SMF and MMF 40G QSFP+ Transceiver Overview

With the wide deployment of 40 Gigabit Ethernet , many companies are upgrading data center from 10G to 40G. In order to realize the migration, there are several factors that need to be considered. First, the potential for a reconfiguration of the physical layer of the network based on the reduced reach of the OM3/OM4 multimode optics from 10GBASE-SR (300/400 m) to 40GBASE-SR4 (100/150 m). Second, the existing fiber optic cabling should be upgraded based on the additional fiber count needed to support 40GBASE-SR4 parallel optics. So manufacturers produce SMF&MMF 40G QSFP+ transceiver.

Introduction to SMF & MMF 40G QSFP+ Transceiver

Generally speaking, a fiber optic transceiver may either operate on multimode fiber (MMF) or single-mode fiber (SMF). However, a SMF&MMF 40G QSFP+ transceiver can be used with both MMF and SMF without the need for any software/hardware changes to the transceiver module or any additional hardware in the network. This transceiver operates in the 1310nm band and can support transmission distance up to 150 m over OM3 or OM4 multimode fiber and up to 500 m over single-mode fiber (different vendor may have different specifications). This can be achieved by combining 150 m over OM3 or OM4 multimode fiber and up to 500 m over single-mode fiber (different vendor may have different specifications) inside the transceiver module over a single pair of multimode or single-mode fibers. Now there are two main SMF&MMF 40G QSFP+ transceiver in the market: Arista QSFP-40G-UNIV and Juniper JNP-QSFP-40G-LX4. They are used for upgrading from 10G to 40G networks over MMF and SMF without modification or expansion.

Advantages of SMF & MMF 40G QSFP+ Transceiver

The increasing needs for bandwidth drives data center migrating to 40G. Optical equipment connecting switches are needed. SMF&MMF 40G QSFP+ transceiver is designed to allow for seamless migrations from existing 10 to 40GbE networking without requiring a redesign or expansion of the fiber network. Besides, this transceiver also provides a cost-effective solution to migrate from multimode to single-mode fiber, which can support the distance up to 500 m with the single-mode fiber infrastructure. The following will talk about its advantages in detail.

• Zero-cost Cabling Migration Existing 40G transceivers for short reach, uses four independent 10G transmitters and receivers for an aggregate 40G link, which use an MPO-12 connector and require 8-fiber parallel multimode fiber (OM3 or OM4). But a SMF&MMF QSFP+ allows the same cables to be used for direct 10G connections to direct 40G connections, resulting in zero-cost cabling migration. Because it uses duplex LC connector consistent with the existing 10G connections, which commonly utilize MMF cables with duplex LC connectors.
• Increase Number of 40G Links Existing MMF 40G solutions use 8 fibers for a 40G link. Network designers have to add additional fiber to increase the number of 40G links. With SMF&MMF 40G QSFP+ transceiver, there is no need to change fiber infrastructure. It only needs to increase the number of 40G links by 4 times to expand network scale and performance.
• Migrate from Multimode to Single-mode Fiber For the future upgrading from 40G to 100G and beyond to 400G, there is a strong desire for data centers to move to single-mode fiber for cost effectiveness. Because multimode transceivers have limitations of supporting distances with ever increasing data rates, while single mode transceivers, such as the JNP-QSFP-40G-LR4 QSFP+ transceiver can support max distance of 10 km over single mode fiber cables. However, the single-mode transceivers typically cost up to 4 times more compared to multimode transceivers. As SMF&MMF QSFP+ interoperates with 10km QSFP-LR4 optics, it s a cost effective solution for SM fiber infrastructure for distances up to 500 m.
• Simplify the Data Centers The SMF&MMF 40G QSFP+ transceiver operates on both multimode and single-mode fiber without any requirement for additional hardware or software. Network designers can use SMF&MMF QSFP+ irrespective of the fiber type, which takes full advantage of the existing cabling systems, reducing the cost of deployment and of support, and simplify purchasing and deployments.

Summary

The utilization of SMF&MMF QSFP+ transceiver can help migrate from 10G to 40G without teh need to redesign or change the cable infrastructure. Besides, it can save cost and expand the infrastructure with low capital investment. It also offers a migration to single-mode fiber in data centers with a single transceiver that bridges the gap between multi-mode and single-mode optics. Fiberstore provides cost-effective SMF&MMF 40G QSFP+ transceiver for migrating to next-generation 40G data center deployments. Besides, single mode transceivers (like 40GBASE-LR4 QSFP+) and multi-mode transceivers (like Cisco QSFP-40G-CSR4) are also available for your choice.

