can use QSFP+ to SFP+ cable, QSFP+ to SFP+ adapter or QSFP+ breakout cable. All these three options can meet your needs. FS.COM provides a full range of compatible QSFP+ cable, which can be 100% compatible with your Cisco, Juniper, Arista and Brocade switches and routers. Or you want to use QSFP+ breakout cable, you can also find it in our Fiberstore.

Related Article: 10G SFP+ and 40G QSFP+ Transceivers Cabling Solutions

40G Data Center Cabling Solutions Comparison

QSFP+ and QSFP28 Transceivers Cabling Solutions


The short range 40-Gigabit Ethernet QSFP+ and 100-Gigabit Ethernet QSFP28 transceivers that are widely used in today’s data center use 12-fiber patch cables with female MPO connectors. The fiber can be either OM3 or OM4. The long range QSFP+ and QSFP28 transceiver use single-mode fiber patch cables with duplex LC connectors. This article may introduce the cabling solutions for QSFP+ and QSFP28 transceiver to you.

QSFP+ and QSFP28 Transceiver Types
In terms of 40G QSFP+ transceivers, from short range to long range, they are available in 5 common types. The minimum transmission distance is 100m, and the max transmission distance is 40km. 100G QSFP28 transceivers are commonly avaiable in 100GBASE-SR4 and 100GBASE-LR4 two types. Detailed QSFP+ and QSFP28 transceiver specifications are displayed in following tables.

Transceiver Type Interface Standard Connector Type Fiber Type
QSFP+ 40GBASE-SR4 Female MTP/MPO, key up 12-fiber multi-mode fiber (MMF) (OM3 or OM4)
QSFP+ 40GBASE-PLRL4 Female MTP/MPO, key up 12-fiber single-mode fiber (SMF) 1km
QSFP+ 40GBASE-PLR4 Female MTP/MPO, key up 12-fiber SMF 10km
QSFP+ 40GBASE-LR4 LC duplex SMF 10km
QSFP+ 40GBASE-ER4 LC duplex SMF 40km
QSFP28 100GBASE-SR4 Female MTP/MPO, key up 12-fiber MMF (OM3 or OM4)
QSFP28 100GBASE-LR4 LC duplex SMF 10km

12-Fiber Patch Cables with MTP Connectors
12-fiber patch cables with MTP connectors can be used to connect two transceivers of the same type—40GBASE-SR4-to-40GBASESR4 or 100GBASE-SR4-to-100GBASE-SR4. You can also connect 4x10GBASE-LR transceivers such as 40GBASE-PLRL4 and 40GBASE-PLR4 using patch cables—4x10GBASE-LR-to-4x10GBASE-LR—instead of breaking the signal out into four separate signals. Ensure that you order cables with the correct polarity. The MTP connectors on the 12-fiber cables should be key up (sometimes referred to as latch up, Type B, or Method B). If you are using patch panels between two QSFP+ or QSFP28 transceivers, ensure that the proper polarity is maintained through the cable plant.

12-Fiber MTP Patch Cables

12-Fiber MPO Patch Cables

12-Fiber Breakout Cables with MTP-LC Duplex Connectors
12-fiber breakout cables with MTP-LC duplex connectors can be used to connect a 4x10GBASE-LR or 4x10GBASE-SR transceiver to four separate 10GBASE-LR or 10GBASE-SR SFP+ transceivers. The breakout cable is constructed out of a 12-ribbon fiber-optic cable. The breakout cable splits from a single cable with an MTP connector on one end, into 4 cable pairs with 4 LC duplex connectors on the opposite end.

40G QSFP+ and 100G QSFP28 transceivers solution

40G to 4×10G

LC Duplex Patch Cables
Single-mode patch cables with LC duplex connectors can be used to connect two transceivers of the same type—40GBASE-LR4-to-40GBASE-LR4 or 100GBASE-LR4-to100GBASE-LR4. The SMF patch cable is one fiber pair with two LC duplex connectors at opposite ends.

LC Duplex Patch Cables

Related Article: Can I Use the QSFP+ Optics on QSFP28 Port?

