Author Archives: Angelina.Li

Will Single-mode Fiber Work Over Multimode SFP Transceiver?

Network installers usually come across a situation that device you have in your network does not always fit and work perfectly with the fiber. They plan to make a cable plant based on the multimode cabling, but owing to the link limitation or other reasons, they have to connect multimode equipment with single-mode devices. Is it feasible? Or put it more specifically, can I use the multimode SFP over single-mode fibers or vice versa? This article will give you a detailed illustration about the feasibility of the solutions, and introduce two relevant devices (mode conditioning cable and multimode to single-mode fiber media converter).

Single-mode Fiber Over Multimode SFP—You Can If You Are Lucky

This is the question that has been asked so many time, but no one can give the exact answer—yes or no. Hence, let’s illustrate it in details.

Most people think single-mode and multimode fibers are not interchangable because of the wave length of the laser and core size of the fiber. Single-mode fiber (MMF) uses a laser as a light source (the light beam is very concentrated), while multimode fiber (MMF) uses an LED to generate the signal. This would require two significantly different devices to generate the signal.

The core sizes are drastically different between SMF and MMF. SMF is 9 micron and multimode is 62.5 or 50 micron. If users try to mix the single-mode and multimode cabling in the same network, they might have trouble dealing with the two different types of signal.

However, it is possible to interconnect two devices using SMF interfaces at one end and MMF receiver at the other end. Keep in mind that it depends on the devices, so you can if you are lucky. When plugging LC single-mode duplex fibers on the multimode fiber transceiver (1000GBASE-SX) in the network, you will find the link came up (the light on the switch turns green). Therefore, the multimode fiber transceiver connected by the single-mode fibers works for short-reach application. The following image is the real screenshot of the single-mode fibers inserting into the 1000BASE-SX SFP.

real screenshot of inserting single-mode fiber over multimode fiber transceivers

While it should be stressed that the link is not reliable and it only works for particular brand devices with a very short link length. Many sophisticated vendors like Huawei, Alcatel or Cisco do not support it. Nevertheless, owing to the differential mode delay (DMD) effect, signal loss of this connection is not acceptable, either.

To sum up, this might be feasible but not advisable. If you need to make a connection between single-mode and multimode interfaces, you’d better use the intermediate switch that is able to convert the signals between single-mode and multimode fibers. The following part will introduce two solutions that might be helpful for the multimode and single-mode conversion.

Solution 1: MCP Cable—Single-mode In and Multimode Out

As to the multimode fiber with single-mode SFPs, most people mention the mode conditioning patch (MCP) cables. The MCP cable is launched to support 1000BASE-LX optics over multimode cable plant. The mode conditioning cables allow customers to successfully run Gigabit Ethernet over our multimode cable using single-mode fiber transceivers, Cisco 1000BASE-LX/LH SFP is the special type of transceiver that can both support single-mode and multimode fibers. The image below displays the difference between standard SC multimode patch cable and SC mode conditioning patch cable.

comparison between standard SC multimode fiber patch cable and SC MCP cable

Then, in this situation, you can run successfully from a single-mode fiber transceiver over multimode fiber with the use of MCP cables, but the distance will not exceed the link specification for multimode transceivers. Otherwise, there will be much signal loss in the cable run.

In general, if you want to run multimode fiber optic cable over 1000BASE-LX SFPs, you can use the mode conditioning cable. However, mode conditioning patch cords are required for link distances greater than 984 feet (300 meters). For distance less than 300 m, please omit the mode conditioning patch cords (although there is no problem using it on short links).

Solution 2: Fiber to Fiber Media Converter—Conversion Between Multimode and Single-mode Fibers

As noted before, mode conditioning cables, to some extent, can realize the connection between single-mode to multimode, but you can not say that you can convert single-mode to multimode or vice versa. Mode conversion between multimode and single-mode fibers often requires fiber to fiber media converters or the single-mode to multimode fiber converter.

F2F-10G-Multimode-to-Single-mode

In the above diagram, two Ethernet switches equipped with multimode fiber ports are connected utilizing a pair of fiber-to-fiber converters which convert the multimode fiber to single-mode and enable network connectivity across the distance between Gigabit switches.

Conclusion

It doesn’t really make much sense to use the single-mode fiber transceivers with multimode fibers in your network or vice versa, although the link will come up. Like I said above, you can if you are lucky connect. MCP cables and fiber to fiber converter are the two available options for single-mode and multimode connection. If you bought the wrong fiber optic cables, just replace it into the right one. Fiber optic cables and optical transceivers modules nowadays are very cheap. You won’t need to risk of mixing them in the same network.

Original Source : Single-mode Fiber Work Over Multimode SFP Transceiver

QSFP+ to SFP+ Adapter (QSA) Module Vs. QSFP+ to SFP+ Breakout Cable

People frequently ask about feasible solutions between 10G and 40G servers. QSFP+ breakout cables like QSFP+ to 4 SFP+ cables and MTP to 4 LC harness cables are the commonly used equipment to connect between QSFP+ ports and SFP+ ports. But recently, Cisco launched a new type of product—QSFP+ to SFP+ Adapter (QSA) module that could provide a smooth migration to 40 Gigabit Ethernet. Is it a better solution for the 10G to 40G migration? Should I use the QSA module or 40G QSFP+ breakout cable? This article will answer the above questions and provide some suggestions to you.