Cabling and Transceiver Options for 10 Gigabit Ethernet

In the past few decades, the Ethernet industry has been working on providing solutions to increase the speed of Ethernet from 1 to 10 gigabits per second. For enterprise LAN applications, 10 Gigabit Ethernet enables network managers to scale their Ethernet networks from 10 Mbps to 10,000 Mbps, while leveraging their investments in Ethernet as they increase their network performance. There are various types of cables and transceivers available for making Ethernet connections at speeds of 10 Gigabit per second. This article will introduce both the copper and fiber connectivity options for 10 Gigabit Ethernet.

Transceiver Options

Standards bodies initially offered several options for the 10-Gigabit transceiver. The one that ultimately evolved as most popular in commercial data center usage was the XFP transceiver. In recent years an extension of the SFP transceiver was standardized for use with 10 Gigabit Ethernet and named SFP+. SFP+ has three outstanding advantages. First of all, it was smaller than the XFP form factor allowing for much more dense packaging of ports on (primarily) switches. Secondly, a new type of very short distance copper cable was developed which uses the same mechanical form factor as the optical transceiver and is capable of carrying 10Gbps Ethernet data. This cable type is called direct attach copper cable which will be introduced later. SFP+ has now become the predominant 10G Ethernet connector type. (The following picture shows Cisco SFP-10G-SR-X compatible 10GBASE-SR/SW SFP+ transceiver).

Fiber Cabling

Fiber cables consist of the cable itself and the connectors on the ends. There are multiple choices for cable type and for connector type. The difference in cable choices come from the distance limitations encountered with the various types of optical transmission. The commonly available types of fiber cables include: SR for connections of up to 300 m in length, LR for connections of up to 2 km in length and ER for connections of up to 10 km in length.

Copper Cabling

• 10GBASE-T For 10-Gigabit Ethernet cabling, the standards body determined that even enhanced Cat5e UTP traditional Ethernet cable would not be able to carry the signal reliably for any significant distance. So a new specification which still uses RJ45 connectors was introduced and is commonly referred to by its standards name 10GBASE-T. It calls for a 4-wire twisted pair cable with even more strinent limitations on cross-talk.
• CX4 CX4 is a cable type generally associated with an alternative networking technology called InfiniBand. CX4 cable can also be used in 10Gigabit Ethernet connections. It uses a coaxial copper cable and can support cable lengths of up to 15m.
• SFP+ As discussed above, one of the advantages of the SFP+ connector type was that a new type of very-short-distance copper cable was developed which uses the same mechanical form factor as the optical transceiver and is capable of carrying 10Gbps Ethernet data. This cable type namely SFP+ direct attach copper cable is a fixed assembly that is purchased at a given length, with the SFP+ connector modules permanently attached to each end of the cable. For instance, the following Brocade 10G-SFPP-TWX-0101 compatible 10G SFP+ direct attach copper cable is terminated with one SFP+ connector on each end of the cable. It provides high performance in 10 Gigabit Ethernet network applications, using an enhanced SFP+ connector to send 10 Gbps data through one paired transmitters and receivers over a thin twinax cable.

The deployment of 10GbE infrastructure should be much easier, with these media options in mind, coupled with your own such project considerations as cost, power consumption and distance reach. 10 Gigabit Ethernet has become the technology of choice for enterprise, metropolitan, and wide area networks. Choosing the right kind of connectivity options helps you ensure the proper and right performance of your networks.

Understanding 24-fiber MTP/MPO Connectivity

Comparison between 12-fiber and 24-fiber connectivity

In selecting the migration path from 10G to 40/100 G, there are generally two options: the 12-fiber MPO/MTP solution or 24-fiber MPO/MTP solution. A 12-fiber MPO/MTP connector is used for 40 GbE (data rate up to 40Gbps, 4 x 10 Gbps). But among the 12 fibers, only 8 optical fibers are required—4 for Tx and 4 for Rx, and each channel has a transmission rate of 10 Gbps (usually use the 4 left and 4 right optical fibers, and the inner 4 optical fibers are left unused). And for 100 GbE (data rate up to 100 Gbps, 10 x 10 Gbps or 4 x 25 Gbps), there are two solutions. One is to use two 12-fiber MPO/MTP connectors, one transmitting 10 Gbps on 10 fibers and the other receiving 10 Gbps on 10 fibers. The other is to use a 24-fiber MPO/MTP connector. In this situation, misconceptions about 24-fiber connectors and assemblies in MTP/MPO connectivity emerge.