10G SFP+ and 40G QSFP+ Transceivers Cabling Solutions


This article will discuss different connection methods between parallel Quad Small Form-factor Pluggable (QSFP+) transceivers and Small Form-factor Pluggable (SFP+) transceivers. As we know, a 40G QSFP+ transceiver can be either an 8-fiber parallel link or a 2-fiber duplex link. In this document when QSFP is used we will be discussing an 8-fiber parallel link. A SFP+ transceiver is usually an 2-fiber duplex link. According to standard, since QSFP+ is 40G interface, SFP+ is 10G interface, therefore four SFP+ transceiver must be needed to connect to one QSFP+ transceivers to achieve 40G transmission.

40G QSFP+ to 10 SFP+ Direct Connectivity Solutions
When directly connecting a QSFP port to the four corresponding SFP ports, an eight fiber MTP-LC breakout cable is required. The harness will have four LC Duplex connectors and the fibers will be paired in a specific way, assuring the proper polarity is maintained. This type of direct connectivity is only suggested for short distances within a given row or in the same rack/cabinet.

10G SFP+ and 40G QSFP+ direct connection

  • Polarity Drawing for Above Scenario 

Polarity Drawing for Direct Connectivity Solutions

40G QSFP+ to 10 SFP+ Interconnect Solutions
The 40G QSFP+ to 10 SFP+ interconnect solution shown in figure below shows one link with a breakout of the QSFP with the use of an MTP-LC module to four SFP links. A Type-B non-pinned MTP to non-pinned MTP cable is used between MTP-LC modulethe MTP-LC module and QSFP transceiver. The connection to the SFP transceivers is accomplished with Uniboot LC duplexed jumpers. This is a solution that is only recommended for short distances, where the patching takes place within a given row of racks/cabinets. This solution does present some disadvantages which are that ports 5 & 6 of the module are not being used thus reducing the patch panel density. It may also create some confusion when patching occurs since these two ports are dark.

SFP+ QSFP+ Interconnect Solutions

  • Polarity Drawing for Above Scenario Polarity Drawing for 10G SFP+ and 40G QSFP+ Interconnect Solutions

Unlike the patching approach in figure above, the solution shown in figure below has no dark fibers oLC-LC adapter panelr ports. The Type-B jumper is replaced with an eight-fiber harness. The modules are replaced with the LC-LC adapter panel. Using this approach allows full patch panel density that was lost in the previous example. Only two LC-LC adapter panels will be required for every three 8-fiber harnesses. All ports on the LC-LC adapter panels will be used and the connections to the 10GbE ports will be completed with an Uniboot LC duplexed jumper. This solution should also be deployed when there is a short distance between active components (within the same row). Note the LC panel does not support the LC Uniboot connector, only LC Duplex connectors with the triggers removed to avoid clearance issues with the panel cover.

10G 40G Interconnect Solutions

  • Polarity Drawing for Above Scenario 

Polarity Drawing for 10G SFP+ and 40G QSFP+ Solution

Fiberstore (FS.COM) provide all the products mentioned above, including 10G SFP+ transceivers, 40G QSFP+ transceivers, MTP patch cables, MTP-LC harness cable, MTP-LC module and LC-LC adapter panel. All in stock and can be shipped the same day.

Related article: It’s Time to Use MTP Cassettes in Your Network!

40GBASE-SR4/CSR4 QSFP+ Transceiver Direct Connection Cabling


As we all know, the standard specifies MPO as a connector to the 40GBASE-SR4/CSR4 QSFP+ transceiver. To connect a QSFP+ to QSFP+, we usually use a MTP 12-fiber trunk cable. In the 40GBASE-SR transmission, there are eight fibers associated with the channel—four fibers for the TX signal and four fibers for the RX signal. Therefore only 8 of the 12 fibers are used, where the remaining four are not used, and can optionally be not present in the cable. So we can also choose a MTP 8-fiber trunk cable for connectivity. This article explains 40G QSFP+ SR4/CSR4 transceiver to 40G QSFP+ SR4/CSR4 transceiver cabling selections.

How to Choose Right  MTP Trunk Cables? 
In addition to using a MTP 8-fiber trunk cable or MTP 12-fiber trunk cable, there are a number of other factors also needed to be considered when to choose a right MTP trunk cable for 40G QSFP+ SR4/CSR4 transceiver connectivity.

