Antonio Perez

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**Small Form-factor Pluggable**

Are all transceivers used to connect switches or other network equipment to **copper** or **fiber optic** cables? They are most commonly used to add fiber optic ports. Selecting the right connector is essential to build a network that functions correctly at an efficient price point. There are five form factors: **SFP**, **SFP+**, **SFP28**, **QSFP+**, and **QSFP28**. They are different optical transceiver types, but all are hot-pluggable network interface modules that connect a network switch and other networking devices (such as a server or media converter) for data transmission. Which SFP transceiver you choose depends on the cable type, application, optical range required for your network, and desired data transfer rate. They are substantially more popular than the rest of the fiber connectivity world.

Then, what is the difference between SFP vs. SFP+, SFP28 vs. SFP+, QSFP vs. QSFP28? Is QSFP28 compatible with QSFP+? Can I use SFP28 transceivers in SFP+ ports? How to choose between these five form factors? This article will explain.

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[[networking:fiber_optics|]]

[[networking:optical_fiber_fundamentals_fibers|networking:optical_fiber_fundamentals_fibers]]
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^  Comparison of SFP types  ^^^^^^^^
^Name ^Nominal speed ^Lanes ^Standard ^Introduced ^Backward compatible ^PHY interface ^Connector ^
|SFP|100 Mbit/s|1|SFF INF-8074i|2001-05-01|none|MII|LC, RJ45|
|SFP|1 Gbit/s|1|SFF INF-8074i|2001-05-01|100 Mbit/s SFP|SGMII|LC, RJ45|
|cSFP|1 Gbit/s|2| | | | |LC|
|SFP+|10 Gbit/s|1|SFF SFF-8431 4.1|2009-07-06|SFP|XGMII|LC, RJ45|
|SFP28|25 Gbit/s|1|SFF SFF-8402|2014-09-13|SFP, SFP+| |LC|
|SFP56|50 Gbit/s|1| | |SFP, SFP+, SFP28| |LC|
|SFP-DD| 100 Gbit/s|2|SFP-DD MSA| 2018-01-26|SFP, SFP+, SFP28, SFP56| |LC|
|SFP112|100 Gbit/s|1|SFP-DD MSA| 2018-01-26|SFP, SFP+, SFP28, SFP56| |LC|
|SFP-DD112|200 Gbit/s|2|SFP-DD MSA|2018-01-26|SFP, SFP+, SFP28, SFP56, SFP-DD, SFP112| |LC|
^  QSFP types  ^^^^^^^^
|QSFP|4 Gbit/s|4|SFF INF-8438|2006-11-01|none|GMII| |	
|QSFP+|40 Gbit/s|4|SFF SFF-8436|2012-04-01|none|XGMII|LC, MTP/MPO|
|QSFP28|50 Gbit/s|2|SFF SFF-8665|2014-09-13|QSFP+| |LC|
|QSFP28|100 Gbit/s|4|SFF SFF-8665|2014-09-13|QSFP+| |LC, MTP/MPO-12|
|QSFP56|200 Gbit/s|4|SFF SFF-8665|2015-06-29|QSFP+, QSFP28| |LC, MTP/MPO-12|
|QSFP112|400 Gbit/s|4|SFF SFF-8665|2015-06-29|QSFP+, QSFP28, QSFP56| |LC, MTP/MPO-12|
|QSFP-DD|400 Gbit/s|8|SFF INF-8628|2016-06-27|QSFP+, QSFP28,[18] QSFP56| |LC, MTP/MPO-16|

  Note that the QSFP/QSFP+/QSFP28/QSFP56 are designed to be electrically backward compatible 
  with SFP/SFP+/SFP28 or SFP56 respectively. Using a simple adapter or a special direct 
  attached cable it is possible to connect those interfaces together using just one lane 
  instead of four provided by the QSFP/QSFP+/QSFP28/QSFP56 form factor. The same applies to the 
  QSFP-DD form factor with 8 lanes which can work downgraded to 4/2/1 lanes.


__**[[https://en.wikipedia.org/wiki/Small_Form-factor_Pluggable|Color coding of SFP]]**__

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**Introduction on the Types of Transceivers**

Before figuring out the difference in **SFP** vs **SFP+**, **SFP28** vs **SFP+**, or **QSFP** vs **QSFP28**, it’s necessary to know what **SFP**, **SFP+**, **SFP28**, **QSFP+**, **QSFP28**, **QSFP56**, **QSFP-DD** and **OSFP** are.