Using 24-fiber cabling throughout an entire channel provides extra flexibility, as users can easily migrate from 10G to 40G or 100G by simply swapping out the connectivity at the end of the channel. Pre-terminated cabling using 24-fiber connectors provides double the density of 12-fiber cabling in the same footprint, reducing the cabling required, allowing for fewer cable pathways, and improving airflow in data centers.

Misconception 1

New proposed standards define 100GbE over fewer fibers, as opposed to 20 fibers. This makes 24-fiber connectors superfluous.

The current IEEE 802.3ba 100GBASE-SR10 standard defines 100GbE using 10 lanes of multimode fiber at 10 Gb/s. Progress has indeed been made in delivering 100 GbE over fewer lanes, and the IEEE 802.3bm task force is developing a new standard that would use 4 lanes of multimode fiber at 25 Gb/s per lane. This 4x25 solution would only require 8 fibers (4 transmit, 4 receive) — the same as the current 40GBASE-SR4. That means a 12-fiber MPO/MTP connector can support a single 100G channel. However, a 12-fiber connector for an 8-fiber channel is inefficient, as 4 strands in the 12-fiber connector are not used. Alternatively, by using a 24-fiber MTP connector in the horizontal cabling, it can then be converted into three 8-fiber 100G channels that run over one cable, with all 24 fibers used to support traffic.

Let's look at another example. Say you need to support twelve 100GbE channels using the 4x25 Gb/s standard. With the 12-fiber MPO/MTP connectors, you would need to install 12 connectors, or 144 fibers total, with 33% of the fiber wasted. However, when supporting the same 12 channels with 24-fiber connectors, only 4 cables would be required, using 96 fibers total, at 100% fiber utilization. The 24-fiber MPO/MTP channel solution allows the use of the ratified 100GBASE-SR10 20-fiber technology today, while at the same time maximizing the installed infrastructure investment in the event of 4x25 Gb/s ratification and ultimate implementation. Choosing a 12-fiber connector strategy simply does not accomplish this: it drives down return on investment and subsequently increases the total cost of ownership. This is the exact opposite of the design intent of a data center infrastructure system.

Misconception 2

24-fiber connectors don't perform as well as 12-fiber connectors, as higher fiber counts translate into higher insertion loss.

Insertion loss is a critical performance parameter in data center cabling deployments. Lower overall optical loss allows more margin for the network to operate, or in the case for some users, offers the option of more connections for patching locations. The IEEE 802.3ba 40/100GbE standard specifies OM3 fiber to a 100-meter distance with a 1.5 dB total connector loss budget. OM4 fiber for 40/100GbE is specified to a longer distance with a 1.0 dB total connector loss budget. For example, the Push-Pull MPO patch cable from FS.COM is manufactured using laser-optimized, 50/125, OM4 multimode cable, and supports speeds up to 100GbE. As total connector loss increates, the supportable distance at that data rate decreases. However, with the current trend of moving to distributed access/aggregation data center switch strategies such as Top of Rack (ToR), the prevalence of backbone lengths exceeding 100 meters is dramatically decreasing.

Some have mistakenly claimed that higher fiber count leads to higher loss, and one cable vendor pointed to a "typical" loss of 0.5 dB for 24-fiber connectors as evidence. In fact, the industry standard product rating for MPO/MTP connector performance of both 12-fiber and 24-fiber is 0.5 dB maximum. When using proper polishing techniques, 24-fiber MPO/MTP terminations can meet the same performance levels as 12-fiber assemblies. Improved performance can be achieved using low-loss ferrules for both 12-fiber and 24-fiber MPO/MTP connectors rated at 0.35 dB maximum.