  • Use single-mode or multimode MTP trunk cable?

In the market, both single-mode and multiode MTP trunk cable are available. Which one should I use? According to 40GBASE-SR4 standards, 40G QSFP+ SR4 transceiver supports link lengths of 100 meters and 150 meters, respectively, on laser-optimized OM3 and OM4 multimode fibers. Therefore, to connect a 40G QSFP+ SR4  to 40G QSFP+ SR4, we should choose OM3 or OM4 multimode MTP trunk cables.

  • MTP trunk cable polarity selection: A, B or C?

In terms of MTP trunk cable, there are three kinds of polarity options (A, B and C). Which one to choose? In fact, according to the IEEE 40GBASE-SR4 specifications, we must select a type B MTP 8-fiber or MTP 12-fiber trunk cable. The type B trunk cable has opposing connectors with both keys oriented facing up, however the fiber positions are reversed at each end i.e. the fiber at position 1 at one end is connected to position 12 in the connector at the opposing end.


  • Choose male or female MTP trunk cable?

In terms of a MPO connector, it is divided into male and female types. They ensure that the adapter holds the connector with the correct ends aligned with each other. A MPO trunk cable usually has two MPO connector on each side. Therefore, MTP trunk cables are available in male–male and female–female two versions. According to IEEE standards, MPO optics in a 40G QSFP+ SR4 transceiver are always male connectors, and therefore will always accept female MPO connectors. So if we want to connect a 40G QSFP+ SR4 transceiver  to a 40G QSFP+ SR4 transceiver successfully, we must choose a female–female MTP trunk cable.

40G QSFP+ SR4/CSR4 to 40G QSFP+ SR4/CSR4 Cabling Selections
In order to satisfy different cabling requirement, we may choose different cabling methods. And different cabling methods call for many different cabling infrastructure. Following are four type common cabling methods to connect a 40GBASE-SR4/CSR4 QSFP+ to 40GBASE-SR4/CSR4 QSFP+.

  • Direct connection for 40 Gigabit Ethernet parallel optic transceiver

When directly connecting one QSFP+ MPO/MTP interface transceiver to another, a Type-B female MPO/MTP to female MPO/MTP cable is required. This type of direct connectivity is only suggested for short distances within a given row of racks/cabinets. Following picture shows two QSFP+ transceivers being connected with a MTP female cable.


Item Number FS Correlative Product Description FS Part Number
1 40GBASE-SR4 QSFP+, 850nm, 150m, MMF, MPO interface QSFP-SR4-40G
2 12 Fibers OM4, 12 Strands MTP Trunk Cable, Female to Female, Type B Polarity ( MTP/ MPO, OM4/ OM3 optional. Various lengths available) FS12OM4-2MTP-FF-B
  • 40GbE direct interconnect with MTP trunk cable and patch panel

For distances less than 400 meters, the use of FS MPO/MTP multi-mode fiber cabling is generally the preferred cabling method. The next solution is similar to the previous, but instead of using a 12-fiber jumper directly, the MPO/MTP adapter panel is interconnected. Following picture shows the distribution switch and FS optics and cabling options with corresponding item details for a QSFP+ to QSFP+ multi-mode interconnection.


Item Number FS Correlative Product Description FS Part Number
1 40GBASE-SR4 QSFP+, 850nm, 150m, MMF, MPO interface QSFP-SR4-40G
2 12 Fibers OM4, 12 Strands MTP Trunk Cable, Female to Female, Type B Polarity ( MTP/ MPO, OM4/ OM3 optional. Various lengths available) FS12OM4-2MTP-FF-B
3 12 Ports MTP/MPO Fiber Adapter Panel, key-up to key-up FAP-HV-12MTPUUD
  • 10Gig migrate to 40GbE by interconnecting MTP LGX cassette and MTP trunk cable

Following picture shows one link with a breakout of the QSFP+ with the use of an MPO/MTP LGX cassette to four 10G SFP+ links. A Type-B female MPO/MTP to Female MPO/MTP assembly is used between the MPO/MTP LGX cassette and 40GbE transceiver. The connections to the SFP+ transceivers is accomplished with OM3/OM4 Uniboot LC duplex fiber patch cables.