QSA Module—Is It a Better Solution for the 40G Migration?

The QSFP+ to SFP+ Adapter module, specified by Cisco, is the module built in QSFP+ form factor with a receptacle for SFP+ cable connector at the back (seen in the below image). When connecting the QSFP port to an SFP+ port, QSA module usually acts as an interface for SFP+/SFP cables. That means you can effectively plug in an SFP+/SFP optics operating at a 10 Gbps port on this module, then inserting the module into a QSFP port cage to realize the 40G Ethernet transition. QSFP+ to SFP+ adapter module ensures the smooth connectivity between 40 Gigabit Ethernet adapter and 10 Gigabit hardware using SFP+ based cabling. Therefore, once the QSA module came out in 2016, it was soon considered as the effective solutions for converting 40G ports to the 10G ports.

Cisco QSFP+ to SFP+ adapter cable

40G QSFP+ Breakout Cables Overview

People usually use either the QSFP+ to 4 SFP+ breakout cables or MTP to LC harness cables to convert the downlink 40G port of ToR (Top of Rack) access layer switch into 4x10G fan out mode, then connect to the 10G cabinet server port. QSFP+ to SFP+ breakout cable including the direct attach copper cable (DAC) and active optical cable (AOC) consists of a QSFP+ connector on one end and four SFP+ connectors on the other end. The cables use high-performance integrated duplex serial data links for bidirectional communication on four links simultaneously.

QSFP+ to SFP+ breakout cable

While the MTP to LC harness cable have one one MTP cables on the one end and four LC connectors on the other end. This type of cable is recommended to be used in the same rack within the short distance. The picture above shows the direct connectivity between the QSFP+ transceivers and SFP+ transceivers by using the MTP to LC harness cable.

QSA Module or QSFP+ Breakout Cable

In this part, I will make a comparison between QSFP+ to SFP+ adapter modules and QSFP+ breakout cables from the aspects of cost, performance and compatibility.

Cost—QSFP+ Breakout Cables Wins

QSFP+ to SFP+ adapter module is not certificated by Multi-source Agreement (MSA), but a sole source paradigm defined by few vendors. The only vendor owns its patent, so the QSA modules on the market are quite expensive. Nevertheless, QSFP+ breakout cables covered in the MSA standard, support both copper and optical connectivity, which are much cheaper than QSA modules. Cost comparison between QSA module and QSFP+ breakout cable (DAC, 1m) is listed in the below table.

cost comparison between QSA module and QSFP+ breakout cable

Performance

With QSA module, users have the flexibility to use any SFP+/SFP optics to connect to the 40Gbps data rate with a single 10G connection. However, QSA module only exists in 10G-40G speed, which also explains the reasons of its unpopularity of the market. QSFP+ to 4 SFP+ breakout cables split the 40G channel into 4x10G channel which provide four times more data transfers than QSA module does.

Compatible Switch and SFP/SFP+ Modules

QSA modules, according to Cisco, are available in 40 Gigabit Ethernet compatibility matrix. Cisco SFP/SFP+ transceivers that can be plugged into the QSA modules are concluded as Cisco 10GBASE-SR, LR, ER, ZR, DWDM SFP+, FET-10G and 10G SFP+ cable as well as SFP (1000BASE-T, SX, LX, EX, ZX). As for the QSFP+ to SFP+ breakout cables, different vendors have different compatible issues. Keep in mind that you should find the reliable fiber optic transceiver manufacturers.

Reminder:

  • Before using the QSA modules or the QSFP+ breakout cables to connect a 40 Gigabit Ethernet port to a 10 Gigabit SFP+ port, you must enable the fan-out mode of your devices.
  • Not all the 40G cards and switches can be split into 4x 10Gb mode, for example, the Mellanox QSFP cards do not support the QSFP to SFP+ breakout, but their switches can.
  • With the QSA module, you can directly use the SFP+ modules in a QSFP+ port, but you cannot use the QSFP+ optical cables in a QSA setup.
  • Telecom industry has been modified rapidly. Hence, it is more cost-effective to make additional investment in high-speed switches instead of breakout cables and expensive QSA modules.
Conclusion

Both the QSFP+ breakout cables and QSA modules provide a smooth migration to the 40 Gigabit Ethernet. With these optics, you can reuse the existing 10G SFP+ cables, optical transceivers and switches when upgrading to 40G Ethernet. QSFP+ breakout cables is regarded as the cost-effective and reliable solutions for the most situations, but QSA module is preferable for the application with a single 10G connection.

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.

Conclusion

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.

100G QSFP28 PSM4 to Address 500m Links in Data Center

100G QSFP28 PSM4 optics is a type of 100G optical transceiver that provides a low-cost solution to long-reach data center optical interconnects. 100G PSM4 (parallel single-mode 4 lane) standard is mainly targeted to data centers that based on a parallel single-mode infrastructure for a link length of 500 m. Compared with the hot-selling 100GBASE-SR4 and 100GBASE-LR4 optics, 100G QSFP28 PSM4 recently wins the popularity among the overall users. This article will provide a complete specification of the 100G QSFP28 PSM4 transceiver and explain the reason why people would need QSFP28 PSM4.