24-fiber is the trend

24-fiber MTP/MPO solution is a simple and cost effective migration path from 10G to 40/100G Ethernet. It effectively supports all three applications—10, 40 and 100 GbE. Data center managers can easily migrate to higher speeds, with less time and complexity, as 24-fiber solution offers guaranteed performance for 10, 40 and 100G applications, upgrading the cabling infrastructure is as simple as upgrading the fan-out cables or cassettes and fiber patch cords to the equipment. FS.COM provides high quality fiber cables, such as Push-Pull MPO patch cable, Push-Pull LC cable and so on. All these fiber cables can be customized according to your special requirements.

3 Ways Third-Party Transceivers Benefit Your Data Center

Are you still spending hundreds of dollars on the expensive optical transceiver modules for your network system in the data center? In order to cut down the costs on the expensive transceiver modules, many companies are seeking for a compatible third-party transceiver to use. For example, if your network contains Juniper routers, firewalls, and switches, you might think that only Juniper SFP branded transceivers will ensure that all of your equipment is compatible and functions optimally. However, that seemingly reasonable assumption could cost your company thousands of dollars. Compared to the third-party optical transceiver produced by third-party companies, Juniper SFP transceiver comes with dramatically inflated price tags while a third-party compatible one is roughly 80 percent less expensive than Juniper branded SFP transceiver.

What Does "Third-Party" Mean?

In commerce, a "third-party" means a supplier (or service provider) who is not directly controlled by either the seller (first party) or the customer/buyer (second party) in a business transaction. For example, in the fiber optics industry, all fiber optic transceivers are defined by Multi-Source Agreement (MSA). MSAs strictly define the operating characteristics of fiber optic networking equipment, so that system vendors may implement ports in their devices that allow MSA compliant networking components produced by different manufacturers are interoperable. As long as a manufacturer complies to MSA guidelines, their transceiver modules will function and operate identically to any other manufacturer's MSA-compliant transceivers. For instance, HP BladeSystem 455883-B21 compatible 10GBASE-SR SFP+ transceiver from FS.COM will function identically to a HP 455883-B21 transceiver and will be 100% compatible with HP networking equipment.

Optical transceivers are some of the most all-around useful pieces of hardware for a network. As long as your equipment has SFP/SFP+ ports -which most do- transceivers allow you to change between a multitude of uplink types, to fit whatever wiring you have or will have in the future. They're simple, plug-and-play, and hot-swappable. Third-party optical transceivers can easily prevent thousands of dollars in new hardware costs. In spite of what's often implied by official documentation, a quality third-party optical transceiver is 100% compatible with name-brand equipment. There's simply no difference between good quality third-party transceivers and branded ones. So why choose to pay more?

Three Reasons Why Third-Party Optical Transceivers Just Make Sense

1. Low costs The lower costs of third-party optics really cannot be overstated. Depending on the model, name brands are anywhere from 50% to 1000% more expensive than third-party alternatives. For example, you can get the Cisco QSFP-40G-CSR4 compatible 40GBASE-CSR4 QSFP+ transceiver with only $110 at FS.COM which ensures the same performance with a Cisco branded QSFP-40G-CSR4 transceiver.

In many cases, a full loadout of third-party transceivers can shave so much money off of an upgrade budget to fund entirely new pieces of hardware. Or they can put a piece of equipment within range, which wouldn't have been if name-brand ports had to be purchased.

2. Full standards compliance Only a few factories in the world produce optics, and they make the transceivers for everyone. Those heavily-discounted third-party may be made in the same facilities as the official Cisco, HP, or Juniper units. And since transceivers are fully specified by internationally agreed-upon standards anyway, there's no risk of incompatibilities.

All it takes is code loaded on an EPROM -included in the transceiver- identifying it to your networking hardware and, basically, your equipment can't tell the difference.

3. Lifetime warranty Besides having much higher prices, the name-brand transceivers also tend to have fairly short warranty periods. It's generally anywhere from a couple years, down to only 90 days. While failure is fairly rare, it's unfortunate that they have such short warranty periods, especially compared to the hardware they're used in.

However, when you buy third-party optics from FS.COM, you will get a full lifetime warranty. That's how certain we are that they truly are of quality equal or better to the name-brand units. As long as your transceivers are in use, they're covered under warranty.

Conclusion

If you're still hesitant about trying a compatible SFP transceiver from a third party manufacturer, the best way to ensure that you're getting a reliable product at a good deal is to choose a vendor you trust, one with a proven track record of quality products and great customer service. Really, there's no compelling reason to over-pay for the name brand optics. Just like buying generic medications at the pharmacy, there is truly no difference aside from the name that's on the packaging.

