Introduction to 10GbE/25GbE/40GbE/100GbE Fiber Optic Cabling

Technology is changing rapidly. Just when you got used to Gigabit Ethernet speeds being a fast & reliable system, someone unveiled 10GbE, 25GbE, 40GbE or even 100GbE systems a few years later. The newer and higher performing iterations are indeed the great breakthrough for telecommunication industry, but also pose difficulty in choosing network migration path—10G to 40G to 100G, or to 25G to 50G to 100G. We have described 10G, 25G, 40G and 100G Ethernet technology before, now in this blog, we’d like to introduce the four fiber optic cabling, and compare two 100G migration paths.

Cost-effective 10GbE Fiber Optic Cabling

10 Gigabit Ethernet technology defined by IEEE 802.3ae-2002 standard, is matured nowadays. Just like the “old” Gigabit Ethernet, 10Gb network can be terminated with either copper or fiber cabling. 1000BASE-T standard usually uses the Cat5e cables as the transmission media, while 10GbE bandwidth requires high grade copper cables like Cat6/Cat6a/Cat7 cables to support 10Gbps data rate. For instance, 10G SFP+ 10GBASE-T transceiver modules utilize Ethernet copper cables (Cat6a/Cat7) for a link length of 30m. SFP+ direct attach cables (DAC) and active optical cables (AOC) are also regarded as the cost-effective solutions for 10G short-reach applications. Besides 10G copper cables, there are single-mode (OS2) and multimode fiber patch cables (OM3/OM4) applied to different 10GbE IEEE standards. For the detailed information about the 10G cabling options, please see the following table.

As to the 10G fiber optic transceivers, there are a series of optical form factors including the XENPAK, X2, XFP, SFP+. The former three 10GbE optical transceivers were released earlier than smaller 10G form factor—SFP+ module. However, owing to their larger footprint, they are not successful on the 10G hardware market. Furthermore, SFP+ optics, compliant with several IEEE standards (SR, LR, LRM, ER, ZR and 10GBASE-T...) wins the heart of 10G end-users.

Singe-lane Design Makes 25GbE Shine

When 25G Ethernet was developed to support a single-lane 25Gbps standard in 2014, it was treated as the “new” 10GbE technology but delivers 2.5 times more data. Compared to 40GbE that was based on 10GbE, 25GbE with one lane obviously improves the port density and cost requirement. 25GbE network can support both copper and fiber optic cables, seen in the below table.Similar to 10GbE networks, 25G Ethernet physical interface specification supports several 25Gbps capable form factors, including CFP/CFP2/CFP4, SFP28 (1x25 Gbps) and QSFP28 (4x25 Gbps), which is also used for 100GbE. SFP28 25GBASE-SR and 25GBASE-LR SFP28 are two popular 25GbE optical transceiver modules available on the market, the former supports up to 100m link length while the latter allows a maximum transmission distance of 10 km.

The available optical switches of the market do not support direct 25GbE connections using an SFP28 direct attach copper (DAC) cable. It is recommended to use a breakout cable that allows four 25GbE ports to connect to a 100GbE QFSFP28 switch port. FS.COM SFP28 DAC cable lengths are limited to four meters (1m, 2m, 3m, 5m) for 25GbE. And if you prefer a longer length, the 25GbE active optic cable (AOC) solutions are good recommendations.

25G Optics SFP28	Type	Media/Reach
All 25G SFP28 Ports	25GBASE-SR	50µm MMF / 70m
	25GBASE-LR	9µm SMF / 10km
	25GBASE-AOC	Pre-terminated in 3, 5, 7, 10, 15, 20, 25, 30m lengths
	OM4 MMF MTP/MPO	150m
25G Copper SFP28	Type	Media/Reach
All 25G SFP28 Ports	25GBASE-CR Twinax / 'Direct Attach'	Pre-terminated in 1m, 2m, 3m, 5m lengths

Fast & Reliable 40GbE Fiber Optic Cabling

Like the 10GbE fiber optic cabling, there are several IEEE standards of 40GbE transceiver in the whole evolution. 40G QSFP+ optical transceivers are the most commonly used optics for 40G network. So how to choose fiber optic cables for 40G optical transceivers? The following table will help you out.

Besides the QSFP+ fiber transceivers and fiber optic cables, 40G DAC cables available in QSFP+ DAC cables and AOC cables enable short-reach options. For 40G cabling, QSFP+ to QSFP+ (40G to 40G) and QSFP+ to 4SFP+ (40G to 10G) breakout cables satisfy customers for various fiber types and reach requirements.

100GbE Fiber Optic Cabling For Future Proofing

With the price of 100G optics cutting down in 2017, 100GbE network is no longer out of customers’ reach. Telecom giants like Cisco, Arista, HPE launches series of 100G optical switches to meet the market demand. And for other 100G components like 100G optical transceivers, fiber patch cables, racks & enclosures, etc, those are ubiquitous on the market.