QSFP28 module

QSFP28 PSM4—A Low-Cost but Long-Reach Solution

100G QSFP28 PSM4 is compliant with 100G PSM4 MSA standard, which defines a point-to-point 100 Gb/s link over eight parallel single-mode fibers (4 transmit and 4 receive) up to at least 500 m. PSM4 uses four identical lanes per direction. Each lane carries a 25G optical transmission. The 100G PSM4 standard is now available in QSFP28 and CFP4 form factor. Table 2 shows the diagram of the 100G QSFP28 PSM4 Specification. 100G PSM4 is a low-cost solution. Its cost structure is driven by the cost of the fiber and the high component count. FS.COM offers the Cisco compatible 100G QSFP28 PSM4 at US$750.00.

diagram of QSFP28 PSM4

As you can see in the above image, 100G QSFP28 PSM4 transceiver uses four parallel fibers (lanes) operating in each direction, with transmission distance up to 500 meters. The source of the QSFP28 PSM4 module is a single uncooled distributed feedback (DFB) laser operating at 1310 nm. It needs either a directly modulated DFB laser (DML) or an external modulator for each fiber. The 100GBASE-PSM4 transceiver usually needs the single-mode ribbon cable with an MTP/MPO connector.

Why Do We Need 100G QSFP28 PSM4?

100G PSM4 is the 100G standard that has been launched by multi-source agreement (MSA) to enable 500m links in data center optical interconnects. But as we all know, there are several popular 100G interfaces out there on the market, such as QSFP28 100GBASE-SR4, QSFP28 100GBASE-LR4, QSFP28 100GBASE-CWDM4, and CFP 100GBASE-LR4, etc. So with so many options, why do we still need 100G QSFP28 PSM4?

To better help you make up your mind, you need to figure out the following questions:

Q1: What are the net link budget differences between PSM4, SR4, LR4 and CWDM?
Table 3 displays the detailed information about these 100G standards.

100GBASE-PSM4 100GBASE-CWDM4 100GBASE-SR4 100GBASE-LR4
4-wavelength CWDM multiplexer and demultiplexer No need Need No need Need
Connector MPO/MTP connector Two LC connectors MPO/MTP connector Two LC connectors
Reach 500 m 2 km 100 m 10 km

Note: the above diagram excludes the actual loss of each link (it is the ideal situation). In fact, WDM solution are at least 7 db worse link budget than PSM4. For a 2 km connectivity, a CWDM module will have to overcome about 10 db additional losses compared to PSM4. And the 100G LR4 optics at 10 km is 12 db higher total loss than PSM4.

Q2: What power targets are achievable for each, and by extension what form factors?
According to the IEEE data sheet, the WDM solutions cannot reasonably fit inside QSFP thermal envelop, while PSM4 can fit inside the QSFP thermal envelope. That means you would need the extra power for the WDM solution of your network. But if you use the QSFP PSM4, this won’t be a problem.

All in all, a 100G QSFP28 PSM4 transceiver with 500m max reach is a optional choice for customers. Because other 100G optics are either too short for practical application in data center or too long and costly. QSFP28 PSM4 modules are much less expensive than the 10 km, 100GBASE-LR4 module, and support longer distance than 100GBASE-SR4 QSFP28.

Summary

QSFP28 PSM4 is the lowest cost solution at under one forth the cost of either WDM alternatives. 100G QSFP28 PSM4 can support a link length of 500 m, which is sufficient for data center interconnect applications. 100G QSFP28 PSM4 also offers the simplest architecture, the most streamlined data path, higher reliability, an easy upgrade path to 100G Ethernet.

MPO Cable Testing Overview

Nowadays, the existing bandwidth is not adequate to meet enterprises’ increasing appetite. In the meanwhile, optical technologies like cloud computing, virtualization and storage area networks are all in the fast development, which pushes the further development of higher-bandwidth tech like 40/100G Ethernet. Thus under this circumstance, new devices are greatly required. Besides the new optical transceivers and fiber optic cables, a steady proliferation of fiber connections—MPO (Multifiber Push-On) came into being.

MPO cables, featured by its compact, pre-terminated advantages, has become the default cabling solution for the increasing bandwidth requirements. However, a flaw of the MPO cable may hinder its development. The testing process of the MPO cable can be complex and error-prone. Have you been through the scene? When you prepare to test a MPO cable, you have to throw polarity of all 12 fiber connections into the mix. And if it comes to migrating 10 Gbps to 40/100 Gbps on the same cable, all the testing job you have done is in vain. Since the testing process is pretty uneasy, The following text will provide some detailed information about it to help you do the right MPO cable testing.