Item Number FS Correlative Product Description FS Part Number
1 10GBASE-SR SFP+, 850nm 300m, MMF, LC duplex SFP-10GSR-85
2 LC-LC Duplex 10G OM4, MMF Patch Cable OM4-LC-LC-DX-FS
3 12 Fibers OM4, LGX – MTP Cassette, MTP(male) to LC FS12OM4-LGX-2MTP-LC
4 MTP/MPO LGX Cassettes 1U/4U 19” Rack Mount FS-1RU-MX
5 12 Fibers OM4, 12 Strands MTP Trunk Cable, Female to Female, Type B Polarity ( MTP/ MPO, OM4/ OM3 optional. Various lengths available) FS12OM4-2MTP-FF-B
6 10GBASE-SR SFP+, 850nm 300m, MMF, LC duplex SFP-10GSR-85
  • 10Gig migrate to 40GbE by interconnecting MTP harness cable and MTP trunk cable

Sometimes, create a simple, cost-effective migration path by installing a structured cabling system that can support your future 40GbE networking needs. Following picture uses the 8-fiber harness as shown in the diagram to connect to 10G SFP+s. This approach allows for an easy upgrade path moving from 10Gig to 40GbE connectivity.


Item Number FS Correlative Product Description FS Part Number
1 10GBASE-SR SFP+, 850nm 300m, MMF, LC duplex SFP-10GSR-85
2 8 Fibers OM4, 12 Strands MTP Harness Cable, MTP to LC, Type B Polarity ( MTP/ MPO, OM4/ OM3 optional. Various lengths available) OM4-LC-LC-DX-FS
3 12 Ports MTP/MPO Fiber Adapter Panel, key-up to key-up FAP-HV-12MTPUUD
4 Empty 1RU/4RU Rack Mount Fiber Patch Panel FMT1-E-FS
5 12 Fibers OM4, 12 Strands MTP Trunk Cable, Female to Female, Type B Polarity ( MTP/ MPO, OM4/ OM3 optional. Various lengths available) FS12OM4-2MTP-FF-B
6 40GBASE-SR4 QSFP+, 850nm, 150m, MMF, MPO interface QSFP-SR4-40G

Fiberstore provides wide brand compatible 40G QSFP+ SR4 transceivers and all kinds of MTP cables. Each fiber optic transceiver has been tested to ensure its compatibility and interoperability. Please rest assured to buy. For more information or quotation, please contact us via

Related Article: 40G Transceiver Module: QSFP+ Module And CFP Module

Do You Know about Active Optical Cable (AOC Cable)?


Bandwidth usage is soaring, driven by the proliferation of Internet-connected devices. At this time, active optical cable (AOC cable) has emerged. Besides, the market of AOC cables keeps growing and has a broad prospect. What’s active optical cables? Why should we use it? In this article, some knowledge of active optical cables will be provided.

Introduction to Active Optical Cable (AOC Cable)
Active optical cable (AOC) is used for short-range multi-lane data communication and interconnect applications. Usually, the wire transmission of optical communication should belong to passive part, but AOC is an exception. AOC consist of multimode optical fiber, fiber optic transceivers, control chip and modules. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable without sacrificing compatibility with standard electrical interfaces. Since people expect more information to be available at their fingertips, our communications systems will need to be quicker, and AOC is one of the best solutions to solve this problem. Compared with direct attach copper cable for data transmission, AOC provides more advantages, such as lighter weight, high performance, low power consumption, low interconnection loss, EMI immunity and flexibility. At present, AOC is widely used in many fields as well as promoting the traditional data center to step into optical interconnection.

AOC cable

Differences Between Passive/Active DAC and Active Optical Cable (AOC Cable)
Passive cabling provides a direct electrical connection between corresponding cable ends. Active cables provide the same effect but, by embedding optics and/or electronics within the connectors, can overcome some of the limitations of passive cables. While passive cables are always copper-based, active cables can use either copper wire or fiber optics to provide the link between the cable ends. The picture below shows us the leading types of passive and active cables for data center.