100G optical transceivers including the CFP, CFP2, CFP4, CXP and the most popular 100G QSFP28 optics in IEEE standards provide a great selection to the overall users.For 100G inter-rack connections, QSFP28 to QSF28 Direct Attach Copper (DAC) Cables and Active Optical Cables (AOC) as well as the QSFP28 to SFP28 breakout cables are the cost-effective solutions.

 

Conclusion

This article introduces 10G/40G/100G fiber optic cabling, and make a clear comparison between the two paths to 100GbE. Customers prefer 4×25Gbps for the reasons: Less parallel paths, less fibers, less optics, less everything. For those who want to upgrade from 40G to 100G, appreciate the reliable performance of 40G with the potential to run across 2 parallel 25Ghz rather than 4 required today.

Introduction to HPE 40G Optics

Recently the increasing network infrastructures are upgrading to 40GbE to ensure better performance, which greatly promote the popularity of 40G optical devices, especially the 40G optical transceivers and 40G QSFP+ cables. 40G optics, featured by its unique specification, are designed to meet different connectivity applications in data center. Telecom vendors like HPE, Cisco, Juniper, Arista are offering all types of 40G optics to meet the market needs, of which 40G optics form HPE are the commonly used products on the market. This article will have a short introduction to the HPE 40G modules and DAC cables.

Shedding Light on HPE 40G QSFP+ Modules

The 40G QSFP+ module is a compact, hot-pluggable transceiver used for data communications applications. It supports Serial Attached SCSI, 40G Ethernet, QDR (40G) and FDR (56G) Infiniband and other communications standards. Compared with SFP+ modules, QSFP+ transceiver increases the port-density of 3-4 times. The following part will mainly introduce three different types—40G LR4 QSFP+ transceiver, 40G SR4 QSFP+ transceiver and 40G CSR4 QSFP+ transceiver. Figure 1 shows a QSFP+ modules plugging into a HPE switch.

• HP 40GBASE-LR4 QSFP+ Transceiver

The 40G LR4 QSFP+ transceiver enables high-speed 4x10G operations and can be interoperability with 10GBASE-LR interfaces. Together with the LC connector, it can support an optical link length up to 10 kilometers over single-mode fiber. 40G QSFP+ cable is compliant with QSFP+ MSA and IEEE 802.3ba. In order to realize the function of transmitting 4-channel signals over single-mode fiber, this transceiver has to introduce MUX/DEMUX to multiplex/de-multiplex optical signals.

• HP 40GBASE-SR4 QSFP+ Transceiver

The 40G SR4 QSFP+ transceiver compatible with the 802.3ba 40GBASE-SR4 standard, provides a 40G optical connection using MPO/MTP fiber ribbon connectors. Unlike the 40G LR4 QSFP+ transceiver, this transceiver are used together with multimode fiber, supporting with a link length up to 100 meters on OM3 cable and 150 meters on OM4 cable. Take HPE JG325B as an example, it supports link lengths of 100m and 150m, respectively on OM3 and OM4 multimode fiber at a wavelength of 850nm. It primarily enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber connectors and can also be used in a 4x10G module for interoperability with 10GBASE-SR interfaces.

• HP 40GBASE-CSR4 QSFP+ Transceiver

40GBASE-CSR4 QSFP extends the reach of IEEE 40GBASE-SR4 interface to 300 and 400 meters on laser-optimized OM3 and OM4 multimode parallel fiber, respectively. Each 10-gigabit lane of this module is compliant to IEEE 10GBASE-SR specifications. This module can be used for native 40G optical links over 12-fiber parallel cables with MPO/MTP female connectors or in a 4x10G mode with parallel to duplex fiber breakout cables for connectivity to four 10GBASE-SR interfaces.

Features of 40G HP QSFP+ Modules

• Hot-pluggable input/output device that plugs into a 40 Gigabit Ethernet QSFP port
• High-speed electrical interface compliant to the IEEE 802.3ba standard
• Certified and tested on QSFP 40G ports for superior performance, quality, and reliability
• Digital Diagnostics Monitoring Interface

In addition, QSFP+ modules provide 40Gb/s Ethernet data rates over MMF optic cable and SMF optic cable. QSFP+ modules taking up very little space on a switch or server interface, allowing vendors to provide multiple QSFP+ ports in the same space. Besides the QSFP+ transceivers, HPE also offers QSFP+ cables for interconnection, which will be introduced in the next part.