MPO cable

Problems You Should Know About MPO Cable Testing

Typically, a MPO cable contains 12 optical fibers, and each fiber is thinner than human’s hair. So if you want to test the cable, you must test every fiber of it, which is quite difficult for inexperienced engineers. The common way to do this is to use a fan-out cord to make the 12 fibers separate, then testing. One fiber testing would take you 10 seconds. So if your customer ask you to test 48 MPO trunks cable in data center which has a 30,000-MPO data center installation, that means you need to spend 3,120 hours. Such a huge project! To avoid this expensive and time-consuming process, modular factory-terminated MPO cables promise simplicity, lower cost, and true plug-and-play fiber connectivity.

Additional, when you are about to test a MPO cable, you should check whether the MPO cable is in the good state. Because cables must be transported, stored, and later bent and pulled during installation in the data center, which may lead to the performance uncertainties before fiber cables are deployed. Proper testing of pre-terminated cables after installation is the only way to guarantee performance in a live application.

What’s more, fiber polarity is also an important factor you should take into account. The simple purpose of any polarity scheme is to provide a continuous connection from the link’s transmitter to the link’s receiver. For array connectors, TIA-568-C.0 defines three methods to accomplish this: Methods A, B and C. Deployment mistakes are common because these methods require a combination of patch cords with different polarity types.

The Relationship Between Bandwidth and Testing

The market trend of telecom industry implies that 10G network has already been deployed in a large scale. And now 40G is main stream. As for 100G, people also already prepare for it. So bandwidth would always be a hot topic.

We have said before that MPO cable can solve the problem of bandwidth. As data center bandwidth steadily climbs to 10, 40, and 100Gbps, a dense multi-fiber cable becomes the only option. That’s why the use of MPO cables has steadily risen over the past 10 years. With the MPO cabling system, 40/100G migration path seems to be a simple and easy solution. Just remove the 10Gbps cassette from the MPO cable and replace it with a bulkhead accommodating a 40Gbps connection. Later it might be possible to remove that bulkhead and do a direct MPO connection for 100 Gbps at a later date. Figure 2 shows a 40G connectivity with the use of the 12-fiber MPO cable. A 40G QSFP like QSFP-40G-SR4 connects to a 12-fiber MPO cable. A 12-fiber MPO fanout cable is also used to connect four 10G SFP+ transceivers like 46C3447 with a MPO FAP.

40G connectivity

The problem is that while this migration strategy is an efficient way to leverage the existing cabling, in comparison to 10Gbps connections, the 40Gbps and 100Gbps standards call for different optical technology (parallel optics) and tighter loss parameters. In short, each time you migrate you need to verify the links to ensure the performance delivery the organization requires.

How to Do the Proper MPO Cable Testing

When you move to this part, you may think that MPO testing may be a tough obstacle for us to conquer. So is there a simple way to do the testing? The answer is yes. You can just test all 12 fibers—the whole cable—simultaneously and comprehensively (including loss and polarity). That sort of test capability changes the fiber landscape, enabling installers and technicians to efficiently validate and troubleshoot fiber—flying through the process by tackling an entire 12-fiber cable trunk with the push of a button.

MPO cable testing tool

To do a proper MPO cable testing, you must need some proper testing tools as shown in Figure 3. The tools to perform this type of test are emerging on the market, and promise to reduce the time and labor costs up to 95% over individual fiber tests. Characteristics to look for in such a tool include the following parts.

  • An onboard MPO connector to eliminate the complexity and manual calculations associated with a fan-out cord.
  • A single “Scan All” test function that delivers visual verification via an intuitive interface for all 12 MPO fibers in a connector.
  • Built-in polarity verification for end-to-end connectivity of MPO trunk cables.
  • “Select Individual Fiber” function that enables the user to troubleshoot a single fiber with more precision.

Summary

The insatiable need for bandwidth ensures that the integrity of the data center, which has also become inextricably linked to the strength of the fiber cabling infrastructure. Now more and more MPO trunk cables are put into use, to make sure the better performance, you should be able to test the MPO connection. Fiberstore offers a variety of MPO products including MPO trunk cables, MPO harness cable, 12-fiber or 24-fiber MPO cable and so on. All of our products can also be customized. Please feel free to contact us.

Guide to Multimode Fiber Cabling in 40/100G Migration

Nowadays one and 10 Gbqs data rates are not adequate to meet the continued requirement for expansion and scalability in the data center, thus technology evolves and standards are completed to define higher data rates such as 40/100G Ethernet. In the meanwhile the cabling infrastructures installed today must provide scalability to accommodate the need for more bandwidth in support of future applications. OM3 and OM4 multimode cabling solutions have been proven to be a cost-effective solution for 40G data center. Today’s article will make you familiarize with this new Gigabit Ethernet and OM3/OM4 cabling to help you smoothly upgrade to 40G Ethernet.

Multimode Fibers in Data Center

Multimode fiber is more popular in data centers than singlemode fiber. Many people may know the reason—budget. Because the price of multimode fiber is typically much lower than singlemode fiber. Additionally, multimode fibers utilizes the low cost 850nm optical transceiver for both serial and parallel transmission. While singlemode fiber uses the expensive 1310nm and 1550nm transceiver and duplex fiber wavelength division multiplexing (WDM) serial transmission. Therefore, most data center designers would choose multimode fiber for 40/100G transmission.