Differences Between PassiveActive Copper and Active Fiber

 Why Use Active Optical Cable (AOC Cable)?
Primarily, active optical cable (AOC) assemblies were invented to replace copper technology in data centers and high performance computing (HPC) applications. As we know, copper passive twinax cable is heavy and bulky, making it difficult to physically manage the datacenter. And due to the nature of electrical signals, electromagnetic interference (EMI) limits copper’s performance and reliability. Though there are so many disadvantages of copper cable, at that time, it is the main stream while the idea of AOC cables almost seems too good to be true. However, the advantages of AOC cables make the predecessors look obsolete and unsophisticated, and changes the limitation of copper passive twinax cable as well as playing an important role in high speed data transmission. Nowadays, a variety of active optical cable have been launched in the market, such as 10G SFP+ AOCs, 40G QSFP+ to QSFP+ AOCs, 40G QSFP+ to 4 SFP+ breakout AOCs and ,40G QSFP+ to 8xLC breakout AOCs.

Active Optical Cable

FS.COM active optical cables achieve high data rates over long reaches which are the best solutions for high-performance computing and storage applications. We provide many AOC products such as 10G SFP+ AOCs, 40G QSFP+ AOCs, QSFP+ to 4 SFP+ AOCs, and QSFP+ to 8 x LC AOCs. In addition, customized active optical cables are available in various lengths, Cisco compatible and other options. For more detailed information, please visit or contact us over

Related Articles:

QSFP+ and QSFP28 Transceivers Cabling Solutions

40G Network Connectivity Solutions

Active Optical Cable (AOC) – Rising Star of Telecommunications

What Is the Difference Between Singlemode QSFP+ and Multimode QSFP+?


The singlemode and multimode QSFP+ here mean the transceivers which work at different types of optical fibers, ie singlemode type will work with singlemode fiber, while multimode one will work with multimode fiber. So, what’s the different between them? And what should we notice when using them? Which one should I choose? In this article, we will have a discussion around this topic.

Singlemode vs. Multimode QSFP+

  • Singlemode

Singlemode fiber (SMF) has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability for higher bandwidth and much longer distances in transmission. Singlemode QSFP+ works mainly in 1310nm wavelength and is mostly used in long distances transmission. There are many different types of them, and different type can achieve different transmission distance, such as 500m, 1km, 2km, 10km and 40km. he color of compatible fiber optic patch cord is yellow. SMF QSFP+ usually uses duplex LC connector, but there also are some types use MPO/MTP connector.

Singlemode QSFP+

  • Multimode

Multimode fiber (MMF) uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in MMF have a higher capability to gather light from the laser. In practical terms, this means the optics are cheaper. The common multimode QSFP+ works in 850nm wavelength and is only used for short distance transmission reaching 100m and 500m. Though it’s not able to transport for long distance, it can transport many kind of optical signals. It usually uses MPO/MTP connector, but some SMF&MMF ones can also use duplex LC connector.

Multimode QSFP+

Choose a Singlemode or Multimode QSFP+?
SMF and MMF QSFP+ may have different transmission distance and connectors, which is the most important factors you should consider when to make a decision. In the table below, I display the specifications of some main SMF and MMF 40G modules. Hope to help you to choose the right one for your network.

Type Wavelength Fiber and Distance Connector Original model
40GBASE-SR4  4x850nm 100m(OM3) 150m(OM4) Male MPO Cisco 40G-SR4
40GBASE-CSR4  4x850nm 300m(OM3) 400m(OM4) Male MPO Cisco 40G-CSR4
40GBASE-LX4  1270,1290,1310,1330 nm 100m(OM3) 150m(OM4) 2km(SMF) Duplex LC Juniper JNP-QSFP-40G-LX4
40GBASE Universal  1270,1290,1310,1330 nm 150m(OM3) 150m(OM4) 500m(SMF) Duplex LC Arista QSFP-40G-UNIV
40GBASE-PLRL4  4x1310nm 1km(SMF) Male MPO Arista QSFP-40G-PLRL4
4x10GBASE-LR Lite 4x1310nm 2km(SMF) Male MPO Finisar FTL4P1QL1C
40GBASE-LR4  1270,1290,1310,1330 nm 10km(SMF) Duplex LC Cisco 40G-LR4
40GBASE-LR4-Lite 1270,1290,1310,1330 nm 2km(SMF) Duplex LC Finisar FTL4C1QL1C
40GBASE-LRL4  1270,1290,1310,1330 nm 1km(SMF) Duplex LC Arista 40G-LRL4
40GBASE-PLR4  4x1310nm 10km(SMF) Male MPO Arista 40G-PLR4
40GBASE-ER4  1270,1290,1310,1330 nm 40km(SMF) Duplex LC Cisco 40G-ER4

