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.

Dig Deeper Into SFP Transceivers

Small form-factor pluggable (SFP) is a prevailing type of optical transceivers in the market widely utilized for Gigabit Ethernet application. As it has the same function with GBIC but with a smaller size, SFP transceiver is also called mini-GBIC. Optical transceivers are typically designed to both transmit and receive electrical optical signals under the Multi-Source Agreement. Each SFP module can support data rates from 1Gbps to 10Gbps. And there are a number of SFP modules and network accessories available for you to select from. Which one suits you better? The following article will dig deeper into the SFP transceivers that will help decide which one will work best for you.

SFP transceivers have a variety of different transmission and receiving type, users can select the appropriate transceiver for each link, to provide the optical performance can be achieved based on the available fiber type (such as a multimode fiber or single-mode fiber). Optical SFP modules available are generally divided into the following categories. Figure 1 displays the basic components of a SFP transceiver.

 

1000BASE-LX—Specified in IEEE 802.3 Clause 38, 1000BASE-LX uses a long wavelength laser (1270-1355 nm), and a maximum RMS spectral width of 4nm. 1000BASE-LX is designed to cover a distance of up to 10 km over 10µm single-mode fiber. 1000BASE-LX can also run over all common types of multimode fiber with a maximum segment length of 550 m. For link distances greater than 300 m, the use of a special launch conditioning patch cord may be required. E1MG-LX-OM is Brocade 1000BASE-LX SFP that can work over a distance of 10km.

1000BASE-EX—1000BASE-EX is not a standard but industry accepted term for Gigabit Ethernet transmission. It is very similar to 1000BASE-LX10 but achieves longer distances up to 40 km over a pair of single-mode fibers due to higher quality optics than a LX10, running on 1310nm wavelength lasers. It is sometimes referred to as LH (Long Haul).

1000BASE-ZX—1000BASE-ZX is also a non-standard but multi-vendor term using 1,550nm wavelength to achieve distances of at least 70 kilometers over single-mode fiber. Some vendors can specify distances up to 120 kilometers over single-mode fiber. Ranges beyond 80 km are highly dependent upon the path loss of the fiber in use, specifically the attenuation figure in dB per km, the number and quality of connectors/patch panels and splices located between transceivers.

1000BASE-SX—1000BASE-SX is a Gigabit Ethernet standard for operation over multimode fiber using a 770 to 860 nm, near infrared (NIR) light wavelength for a maximum of 550m at 1.25 Gbit/s (gigabit Ethernet) or 150m at 4.25 Gbit/s (Fibre Channel). Take EX-SFP-1GE-SX as an example, it is 1000BASE-SX SFP that can support a link length of 550m over OM2 cable. Figure 2 shows that EX-SFP-1GE-SX inserts into a Juniper SRX210.

 

1000BASE-BX10—1000BASE-BX10 is capable of up to 10 km over a single strand of single-mode fiber, with a different wavelength going in each direction. The terminals on each side of the fiber are not equal, as the one transmitting downstream uses the 1490nm wavelength, and the one transmitting upstream uses the 1310nm wavelength.

1000BASE-T—It is a standard for Gigabit Ethernet copper cabling. The maximum length of 1000GBASE-T is 100 meters. 1000BASE-T must use Category 5 cable or better (including Cat 5e and Cat 6. 1000BASE-T can be used in data centers for server switching, for uplinks from desktop computer switches, or directly to the desktop for broadband applications.

1000BASE-TX—Created by the Telecommunications Industry Association (TIA), 1000BASE-TX (TIA/EIA-854) is a standard similar to 1000BASE-T that was simpler to implement. Compared with 1000BASE-T, this simplified design would have reduced the cost of the required electronics by only using two unidirectional pairs in each direction instead of 4 bidirectional. However, this solution has not been widely used largely due to the required Category 6 cabling and the rapidly falling cost of 1000BASE-T products.

Recommended Information It is known that there is no visual difference between the bare SFP modules, so how to differ them? Smart manufacturers figure a way out by marking the color of pull ring to distinguish generally. For example: black pull ring is multimode, the wavelength is 850 nm; blue is the 1310nm module; yellow is the 1550nm module; purple is the 1490nm module and so on. If you are confused with the specifications of the SFP modules, you should find a reliable vendor to help you. Fiberstore provides a variety of SFP modules including 100BASE SFP, 1000BASE SFP, BiDi SFP, CWDM/DWDM SFP, SONET/SDH SFP and 2G/4G FC SFP. Our SFP modules are fully compatible with major brand. For more information about SFP transceivers, please feel free to contact us.