OM3 and OM4 cable

There are four common types of multimode fibers available in the market—OM1, OM2, OM3 and OM4. Recently OM3 and OM4 cables are gradually taking place of OM1 and OM2 multimode cable. OM3 and OM4 are laser-optimized multimode fibers with 50/125 core, which are designed to accommodate faster networks such as 10, 40 and 100 Gbps. Compared with OM1 (62.5/125 core) and OM2 (50/125 core), OM3 and OM4 can support high data rate and longer distance. This is why OM3 and OM4 is more popular in data center.

The Ratification of IEEE 802.3ba

The Institute of Electrical and Electronics Engineers (IEEE) 802.3ba 40G/100G Ethernet standard was ratified in June 2010. According to this standard, it includes detailed guidance for 40/100G transmission with multimode and singlemode fibers. But the standard does not have guidance for Category-based unshielded twisted-pair or shielded twisted-pair copper cable.

OM3 and OM4 are the only multimode fibers included in 40/100G standard. Because multimode fiber uses parallel-optics transmission instead of serial transmission due to the 850-nm vertical-cavity surface-emitting laser (VCSEL) modulation limits at the time the guidance was developed. Compared to traditional serial transmission, parallel-optics transmission uses a parallel optical interface where data is simultaneously transmitted and received over multiple fibers. Table 2 shows the IEEE standards for 40 and 100 GbE.

IEEE standards for 40 and 100 GbE

The 40G and 100G Ethernet interfaces are 4x10G channels on four fibers per direction, and 10x10G channels on 10 fibers per direction, respectively. For 40GBASE-SR4 transceivers, it utilizes multimode fiber for a link length of 100m over OM3 and 150m over OM4. QSFP-40G-SR4 is Cisco 40GBASE-SR4 QSFP+ that can both operate over OM3 and OM4 cables to achieve 40G connectivity just as FTL410QE2C.

OM3 or OM4?

As noted before, OM3 and OM4 can meet the requirement for 40G migration cabling performance, that’s why they are being widely utilized in 40/100G migration. But OM3 and OM4, which is better for your infrastructure? There is no exact answer to this question as numerous factors can affect the choice. The working environment and the total costs are always the main factors to be considered when selecting OM3 or OM4 multimode cable.

OM3-and-OM4

OM3 is fully compatible with OM4. They use the same optical connector and termination of connector. The main difference between them is in the construction of fiber cable that makes OM4 cable has better attenuation and can operate higher bandwidth at a longer distance than OM3. On the other hand, the cost for OM4 fiber is higher than OM3. As 90 percent of all data centers have their runs under 100 meters, choosing OM3 comes down to a costing issue. However, in the long term, as the demand increases, the cost will come down. OM4 will become the most viable product in the near future.

Conclusion

No matter choosing OM3 or OM4 for your infrastructure, 40G migration is in the corner. OM3 and OM4 multimode cable featured by the high performance and low cost are the perfect solution for 40/100G migration. Fiberstore is committed to provide the best-service and high-quality products to customers. Our comprehensive range of products in OM3 and OM4 offer customers the ability to create the optimal network. For more information, you are welcome to contact us.

The Reality of Copper and Fiber Cable

The war between copper and fiber has been raged for years and it is never ended. Copper-based systems maintain the same upgrade path that they have for years, while fiber-optic proponents continue to advocate their sense of superiority, which forces people to face the dilemma of selecting copper or optical fiber. So, once again, which cabling type is the best overall value for their current and projected future needs? This article carefully looks into the question and gives you the reality of the present copper and fiber cables.

Major Difference Between Copper and Optical Fiber

Cable length and data rates are two of the key criteria that differentiate the use of copper or fiber optic cable. If you require a long link length and high data rate, then fiber cable may be the obvious choice, and you can move on to selecting a specific fiber cable. Alternatively, if the runs are short and the data volume fits within copper’s capacity, then copper it is. Some other general differences between copper and fiber optic cables are offered in the table. Once you understand the distinct properties of copper and fiber, your solution may seem clearer. Now let’s come to the reality of both cables to help you select the suitable one.

difference between copper and fiber cable

Copper Cabling in Gigabit Ethernet Application

Category 6 or Cat6 data cabling as one of the most popular copper cables in the market today, has been utilized for Gigabit Ethernet and several other network protocols. As the sixth generation Ethernet cables formed from twisted pairs of copper wiring, cat6 is composed of four pairs of wires, similar to cat5 cables. The primary difference between the two, though, is that cat6 makes full use of all four pairs. This is why cat6 can support communications at more than twice the speed of cat5e, allowing for Gigabit Ethernet speeds of up to 1 gigabit per second.

copper cabling

However, there are some link restrictions in using this type of data cabling. When used for 10/100/1000BASE-T, the restriction of the copper cable is 100 meters, and when used for 10GBASE-T, the restriction is 55 meters. Another issue is that there are some cat6 cables that are very large and are quite difficult to connect to 8P8C connectors (a type of modular connector used for communications purposes such as phone/Ethernet jacks) when the user does not have a unique modular piece.