HP 40GbE QSFP+ Cables

HPE offers a variety of 40GbE optical devices, such as QSFP to Four SFP+ copper breakout cables, QSFP to Four SFP+ active optical breakout cables, QSFP to QSFP active optical cables, etc. Each has its unique characteristics. Take HPE QSFP+ breakout cable as an example, compatible HPE JG330A (QSFP+ to 4SFP+ Passive Copper Cable) is very suitable for short distances and offer a very cost-effective way to establish a 40-gigabit link between QSFP port and SFP+ port of HPE switches within racks and across adjacent racks.

HPE QSFP+ to QSFP+ active optical cables are suitable for 40G Ethernet. And there are two common active optical cables available on the market—QSFP to 4 SFP+ breakout AOC and QSFP to QSFP AOC (see in the above image). QSFP to 4 SFP+ breakout AOC is a 4×10 Gb/s parallel active optical cable that transmits four separate streams of 10 Gb/s data over ribbon cables in a point-to-multipoint configuration. This cable contains a QSFP+ module on one end and four separate SFP+ modules at the other ends. The latter is a 40 Gb/s parallel active optical cable which transmits error-free parallel 4×10 Gb/s data over multimode fiber (MMF) ribbon cables.

Choose Compatible HPE Transceiver Modules

The first factor that forces people to choose third-party transceiver modules other than original modules is budget. Because the price of the original products is usually three or four times higher than 3-rd party devices. Designers can’t afford it. In addition, the third-party transceiver modules offered by reliable vendors are guaranteed to be well-tested and fully compatible with the major brand. It is feasible to buy compatible HPE transceivers from reliable OEM vendors. For example, FS.COM is devoted to design, manufacture, and sell a broad portfolio of optical products, including compatible HPE 40G QSFP+ transceivers. We supply high quality QSFP+ transceivers which are used primarily in switches, routers, and data center equipment.

Multi-mode or Single-mode Optics for 40GbE Network

To back the changing and fast-growing bandwidth demands of data center, in 2010, the IEEE ratified 40 Gigabit and 100 Gigabit standards, known as IEEE 802.3ba. 40G and 100G Ethernet can be deployed using the same cabling systems today. Both single-mode (SMF) and multi-mode (OM3,OM4) were approved to be utilized in the standard. Multi-mode deploys parallel optics with MPO/MTP interconnects while single-mode fiber will employ serial transmission and use LC or SC connectors. Which cabling options designers should choose for their infrastructure. This article today will provide some practical suggestions to help you make a wise selection. Table 1 shows the comparison between SMF and MMF for 40/100 GbE Implementations.

40GbE Over Multi-mode Fiber
40GbE and 100GbE over multi-mode optics use parallel optics at 10Gbps lasers, simultaneously transmitting across multiple fiber strands to achieve high data rates. Because of the multi-lane nature of these optics, 40GbE multi-mode optics use a different style of fiber cabling, known as MPO or MTP cabling. An MPO/MTP cable presents 12 separate strands of multi-mode fiber in a single ribbon cable. Just as 10GbE optics over multi-mode fiber, an OM3 or OM4 grade MMF is needed to cover longer distances for 40G network.

OM3 and OM4 MMF are laser-optimized fiber with a core size of 50/125 micron. These 50-micron fibers are optimized for the 850nm transmission of VCSEL-based transceivers. These two fibers have different bandwidths, which results in different achievable lengths for the same transceivers. OM4 fibers, according to the TIA-492AAAD, have higher network reliability and increased design flexibility allowing links with a reach of 150 meters. The IEEE 802.3ba standard specified OM3 fiber with a maximum reach of 100 meters. Take Cisco QSFP-40G-SR4 QSFP+ as an example, it can support a distance of 100m and 150m over OM3 and OM4, respectively. The following image shows a 40G-SR4 and 40GBASE-LR4 QSFP+.

Since we can deploy both OM3 and OM4 MMF for our 40G infrastructure, which one is more suitable? In fact, some senior engineers say that installing either OM3 or OM4 cabling in the data center largely depend on length requirements. They determined that OM4 fiber would substantially extend the reach of next generation networking within the data center and it is able to achieve this greater reach because of its greater EMB over OM3 fiber. OM4 optical fiber enables 40/100G Ethernet to reach an additional 60% of the links in the core-to-distribution and in the access-to-distribution channels when compared to OM3. This should lead to faster market acceptance of 40G/100G Ethernet and OM4 fiber.

40GbE Over Single-mode Fiber
40GBase-LR4 optics use the same multi-lane technology as SR4 optics using four strands for transmit and four strands for receive. But with one exception. Instead of using a single fiber strand for each lane, WDM technology is used to multiplex all four transmit lanes onto one strand of fiber and all four receive lanes onto another single strand of fiber, allowing any existing single-mode fiber installation to be used. Because of this, standard LC (for QSFP modules) or SC (for CFP modules) connections are used, allowing for an easy upgrade from a 10GbE connection. The channel cost for 40GBASE-LR4 is much higher than SR4 optics, which is the main factor that limits its popularity. However, 40GBASE-LR4 like Cisco QSFP-40G-LR4 can reach up to 10km.