**-  SFP: 100 Mbit/s and 1 Gbit/s** 

**SFP (small form-factor pluggable)** , also know as **mini-gbic (gigabit interface converter)**. An SFP module is simply a small modular transceiver that plugs into an SFP port on a network switch or server. SFP module has replaced the GBIC module in most applications because of its small size, allowing it to be used in tight networking spaces to provide fast communication between switches and important networking components. And, SFP module is hot-pluggable, which makes it easy to adjust existing networks without having to redesign the entire cable infrastructure. Meanwhile, SFP is a popular industry format supported by many network component vendors.

**-  SFP+: 10 Gbit/s**

**SFP+ (small form-factor pluggable plus)** **is an enhanced version of the SFP**. //**It supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2**//. //SFP+ also introduces direct attach for linking two SFP+ ports without additional fiber transceivers, including DAC (direct attach cable) and AOC (active optical cable)//, which are quite brilliant solutions for the short-distance direct connection between two adjacent network switches. The applications have expanded to include SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G Fibre Channel, and the emerging 32G Fibre Channel application.

**-  SFP28: 25 Gbit/s** 

**SFP28 (small form-factor pluggable 28)** **is an enhanced version of SFP+**, which complies with multiple standards and specifications such as IEEE802.3, SFF-8472, SFF-8402, SFF-8432 and SFF-8431. SFP28 has the same common form factor as the SFP+, but **supports 25Gb/s over a single lane**. **SFP28 provides a new way for networking upgrade: 10G-25G-40G-100G**, which is an energy-efficient solution to meet the growing demands of next-generation data center networks.


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**-  QSFP/QSFP+: 40 Gbit/s**

**QSFP+ (Quad Small Form-Factor Pluggable Plus)** **is an evolution of QSFP (quad small form-factor pluggable)**. //QSFP can carry 4 channels simultaneously and each channel can handle 1 Gbit/s data rate- hence the name Quad SFP. Unlike QSFP, QSFP+ supports 4x 10 Gbit/s channels.// And the 4 channels can be combined into a single 40 Gigabit Ethernet link. The QSFP+ transceiver can replace 4 standard SFP+ transceivers, resulting in greater port density and overall system cost savings over traditional SFP+ products. Nowadays, QSFP+ gradually replace QSFP and is widely used by people as it can provide higher bandwidth.

**-  QSFP28: 100 Gbit/s**

**QSFP+ is an evolution of QSFP (quad small form-factor pluggable)**. //QSFP can carry 4 channels simultaneously and each channel can handle 1 Gbit/s data rate - hence the name Quad SFP. Unlike QSFP, QSFP+ supports 4x 10 Gbit/s channels. And the 4 channels can be combined into a single 40 Gigabit Ethernet link//. **The QSFP+ transceiver can replace 4 standard SFP+ transceivers**, resulting in greater port density and overall system cost savings over traditional SFP+ products.

**-  QSFP56: 200 Gbit/s**

**QSFP56 is designed to carry 200 Gigabit Ethernet**, **HDR InfiniBand, or 64G Fibre Channel**. The biggest enhancement is that QSFP56 uses four-level pulse-amplitude modulation (PAM-4) instead of non-return-to-zero (NRZ). It uses the same physical specifications as QSFP28 (SFF-8665), with electrical specifications from SFF-8024 and revision 2.10a of SFF-8636. Sometimes this transceiver type is referred to as "**200G QSFP**" for sake of simplicity.


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{{ :networking:sfp13.png?600 |}}

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**-  SFP-DD: 200 Gbit/s and 400 Gbit/s**

**The small form-factor pluggable double density (SFP-DD) multi source agreement is a standard published in 2019 for doubling port density**. According to the SFP-DD MSA website: "//Network equipment based on the SFP-DD will support legacy SFP modules and cables, and new double density products.//" SFP-DD uses eight lanes to transmit.

**-  QSFP-DD: 400 Gbit/s and 800 Gbit/s**

**-  QSFP-DD (also called QSFP56-DD) stands for Quad Small Form Factor Pluggable Double Density, which is fully compliant with IEEE802.3bs and QSFP-DD MSA standards**. //**It supports 400Gb/s (8x50G) or reach up to 800Gb/s**//. As the smallest form factor for 400G transceivers, QSFP-DD is widely used by people as it can provide higher bandwidth.