Copper cable still has a place in the telecom field, the best prove is that copper cable has improved itself to face the ever-increasing bandwidth requirement. For 40G Ethernet, there are 40G DAC cables — passive copper cable or active copper cable available in the market to achieve 40G connectivity. For example, Cisco QSFP to QSFP+ copper cables, like QSFP-H40G-CU1M and QSFP-H40G-ACU7M are widely used to connect within racks and across adjacent racks.

Fiber Optic Cabling

Fiber optic cable is completely unique from cat6 and other types of copper cabling systems. The most obvious feature about optical fiber is that it draws on light instead of electricity to transmit signals. In addition, optical fiber is immune to electrical interference, which means that a user can run it just about anywhere, anytime. However, fiber is not that easy to install. Terminating fiber optic cable is not as simple as copper. While manufacturers have developed crimp-on connectors, they are expensive, high loss and have not been very reliable. Fiber optic connectors need adhesives for reliability and low cost. And most installation involves stripping fibers, injecting adhesives and polishing the ends. No IDC (insulation displacement connectors) here. Any good installer can learn how to terminate fiber in less than 2 hours. The following picture shows a singlemode and multiomde optic cable.

singlemode and multimode optic cable

Not all fibers have infinite bandwidth. At least not the multimode fiber used in most premises networks. It’s a lot higher than copper, but as you approach gigabit speeds, you are limiting the distances available for links to 500 meters or so. Singlemode fiber, as used in telecom and CATV networks, practically has infinite bandwidth. But it uses higher cost components and can be pricey for shorter links. It’s not necessary for today’s networks but may be for the next generation. Well, fiber prices continue to fall while copper prices rise.

Know Your Application, Then Select Your Cable

Just as knowing it’s vital to select the right switches, routers and firewalls for an industrial Ethernet network, it is also vital to select the right cable. When it comes to industrial Ethernet cable, long reach and high data volumes call for fiber cable. For short runs and average data requirements, copper cable will do the job. Next consider the operating environment and mechanical devices will face to help you on a final choice. Fiberstore provides various copper cables and fiber cables, including OM3 cable, OM4 cable, Cat6A copper cable, Cat5A copper cable and other specific cables. 40G DACs and AOCs are also offered. You won;t miss it.

Choose 12-fiber or 24-fiber for 40/100G Migration

There is no doubt that 40 and 100 GbE are just around the corner, or the reality is coming. To keep up with the pace, data center managers are striving to determine which fiber optic links will support 10 GbE today while future proofing the best, most effective migration path to 40 and 100 GbE. Many network designers recommend that the use of 12-fiber multimode trunk cables can provide the best migration path to 40 and 100 GbE. While others confirm that 24-fiber trunk cables with 24-fiber MPOs on both ends is a better standards-based transition path. So which one is the most suitable solution? It all comes down to a brief comparison of these two cables over investment and reduced future operating and capital expense.

24-fiber Solution

The use of 24-fiber trunk cables between switch panels and equipment is a common-sense approach, but people may not be familiar with this optic scenario. In fact, a 24-fiber trunk cable is used to connect from the back of the switch panel to the equipment distribution area. For 10 GbE applications, each of the 24 fibers can be used to transmit 10 Gbps, for a total of 12 links. For 40 GbE applications, which requires 8 fibers (4 transmitting and 4 receiving), a 24-fiber trunk cable provides a total of three 40 GbE links. For 100 GbE, which requires 20 fibers (10 transmitting and 10 receiving), a 24-fiber trunk cable provides a single 100 GbE link as shown in Figure 1.

12-fibers

Maximum Fiber Utilization

As noted before, 40 GbE uses eight fibers of a 12-fiber MPO connector, leaving four fibers unused. When using a 12-fiber trunk cable, three 40 GbE links using three separate 12-fiber trunk cables would result in a total of 12 unused fibers, or four fibers unused for each trunk. But with the use of 24-fiber trunk cables, data center managers actually get to use all the fiber and leverage their complete investment. Running three 40 GbE links over a single 24-fiber trunk cable uses all 24 fibers of the trunk cable. Obviously, 24-fiber is more appropriate for 40/100G migration.

Increased Fiber Density

Because 24-fiber MPO connectors offer a small footprint, they can ultimately provide increased density in fiber panels at the switch location. With today’s large core switches occupying upwards of 1/3 of an entire rack, density in fiber switch panels is critical. Hydra cables feature a single 24-fiber MPO connector on one end and either 12 duplex LC connectors on the other end for 10 GbE applications, 12-fiber MPO connectors for 40 GbE or a 24-fiber MPO connector for 100 GbE. With a single 1RU fiber panel able to provide a total of 32 MPO adaptors, the density for 10 GbE applications is 384 ports in a 1RU (duplex LC connectors) and 96 40 GbE ports in a 1 RU (12-fiber MPOs). Figure 2 shows a 12-fiber MTP trunk cable with MTP/APC connector on both ends largely improves the performance for 40G/100G fiber links.

mtp-jumper-cable

Reduced Cable Congestion

Cable congestion is one of the biggest problems in the data center because it will make cable management more difficult and impede proper airflow needed to maintain efficient cooling and subsequent energy efficiency. In fact, a 24-fiber trunk cable are only appreciably larger than 12-fiber trunk cables in diameter. That means the 24-fiber trunk cables provide twice the amount of fiber in less than 21% more space. For a 40 GbE application, it takes three 12-fiber trunk cables to provide the same number of links as a single 24-fiber trunk cable—or about 1-1/2 times more pathway space.