What Should We Notice When Using Singlemode & Multimode QSFP+

  • Ensure that the transceiver 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.
  • In general, to ensure the data accuracy, short-wave QSFP+ modules use with multimode fibers (ie. aqua OM3 or OM4 fiber patch cord), while long-wave modules use with single-mode fiber (ie. yellow fiber patch cord).
  • Do not over bend or winding fiber optic cables when using them. This will increase the attenuation of light in transit.
  • If you don’t use this module, you must use the dust plug to protect the optical bore.

When we choosing the QSFP module, we must confirm the transmission distance and wavelength we want to use in. This will help us to choose the right QSFP modules more efficiently. In addition, the costs for transceiver modules which keep adding up over time will be a budget pressure for many users. To save more, we can choose the compatible module without sacrificing any quality or reliability but only with a low cost. Fiberstore, an excellent supplier, supplies 100% compatible fiber optic transceiver modules of many brands, such as Cisco, HP, Juniper, Brocade, Finisar etc. with a incredible discount that may be a good choice for you.

Related Article: QSFP BiDi – 40GbE Over LC Duplex Multimode Fiber

40G Network Connectivity Solutions


High speed and wide bandwidth demands drive data centers to consolidate into more complex systems. The speed of data center now is increasing to 40G and eventually to 100G. How to achieve 40G connectivity? In fact, we need some new optical technologies and cabling infrastructure. In this post, I will introduce some commonly used qsfp and qsfp cable for 40G connectivity.

40G QSFP Modules
As we know, fiber optic transceiver is an electronic device that receives an electrical signal, converts it into a light signal, and launches the signal into a fiber. It also receives the light signal, from another transceiver, and converts it into an electrical signal. It is the key component in fiber optic transmission. The basic interface of 40G pluggable optical modules are 40GBASE-LR4 and 40GBASE-SR4 in QSFP+ form factor.


40GBASE-SR4 transceivers are used in data centers to interconnect two Ethernet switches with 8 fiber parallel multimode fiber OM3/OM4 cables. It can support the transmission distance up to 100 m with OM3 fiber and 150 m with OM4 fiber. The optical interface of 40GBASE-SR4 is MPO/MTP. This module can be used for native 40G optical links or in a 4x10G mode with parallel to duplex fiber breakout cables for connectivity to four 10GBASE-SR interfaces.

40GBASE-LR4 QSFP+ transceiver support with a link length up to 10 kilometers over 1310 nm 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. It is most commonly deployed between data-center or IXP sites with single-mode fiber.

QSFP+ Cables
QSFP+ cable is designed to meet emerging data center and high performance computing application needs for a short distance and high density cabling interconnect system capable of delivering an aggregate data bandwidth of 40Gb/s. QSFP+ cables are suitable for very short distances and offer a highly cost-effective way to establish a 40G link between two switches within racks and across adjacent racks. These high speed cables provide a highly cost-effective way to upgrade from 10G to 40G or 40G to 40G interconnect connection.

1. Passive and Active Direct Attach Copper Cables
The 40g passive or active direct attach copper cables (DAC) are designed with twinax copper cable and terminated with QSFP+ connectors. The main difference between passive DAC and active DAC is that the passive one is without the active component. Therefore, active QSFP+ DAC can achieve a longer transmission distances than passive QSFP+ cable.


2. Active Optical Cable (AOC cable) Assemblies
Active optical cable, namely AOC brings a more flexible cabling than direct attach copper cables with the advantages of lighter weigth, longer transmission distance and higher performance for anti-EMI. Now, 40G AOC cable are popular with users.