**-  OSFP: 400 Gbit/s and 800 Gbit/s**

__**OSFP is a new pluggable form factor with eight high speed electrical lanes that will initially support 400Gb/s (8x50G) or reach up to 800Gb/s**__. The width, length and thickness of **QSFP-DD are 18.35mm, 89.4mm and 8.5mm**, while those of **OSFP are 22.58mm, 107.8mm and 13.0mm**. It is obvious that the OSFP form factor is slightly wider and deeper than the QSFP-DD, but it still supports 36 OSFP ports per 1U front panel, enabling 14.4Tb/s per 1U.


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__**Comparisons**__

After figuring out what **SFP/SFP+/SFP28/QSFP+/QSFP28/QSFP56/QSFP-DD/OSFP** are, the following part will give detailed comparisons of **SFP vs SFP+**, **SFP28 vs SFP+**, **QSFP vs QSFP28** and **SFP28 vs QSFP28**.

**-  SFP vs SFP+**: Same Size with Different Speed and Compatibility

Simple to understand, SFP+ is an updated vision of SFP, both are virtually identical in size and appearance. SFP usually support 1.25Gbit/s to 4.25 Gbit/s while SFP+ supports data rates **up to 10 Gbit/s**. When it comes to SFP vs SFP+, they have the same size and appearance, but in a different standard which SFP is based on IEEE802.3 and SFF-8472. Besides, they comply with different specifications. SFP is based on SFF-8472 protocol, and SFP+ conforms to SFF-8431 and SFF-8432. And in terms of SFP vs SFP+ compatibility, SFP+ ports often accept SFP optics but at a reduced speed of 1 Gbit/s. And SFP+ transceiver can not be plugged into an SFP port, otherwise, the product or port may be damaged.

**-  QSFP+ vs SFP+**: Different Size and Different Speed

The primary difference between QSFP and SFP is the quad form. QSFP+ is an evolution of QSFP to support four 10 Gbit/s channels carrying 10-Gigabit Ethernet, 10G Fiber Channel, or InfiniBand, which allows for 4x 10G cables and stackable networking designs that achieve better throughput.

**-  SFP+ vs SFP28**：Same Structure and Interface Standard

SFP28 and SFP have the same structure definition and interface standard, but the rate of SFP28 reaches 25Gbps, and the transmission efficiency is 2.5 times higher than that of SFP+. At present, the price of 40G optical transceiver modules and 100G optical transceiver modules is too high, and the power consumption is too large, and the speed of 10G optical transceiver modules cannot meet the needs of the network, so the 25G SFP28 optical transceiver modules just makes up for the shortcomings between the three. At the same time, in 5G communications, SFP28 transceiver modules will be widely used in fronthaul networks.

**-  QSFP28 vs SFP+**: Different sizes and working principles

SFP+ and QSFP28 transceivers actually adopt different sizes and working principles. SFP+ supports only one channel with 10 Gbit/s, while QSFP28 supports 4 separate lanes, and each is 25 Gbit/s.

**-  SFP28 vs QSFP28**: Work on Different Principles

Though there is a number “28” in their names, SFP28 and QSFP28 transceiver actually adopt different sizes and working principles. SFP28 supports only one channel with 25 Gbit/s, while QSFP28 supports 4 separate lanes, and each is 25 Gbit/s. Both of them can be used in 100G networks, but the SFP28 is applied in the form of QSFP28 to SFP28 breakout cables. The following shows a direct connection for 100G QSFP28 to 4x SFP28 DAC.

**-  QSFP-DD vs QSFP28**: Different Structure, Different rates and Different Protocol Standards

Even thougth the QSFP-DD has the same width, length, and depth as the QSFP28 with 18.35mm, 89.4mm and 8.5mm, while QSFP-DD module has an 8-lane electrical interface instead of a 4-lane and the ASIC ports of the QSFP-DD are doubled to accommodate prevailing interfaces such as CAUI-4. Therefore, the mechanical interface of QSFP-DD on the host board is slightly deeper than that of the other QSFP system transceivers to accommodate the extra row of contacts.
The QSFP-DD modules can support 400Gbps while QSFP28 can only reach 100Gbps. QSFP-DD is fully compliant with IEEE802.3bs and QSFP-DD MSA standards and the data rate of each channel can reach 25Gb/s through NRZ modulation technology to realize 200G network transmission. Also, the data rate of each channel can reach 50Gb/s by the PAM4 modulation technology, achieving 400G network transmission.