Cost-effective Migration Path

As 24-fiber trunk cables can effectively support all three applications shown in Figure 3, there is no need to recable the pathways from the back of the switch panel to the equipment distribution area. That means that data center managers can easily migrate to higher speeds with all of that cabling remains permanent and untouched. With 24-fiber trunk cables offer guaranteed performance for 10, 40 and 100 GbE, upgrading the cabling infrastructure is as simple as upgrading the hydra cables or cassettes and patch cords to the equipment.

migration path from 10G to 40&100G

Conclusion

With guaranteed support for all three applications, the ability to use all the fiber deployed, reduced cable congestion and higher port density in fiber panels, and an easy migration scheme, 24-fiber trunk cables offers lower future capital and operating expense. Fiberstore supplies 12, 24, 48, 72, 96 and 144 fiber core constructions with OM1, OM2, OM3 or OM4 fiber trunk cable, these trunk cable assemblies are composed of high quality LSZH jacketed fiber optic cables, connecting equipment in racks to MTP/MPO backbone cables. 40G QSFP+ optical transceivers like FTL410QE2C and QSFP-40G-LR4-S are also provided. If you are interested in any of our products, please contact us directly.

Fiberstore’s 10 Gigabit Ethernet Transceivers and Cables Frequently Asked Questions

What is the difference between SFP+ and SFP?

The pinouts of SFP and SFP+ connectors are identical. However, SFP has a maximum data rate of 5Gb/s whereas SFP+ is designed for 10Gb/s. The SFP receptacles and plugs are not as well impedance matched as SFP+ receptacles and plugs. Also SFP+ cable is designed for 10Gb/s whereas SFP cable may not be able to satisfactorily transmit that rate.

What is the distance supported by the SFP+ SR transceiver?

The supported distance is up to 300 meters depending on the quality of the multimode fiber (MMF) you use. Quality of MMF is listed as OM1 (up to 33 meters), OM2 (up to 82 meters), OM3 (up to 300 meters), and OM4 (up to 400 meters). Check with the supplier for the cable distance supported. Take GP-10GSFP-1S as an example, it is Dell Force10 10GBASE-SR SFP+ covering a distance of 300m over OM3 multimode cable.

Can I use SFP+ cables in SFP ports?

Yes, SFP+ cables are compatible to SFP ports and will work fine. SFP cables are not compatible to SFP+ ports. SFP+ receptacles have a mechanical feature to prevent engaging SFP plugs.

Do Fiberstore’s SFP+ direct-attach Twinx passive cables work with Cisco or other third-party switches?

Fiberstore’s direct-attach SFP+ Twinx passive cables are fully compatible with the original brand like Cisco. For example, SFP-H10GB-CU3M is Cisco SFP+ to SFP+ passive copper cable from Fiberstore which is fully compatible with Cisco switch. The following image shows that our professional trained staff tests the compatibility and interoperability of each optics to make sure our customers to receiver the optics with superior quality.

Fiberstore test program

What are the distances supported by cables to use with the 10GBase-T ports? Does Fiberstore offer these cables?

Data centers have a large installed base of Cat 5/6/7 twisted pair cables for the last decades—initially for 1000BASE-T and now for use with 1/10GBase-T infrastructure. Fiberstore does offer these cables since they are industry standard and widely available from us in various lengths and colors. Distances supported at 10 Gbps speed:

  • CAT 6A and CAT 7 cables supporting 100 meters
  • CAT 5e and CAT 6 cables supporting 55 meters

Do the SFP+ optical transceivers support 1 GbE operation?

Yes, they support 1GbE and 10 GbE dual rates and can be configured for 1 GbE.

Will the SFP+ optical transceivers auto-negotiate between 1 GbE and 10 GbE?

Auto-negotiation is not supported between the 10 GE and 1 GE speed. The transceiver must be manually configured to operate at 1 GE speed.

How do I use the SFP+ ports for 1000BASE-T?

You need to purchase Fiberstore’s SFP+ to 1000BASE-T Media Converter. (SFP+/Copper RJ45), part number FMC-1SFP/1RJ45-GB.

Is TwinX same as Twinax?

Yes.

Does the Twinx copper cable plug directly into the NIC and the switch?

Yes, the copper cable has an SFP+ or QSFP connector on both ends of the cable that directly plugs into the corresponding ports of the switch and NIC.

Should I use optical transceivers with the SFP+ and QSFP direct-attach Twinx copper cables?

No. These are direct-attach Twinx cables and come with connectors that plug directly into the SFP+ port or the QSFP port of the switch/NIC on either end. Transceiver cannot be used.

What is the advantage of SFP+ Twinx copper cable?

It is a low-cost option for shorter distances up to 5 meters.

Is 10GBase-T same as 10GBASE-T?

Yes. 1GBase-T is shorthand for 1000BASE-T and 10GBase-T is same as 10GBASE-T; they are the twisted pair implementations of 1 GbE and 10 GbE respectively.