MPO/MTP Cable Series
Since 40GBASE-SR4 and 40GBASE-CSR4 both use MPO/MTP connector. Therefore, in addition to fiber optic transceivers and direct attach cables, MTP cabling series usually needed to achieve 40G connectivity. This series include MTP trunk cables, MTP-LC harness/breakout cables, LC or MTP patch cables, MTP-LC cassette modules, MTP adapter panels and MTP rack mount holders.

MPOMTP Cabling Series

Fiberstore offers a comprehensive solution for 40G network connectivity. What’s more, products such as 40GBASE-LR4 and 40GBASE-SR4 modules are in stock and can shipped in 12hrs. For more information, please visit

Related article: Do You Know about Active Optical Cable (AOC Cable)

40GBASE-LR4 QSFP+ Transceiver Links: CWDM and PSM


As we all know, 40GBASE-SR4 QSFP+ transceivers usually use a parallel multimode fiber (MMF) link to achieve 40G. 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+ transceivers, there are two kinds of links. One is coarse wavelength division multiplexing (CWDM) and the other is parallel single-mode fiber (PSM). What’s the difference between them? In this article, I will show their working principles to you respectively.

40GBASE-LR4 CWDM QSFP+ Transceiver
QSFP-40G-LR4The 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 this transceiver is 10km. To minimize the optical dispersion in the long-haul system, single-mode fiber (SMF) has to be used. This 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 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).


40GBASE-LR4 PSM QSFP+ Transceiver
40G-LR4 QSFPUnlike CWDM QSFP+ transceiver which uses a LC connector, PSM QSFP+ 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. Proper alignment is ensured by the guide pins inside the receptacle. The cable usually cannot be twisted for proper channel to channel alignment. In terms of a PSM QSFP+, the transmitter module accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver module converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels. All data signals are differential and support a data rates up to 10.3G per channel.


What’s the Difference?
From an optical transceiver module structure viewpoint, PSM seems more cost effective because it uses a single uncooled CW laser which splits its output power into four integrated silicon modulators. Besides, its array-fiber coupling to an MTP connector is relatively simple. However, from an infrastructure viewpoint, PSM would be more expensive when the link distance is long, mainly due to the fact that PSM uses 8 optical single-mode fibers while CWDM uses only 2 optical single-mode fibers. A summary table comparing the key differences between CWDM and PSM is shown below:

Optical TX 4 uncooled 1300nm CWDM directly-modulated laserswavelength spacing 20 nm 4 integrated silicon photonic modulators and one CW laseruncooled 1300nm DFB laser
4-wavelength CWDM multiplexer and demultiplexer Needed No need
Connector Duplex LC connector MTP/MPO fiber ribbon connector
Cable Via 2 optical single-mode fibers Via 8 optical single-mode fibers

In addition, the caveat is that the entire optical fiber infrastructure within a data center, including patch panels, has to be changed to accommodate MTP connectors and ribbon cables, which are more expensive than conventional LC connectors and regular SMF cables. What’s more, cleaning MTP connectors is not a straightforward task. Therefore, CWDM is a more profitable and popular 40G QSFP link.

For 40GBASE-LR4 QSFP+ transceivers, either CWDM link or PSM link, the maximum transmission distance is both 10km. 40GBASE-LR4 CWDM QSFP+ transceivers use a duplex LC connector via 2 optical single-mode fibers to achieve 40G. However, 40GBASE-LR4 PSM QSFP+ transceivers use an MTP/MPO fiber ribbon connector via 8 optical single-mode fibers to reach 40G. Therefore, CWDM QSFP+ enables data center operators to upgrade to 40G connectivity without making any changes to the previous 10G fiber cable plant, which is more cost-effective and widely used by people. Fiberstore provides wide brand compatible 40G CWDM QSFP+ transceivers, such as Juniper compatible JNP-QSFP-40G-LR4 and HP compatible JG661A. In Fiberstore, each fiber optic transceiver has been tested to ensure its compatibility and interoperability. Please rest assured to buy. For more information or quotation, please contact us via

Related Article: 40G Transceiver Module: QSFP+ Module And CFP Module