**-  QSFP-DD vs QSFP56**: Different Bandwidth & Application

QSFP-DD and QSFP56 belong to the QSFP form factor, but QSFP-DD modules can support 400Gbps while QSFP56 can only reach 200Gbps. Therefore, QSFP-DD connectors are used in 400G optical modules, DACs and AOCs, and applied for the 400G data center interconnections. And QSFP56 modules and DAC/AOC are used for 200G networks interconnection.


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**Conclusion**

**SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28 vs QSFP56 vs QSFP-DD**, all their differences in the various types of transceivers have been stated clearly in this article. Though some of them share the same design, they are designed for different data rates. And from the comparisons, it’s clear that the main driving force behind the evolution of optical transceivers is the need to achieve higher bandwidth rates with smaller form-factor. We believe that the rapid development of QSFP-DD will greatly benefit on the whole optical interconnect and communication industry. Let’s wait and see what will happen in the future.


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**A Guide to 100G Transceiver QSFP28, SFP56-DD, DSFP, SFP-DD, SFP-DD112 Name and Specs**

Confused by the name of 100G transceiver optics and cables?

The names I usually use for communication are vendor-specific dialects. It's a common story that different interpretations are commonplace next door.

The development trend of optical modules is higher speed, smaller packages and lower power consumption. As 100G, 200G, 400G and even 800G high-speed optical transceivers are wided used in data center interconnects and other fiber communication applications. Could 100G optical modules with smaller package sizes be developed to increase panel bandwidth density? It has become a common topic for system manufacturers and optical module manufacturers to discuss. 100G optical modules are mainly four channel 100G QSFP28 optical modules or single lambda 100G QSFP28 optical modules. Similar to the 100G QSFP28 single lambda optical transceivers, the SFP-DD also uses the single channel optical signal, PAM4 technology, to achieve 100G single channel optical signal transmission. The large-scale application of the SFP-DD can achieve interoperability with the current 100G QSFP28 single channel optical module and switch in the future. This forward compatible type is very conducive to network upgrading.

  * QSFP28 = Quad Small Form Pluggable
  * DSFP= Dual Small Form Factor Pluggable
  * SFP-DD = SFP Double Densty (Small Form Factor Double Densty)
  * SFP112 = Small Form Factor 112


** QSFP28**

{{ :networking:sfp6.jpg?500 |}}

The **QSFP28 is a Quad (4-channel)** small form factor hot pluggable fibre optical transceiver used for 100 Gigabit Ethernet (100GbE) data communications applications. The QSFP28 integrates 4 transmit and 4 receiver channels. The number 28 means each lane carries up to 28G data rate. QSFP28 supports 4x25G breakout connection, 2x50G breakout, or 1x100G depending on the type of QSFP28 transceiver used. The 100G QSFP28 Single Lambda optical transceivers convert four 25G electrical signals into a single-wave 100G PAM4 optical signal for data transmission by using a DSP. The optical transmitting and receiving units are reduced from four to one, effectively reducing the internal optical complexity of the optical module.

**DSFP**

Based on the trend of high throughput and large bandwidth in data center, server NICs and access switches are evolving to next-generation 100G interfaces. The biggest difference between the next-generation 100G interface and the QSFP28 interface at this stage is in the size. There are three interface standards for the 100G interface: DSFP, SFP-DD and SFP112. These standards have in common is the small mechanical size. Having the same size with SFP series transceiver, they can support 48*100G under the 1U switch panel to connect servers. Compared with SFP28 interface, the port density is increased by 4 times, greatly reducing the cost of equipment, operation and maintenance.
DSFP is similar to SFP-DD in that it has two electrical channels, each running up to 56 Gbps using NRZ and up to 112 Gbps using PAM4. Their main difference is in the number of pins: SFP-DD doubles the original SFP pins and has two rows of connecting fingers (20 pins to 40 pins); DSFP mainly follows the SFP pins but adds two pins on the basis of SFP.

**SFP-DD VS SFP112 VS SFP-DD 112**

  * SFP-DD supports up to 100 Gb/s in aggregate over a 2 x 50Gb/s electrical interface.
  * SFP112 supports 100 Gb/s over single electrical lane.
  * SFP-DD112 supports up to 200 Gb/s in aggregate over a 2 x 100 Gb/s electrical interface.

The cage and connector design provides backwards compatibility to SFP+/SFP28 modules which can be inserted into an SFP-DD/SFP-DD112 cage and connector using 1 of the electrical channels.