What are the SFP+ copper cables provided by Fiberstore?

10G SFP+ copper cable

The above chart lists detailed information about some of the 10G SFP+ cables from Fiberstore. We also offer SFP+ copper cables that are fully compatible with major brand like Cisco, Juniper, Brocade, etc. The supported distance of this cable varies from 0.5m to 7m. Users can connect our SFP+ copper cable with top-of-rack (ToR) switch to realize 10G connectivity. For more information, please contact us directly.

Upcoming 40/100G Technology

The past decades witnessed the tremendous advancement in Ethernet network transmission speeds from 10/100 base systems to 1G then 10G deployments. Today, 10G server uplinks are ubiquitous in the data center, driven by the need for higher bandwidth, 40/100G server uplinks are just around the corner. IEEE ratified 40/100G Ethernet Standard in June 2010. Since then people were hoping to embracing this new Gigabit Ethernet. However, migrating to higher data rates seems not be that easy. This article will pay special attention to those aspects that influence the migration path.

New Transceiver Interface: MPO Connector

When transition to 40/100G, parallel optics are needed to transmit and receive signals. Because for 40G, there are 4-Tx and 4-Rx fibers, each transmitting at 10G for an aggregate signal of 40G. And for 100G, there are 10-Tx and 10-Rx. As parallel optics technology requires data transmission across multiple fibers simultaneously, a multifiber (or array) connector is required. Defined by TIA-604- 5-C, Fiber Optic Connector Intermateability Standard, MPO (FOCIS-5) is an array connector that can support up to 72 optical fiber connections in a single connection and ferrule. Factory-terminated MPO solutions allow connectivity to be achieved through a simple plug and play system. And this MPO-terminated backbone/horizontal cabling is simply installed into preterminated modules, panels, or Harnesses.

40G Ethernet Solution

According to IEEE 802.3ba, 40G was designated to support high-performance computing clusters, blade servers, SANs and network-attached storage. When deploying 40G network, QSFP transceiver and a 12-fiber MPO will be utilized. Deployment of 40G over multimode fiber will be achieved with 4-Tx and 4-Rx fibers from the 12-fiber MPO. The fibers will be the outer fibers as shown in Figure 3. Each of these four “channels” will transmit 10G for the combined 40G transmission. While single-mode fiber transmission will remain duplex connectivity using course wavelength division multiplexing. Some transmission media for 40G are to be included in the following table.

40G

  • 40 GBASE-SR4 (parallel optics)

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

  • 40 GBASE-LR4 course wavelength division multiplexing (cWDM)

—10km on single-mode fiber, 4x 10G 1300 nm wavelength region like QSFP-40GE-LR4

  • 40 GBASE-CR4

—7 m over copper, 4 x 10G (twinax copper)

100G Ethernet Solution

40G is to support increasing bandwidth demand for server computing, while 100G was designated to support switching, routing and aggregation in the core network. For 100G deployments, the CXP will be the electronics interface for OM3/OM4 multimode fiber, while CFP will be the interface for single-mode fiber. For 100G transmission over multimode fiber, the optical connector interface will be the 24-fiber MPO connector that will support 10-Tx and 10-Rx channels, each transmitting at 10G. Transmission over single-mode will be achieved via wavelength division multiplexing with duplex connectivity.

100G

  • 100 GBASE-SR10 (parallel optics)

—100m on OM3 or 125m on OM4, 10G on 10 fibers per direction

  • 100 GBASE-LR4 (dWDM)

—10km on single-mode, 4 x 25G 1300 nm

  • 100 GBASE-ER4 (dWDM)

—40km on single-mode, 4 x 25G 1300 nm

  • 100 GBASE-CR10

—7 m over copper, 10 x 10G (twinax copper)

Cabling Migration From 10G to 40G to 100G in an MPO-based System

Starting with 10G, a 12-fiber MPO cable is deployed between the two 10G switches. Modules are used at the end to transition from the 12-fiber MPO to LC duplex. This enables connectivity into the switch (Figure 3).

10G over 12-Fiber MPO Cabling

For 12-fiber MPO cassette-based optical systems already installed, 40G migration is as simple as replacing the existing cassette from the patch panel housings at the equipment and cross connects with an MPO adapter panel. The use of a 12-fiber MPO jumper is needed to establish connectivity between the switches (Figure 4).

40G over 12-Fiber MPO Cabling

Future 100G networks will require a 24-fiber MPO jumper to establish a link. Systems that use 12-fiber MPO backbone cabling will need a 24-fiber to two 12-fiber MPO jumpers (Figure 5).

100G over 12-Fiber MPO Cabling

Future Proofing

As we transition to 40G and 100G, an MPO-based trunk with appropriate fiber can be installed, which will provide an easy migration path to future higher-speed technology. This article has mentioned some optical devices and cabling solutions to support 40/100G Ethernet. Fiberstore provides a large amount of 40/100G equipment like 40G QSFP+ (JG661A), 40G DAC and AOC, etc. CFP, CFP2, CFP4 and QSFP28 are also offered with very competitive prices and high quality. To best meet the needs of the future, future proofing is crucial. So if you have any requirement of our products, please send your inquiry to us.