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.

10GBASE-T – Will It be the Best Media Options for 10G Data Center?

Ratified in 2006, 10GBASE-T is the standard to provide 10Gbqs connections over balanced twisted-pair copper, including Category 6A unshielded and shielded cabling. It provides great flexibility in network design due to its 100-meter reach capability. An immediate use for 10GBASE-T is to build the data center access-layer network that connects servers to access switches. But is it the best options for 10G data center? Understanding this requires an examination of the pros and cons of current 10GbE media options.

10GBASE-CX4
10GBASE-CX4 was the first favorite for 10GbE deployments, however its adoption was limited by the bulky and expensive cables, and its reach is limited to 15 meters. The large size of the CX4 connector prohibited higher switch densities required for large scale deployment. Larger diameter cables like 10GBASE-CX4 are purchased in fixed lengths resulting in challenges to manage cable slack. As a result, pathways and spaces may not be sufficient to handle this larger cable.

SFP+ 
SFP+’s support for both fiber optic cables and DAC which makes it a better solution than CX4. SFP+ is commonly used for 10G today, but it has limitations that will prevent itself from moving to every server. The following image shows a SFP+ nodule, SFP+ DAC cable and a 10GBASE-T SFP+ port media converter.

10GBASE-SR—10GBASE-SR (SFP+ fiber) fiber is great for its low latency and longer distance (up to 300 meters), but it is expensive. SFP+ fiber offers low power consumption, but the cost of laying fiber networking everywhere in the data center is prohibitive. The SFP+ fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is much more expensive. In addition, replacing a copper connection that is readily available in a server to fiber creates the need to purchase not only the fiber switch port, but also a fiber NIC for the server. EX-SFP-10GE-SR is compatible Juniper SFP+ transceiver that requires a OM3 cable to realize its 10G connectivity, which is an indispensable component for a 10G network.

10GBASE-SFP+ DAC—DAC is a lower cost alternative to fiber, but it can only reach 7 meters and it is not backward-compatible with existing GbE switches. Take MA-CBL-TA-1M as an example, it is designed to cover a distance of 1m for 10G connectivity. The DAC cables are much more expensive than structured copper channels, and cannot be field terminated. This makes DAC more expensive than 10GBASE-T. The adoption rate of DAC will be low since it does not have the flexibility and reach of 10GBASE-T.

10GBASE-T
The major benefit of 10GBASE-T is that it offers the most flexibility, the lowest cost media, and is backward-compatible with existing 1GbE networks. Like all BASE-T implementations, 10GBASE-T covers a lengths up to 100 meters, which gives network designers a far greater level of flexibility in connecting devices in the data center and the most flexibility in server placement since it will work with existing structured cabling systems. For higher grade cabling plants (category 6A and above), 10GBASE-T operates in low power mode on channels under 30 m. This means a further power savings per port over the longer 100m mode. And because 10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in existing 1GbE switch infrastructures in data centers that are cabled with CAT6 and CAT6A (or above) cabling, enabling network designers to keep costs down while offering an easy migration path to 10GbE.

One challenge with 10GBASE-T is that the early physical layer interface chips (PHYs) consumed too much power for widespread adoption. But there comes a good news with 10GBASE-T is that the PHYs benefit greatly from the latest manufacturing processes. The newer process technologies will reduce both the power and cost of the latest 10GBASE-T PHYs. The latest 10GBASE-T adapters require only 10 W per port. Further improvements will reduce power even more. In 2011, power dropped below 6 W per port, making 10GBASE-T suitable for motherboard integration and high-density switches.

Conclusion
Of all the media options offered above, 10GBASE-T breaks through important cost and power consumption barriers in 10GbE deployment as well as its backwards compatibility with 1GbE networks. Deployment on 10GBASE-T will simplify data center infrastructures, making it easier to manage server connectivity while delivering the bandwidth needed for heavily virtualized servers and I/O-intensive applications. I must say, 10GBASE-T will be the best option for 10GbE data center cabling in the near future.

Laser-optimized Multimode Fiber – OM3 and OM4

How do I determine the type of fiber needed for my campus backbone? This is the question routinely asked by network designers. I must say, with many cabling options available in the market, it is a huge project to deploy a Gigabit Ethernet network—10GbE or 40/100GbE. As system engineers should not only decide which fiber type and the cabling infrastructure is perfect for their network, but the fiber counts. This article will briefly analyze the benefits of using laser-optimized 50µm multimode fiber in a Gigabit Ethernet application.

50µm Multimode Fibers Were Introduced 
Before the advent of Gigabit Ethernet, choosing fiber type in a network design was quite easy. Standard 62.5µm multimode fiber (OM1) was used for any application up to 2000 m and network speeds up to 622 Mbps and single-mode fiber was used for anything else. But Gigabit and 10GbE changed these rules. Laser-optimized 50µm multimode fiber (like OM3 and OM4) was developed with increased bandwidth performance for 10GbE, and the fiber performance was included in the ANSI/TIA-568 Standard. Figure 1 provides a vivid impression on 50µm and 62.5µm multimode fiber.

Why Consider 50 µm Over 62.5 µm?
The major difference between 50µm and 62.5µm multimode fiber is the bandwidth. 50µm fiber is specifically designed to produce higher bandwidth values than 62.5µm at 850 nm, which enables the fiber to be used with lower cost 850nm VCSEL transmitters. Standard 50µm fiber has three times the bandwidth of standard 62.5µm fiber in the short wavelength operating window while some of the never laser-based 50µm fiber designs have 10-20 times the bandwidth of standard 62.5µm fiber (see in Figure 2). The most commonly used 50µm fibers on the market for Gigabit Ethernet is OM3 and OM4.

OM3 and OM4 Fibers
OM3 and OM4 fibers are essential components to the success of 10G optical connectivity, which are optimized for laser-based 850nm operation and have a minimum 2000 MHz•km and 4700 MHz•km effective modal bandwidth, respectively. 10G operation is supported on OM3 to 300 m and OM4 to 550 m compared to 100 m with CAT 6A copper cable. The laser-optimized fibers provide a migration path for supporting even higher data rates such as 16G and 32G Fibre Channel and 40/100G Ethernet where CAT 6/6A has no migration beyond 10G. OM3/OM4 laser-optimized 50µm multimode fiber for 10G optical connectivity in data center enables better transmission distance and performance when comparing with OM1 and OM2 fibers. For example, GP-10GSFP-1S is compatible Dell Force10 10GBASE-SR SFP+ transceiver. It required an OM3 cable to realize the link length of 300m.

As increased bandwidth requirements are called out in new installations, which have dictated a need to transition from cost-effective multimode systems to more costly single-mode systems to solve the problem of limited transmission distance in the existing infrastructure. However, compared with the expensive single-mode cabling, OM4 effectively provides an additional layer of performance that supports these applications at longer distances, thereby limiting the number of installations that truly require OS2 single-mode fiber. OM4 can even provide a minimum reach of 125m over multimode fiber within the 40 and 100GbE standards. For example, FTL410QE2C (compatible Finisar 40GBASE-SR4 QSFP+) covers a distance of 150m over OM4 cable.

Conclusion
When determining fiber types for a network application, a couple of key points should be drawn to help make the best decision. First, use the standards of each technology, do some analysis, understand the physical topology and the logical topology, then examine where you can save money. Last but not least, for distances less than 550 m, a laser-optimized multimode fiber may yield a price savings compared to a single-mode solution. Fiberstore provides a full range of multimode fibers including OM1, OM2, OM3 and OM4 multimode fibers. We offer these cables at a minimum price but with high quality. If you have any requirement of our products, please contact us directly.