Conclusion
After going through this article, do you have any idea of choosing which cabling for your 40G network. If you have tight budget and cover a short transmission distance, laser-optimized multi-mode cabling would be the prefect choice. But if you prefer to deploy a high-density long-reach network, single-mode cabling will suit you better. Fiberstore manufactures a large variety of 40G transceivers and cables. You can find what you need here. Please contact us if you are interested.

Copper Cabling for 40G Data Center

A heated debate over whether fiber will take place of copper in the near future has caught people’s attention lately. Five to seven years ago, fiber was considerably more expensive than copper and, as such, was used sparingly. As fiber price has dropped dramatically and our bandwidth needs have grown, data centers have started to use more fibers all the way to their infrastructure. Under this circumstance, people wonder that copper cabling may soon be out of the stage of telecom industry. But the truth is that there is a still a place for copper cabling in the data center, even in 40G data center.

Deploying Copper Cabling in 40G Data Center
The biggest market for 40G Ethernet (40GbE) is in data center for interconnection links with servers and storage area networks. There are lots of 40GbE devices that can be used in 40G data centers. 40G direct attach copper cable (DAC), especially passive copper cables (PCC) is one of those devices that can support 40GbE networking. PCC is the preferred alternative for short-reaches in the data center and as such, that won’t necessarily change as speeds increase. Copper cable assemblies are significantly more affordable than fiber, and many twinaxial cables available on the market today can support 40G for reaches of seven meters or less.

40G QSFP+ Passive Copper Cable
QSFP+ (Quad Small Form-factor Pluggable Plus) copper cable assemblies were developed for high-density applications, offering a cost-effective, and low-power option for high speed data center interconnects up to 10 meters. 40GbE passive copper cables provide robust connections for leading edge 40G systems and have extremely low power consumption which improves data center power consumption and thermal efficiency which are ideal for 40G LAN, HPC and SAN applications. QSFP+ to QSFP+ passive copper cable and QSFP+ to 4SFP+ passive breakout copper cable are the two common types of QSFP+ cables that will be introduced in the following picture. Let’s take QSFP-H40G-CU1M as an example, it is compatible Cisco QSFP+ to QSFP+ passive copper cable that is suitable for very short distances of 1m and offer a very cost-effective way to establish a 40-gigabit link between QSFP ports of Cisco switches.

Copper Cabling in 40G Data Center—Pros and Cons
One important thing to note is why the feasibility of using twisted-pair-copper cabling (with RJ-45 connectors) to support 40G Ethernet is so critical to the overall market. RJ-45 connector is with no double one of the most common connector types used in data networks. As the market continues to grow from 1G to 10G, the backward compatibility of this technology will continue to be of extreme importance as work continues towards 40G. This will allow data center operators to evolve their networks based on changing requirements and do so with the least amount of disruption and cost to their networks. In addition, twisted-pair-copper cabling has proven to be an extremely cost-effective solution and designers, installers, and customers have a lot of experience and confidence in copper-based networks. While the eventual deployment of 40G-based copper solutions is still a few years out, this technology will allow organizations to think about how they are deploying copper based solutions today with an eye to the future. Doing so correctly will help ensure infrastructure costs are well managed from both a product and support standpoint.

The problem of standard twinaxial cables is not their performance as much as their tendency to be stiff and bulky, thus consuming precious rack space and blocking critical airflow. The current copper solution for 40G Ethernet limits the architectures one can deploy. 40G Ethernet QSFP+ DAC cable assemblies have a reach of 5 to 7 meters. Thus QSFP+ DAC cable (or QSFP+ breakout cable) assemblies cannot be used for most end-of-row (EoR) implementations or other architectures. What’s worse, DAC cable assemblies are a point-to-point solution and therefore cannot support a structured cabling design. Designers must be careful not to bend the cables too much because the cable’s shielding and overwrap materials can distort the precise cable geometry needed to maintain impedance control, which can degrade signal performance. Moreover, the wrapped shield, with repeated breaks in the shield along the cable length, can produce an unwanted resonance effect, evident at certain frequencies.

Summary
Will copper be completely replaced by fiber in the near future? The answer is yes or no, we have no clue. But one thing is for sure that copper cabling continues to strive to achieve the quality and speeds that fiber can handily provides, while fiber will develop itself to be more competitive among designers. It is the good news for subscribers. Fiberstore is committed to provide first-class services and high quality products for users. If you have any question about today’s topic, please leave your messages to us.