Understanding SFP+ Transceiver Testing

Introduction to SFP+ Transceiver

In the 10 Gigabit Ethernet world, fiber optical transceivers have been developed along the way to meet the increasing usage and demand for higher-performance servers, storage and interconnects. The small form-factor pluggable plus (SFP+) can be referred to as an enhanced version of the SFP that supports data rates up to 16 Gbit/s. SFP+ supports 8Gbit/s Fiber Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors. In order to ensure the high performance of the SFP+ transceivers, one critical point is to deal with the testing issues of them. This article will first illustrate the SFP+ testing challenges in reality and then focus on one important testing measurement.

SFP+ Testing Challenges

The most obvious challenge is the increased port density and the testing time required with 48 or more ports per rack. For instance, there are 15 measurements each for the host transmitter tests, and each of those measurements using manual methods will take about three to five minutes. This means a test engineer will take more than an hour per port to finish the required tests, multiplied across the number of ports.

Another challenge is moving seamlessly from a compliance environment to a debug environment. If a measurement fails, how can the designer decide which component causes the failure and debug the issue to arrive at the root cause?

Next, most designers may confront with today relates to connectivity: how to get the signal out from the device under test (DUT) to an oscilloscope. Test fixtures are typically required but questions arise around whether the fixtures have been tested and validated against the specification.

Another challenge to prepare for is that the SFP+ specification calls out some measurements to be performed using a PRBS31 signal. Some measurements have PRBS31 as a recommended pattern. The maximum record length possible for acquisition with popular high-performance real-time oscilloscopes is 200 million samples. At a sampling rate of 50 Gsamples/s, the designer can acquire around 40 million unit intervals (UIs). At a sampling rate of 100 Gsamples/s, the instrument can acquire 20 million UIs. However, a PRBS31 pattern has more than 2 billion UIs. Thus, acquiring an entire pattern presents a challenge.

What’s more, acquiring a record length of 200 million data points demands huge processing power and time. One solution is to treat the PRBS31 waveform as an arbitrary waveform and acquire a modest record length of 2 million to 10 million UIs to recover the clock and compute the results. This provides a good tradeoff between processing power and test-result accuracy.

TWDPc Measurements

TWDPc, short for transmitter waveform distortion penalty for copper, requires a special algorithm defined by the SFP+ specification. This test is defined as a measure of the deterministic dispersion penalty due to a particular transmitter with reference to the emulated multimode fibers and a well-characterized receiver.

The TWDPc script (of 802.3aq, 10GBASE-LRM) processes a PRBS9 pattern requiring at least 16 samples per unit interval. Out of concern for the large installed base of equivalent-time oscilloscopes with a record length of around 4000 samples, the requirement for 16 samples per unit interval was relaxed to seven samples per unit interval.

The relaxation of the requirement from 16 samples per unit interval to just seven samples per unit interval causes worst-case pessimism of 0.24 dB TWDPc over 30 measurements. For DUTs that already have a high TWDPc, 0.24 dB can be the difference between a pass or a fail result.

The TWDPc measurement for SFP+ host transmitter output specifications for copper requires more than 70 Gsamples/s to capture a minimum of seven samples per UI. Real-time oscilloscopes offering higher sampling rates of 100 Gsamples/s or greater have a much higher chance of providing accurate results for TWDPc compared to scopes that only offer lower sampling-rate options.

Across the board, it is important to map the SFP+ signal’s data-transfer rate to the proper oscilloscope bandwidth requirements to ensure accuracy in measurement and margin testing. With a 10.3125-Gbyte/s data-transfer rate and minimum rise time of 34 ps, a scope with a bandwidth of 16 GHz or higher is required to meet the minimum requirements for SFP+. As noted, sampling rate is also an important consideration for the TWDPc measurement.

Summary

To overcome SFP+ transceiver testing challenges, fiber optical equipment manufacturers have developed solutions that can run through all SFP+ measurements quickly, generate reports, and allow access to a debug mode if the testing requires it. But in order to assure the high performance of the whole system, choosing reliable and cost-effective SFP+ modules is equally important. FS.COM offers a wide range of SFP+ transceivers, like SFP-10G-SR-X, SFP-10G-ER, SFP-10G-LRM, etc. Each fiber optic transceiver has been tested to ensure the customers to receive optics with superior quality.