SFP112 cage and connectors are compatible with SFP+/SFP28 modules. Furthermore, SFP112 modules maybe inserted into SFP-DD112 cage and connector using 1 of the electrical lanes.

{{ :networking:sfp14.jpg?600 |}}

**SFP-DD**

**SFP-DD probably is the Next Generation SFP Module to Support 100G**. By using this tiny SFP slot, it could realize the highest number of 100G front-panel pluggable ports in a Top-of-Rack switch. Eventually, two channels of 100G PAM4 will enable 200G per SFP-DD device. SFP28 are a speed enhanced variations of the predecessor SFP+ form factor, which was developed in 2014 under SFF Committee document SFF-8402 as well as earlier SFF-8472 and SFF-8432 specifications, define SFP28. SFP28 is targeted at enabling 25Gb/s to 28Gb/s applications, such as 25Gb/s Ethernet as well as 32GFC Fibre Channel. For the emerging generation of 50Gb/s to 56Gb/s PAM4 generation of SFPs, newer transceiver, connector and cage specifications might be required under a new name, called "SFP56". What's why SFP-DD also called "SFP56-DD".
SFP-DD electrical interfaces will employ 2 lanes that operate up to 25 Gbps NRZ modulation or 56 Gbps PAM4 modulation, providing solutions up to 50 Gbps or 112 Gbps PAM4 aggregate.

**SFP112**

**SFP112 probably is the world's smallest form factor of the 100G pluggable optics**, which is similar to the path of 10G with SFP+. It will be future proof, forward compatible, and target high manufacturability for high volume due to simplicity with less components, so ideally supports high-density applications of router switches and also provide an upgrade solution at 100G rate for the next generation wireless fronthaul networks.
The SFP112 will support 112 Gbps and the SFP-DD112 delivers an aggregate rate of 224 Gbps. This new revision also enables compatibility from SFP28/SFP56 to SFP112 and SFP-DD to SFP-DD112.

**SFP112 has been renamed to SFP2**

SFP-DD112 improved module paddle card 7.3 added option for double or triple split in the pre-wipe signal pads. SFP112 chapters are removed as they are now documented as SFP2 in the SFF-TA-1031.(SFP-DD MSA. October 27, 2023)

This is a specification for a 100Gbps transceiver package that is compatible with SFP+/SFP28, which was previously called SFP112. What is the origin of SFP112? Who decided on the name "SFP112"? The SFP-DD MSA Specifications are clearly defined. This is Nov 05,2011. After that, SFP112 appeared in Cisco's explanatory text and I think it gained recognition.

The case size is the same as SFP+/SFP28. Also applies to SFP56. For management, both SFF-8472 and CMIS can be applied, but CMIS is recommended for SFP56 and SFP112 (SFP2).
Regarding power consumption, it depends on the heat dissipation design, but it is expected to be up to 5.0W. There are also descriptions regarding more than that in the specifications. It is assumed that 48 ports can be arranged on the front panel of a 1U high device with a 19-inch rack width for heat dissipation.
As of July 2023, several SFP112 specification transceivers have been announced, but no Ethernet switches or NICs have been found that use them.

Demand for 40G and 100G transport links is growing quickly in recent years. Cloud computing, mobile broadband and IPTV are all driving user bandwidth. 40G links have been deployed for several years. Now, 40G transceivers are ubiquitous in modern data center. In recent two years, the optical industry buzz is all about “beyond 100G” bit rates. And the market for **100G data center optics** such as client-side 100G optical transceiver is accelerating. At present, there are several types of 100G optical transceivers launched to the market including **CXP, CFP, CFP2, CFP4, QSFP28**. Here will introduce and compare them in detail.

**100G CXP Transceiver**

**CXP is a kind of hot-pluggable 100G optical transceiver with data rate up to 12× 10 Gbps**. What does CXP mean? “C” represents for 12 in hex, and the Roman number “X” means that each channel has a transmission rate of 10 Gbps. “P” refers to pluggable that supports the hot swap. CXP is targeted at the clustering and high-speed computing markets and is the complement to CFP for Ethernet. Technically, the 100G CXP transceiver works with multimode fiber for short-reach applications, but it is not really optimized in size for the multimode fiber market, most notably because the multimode fiber market requires high faceplate density.


{{ :networking:sfp10.jpg?400 |}}

**CXP transceiver** is 45mm in length and 27mm in width, making it slightly larger than an XFP or 1/4 size of a CFP transceiver. It provides higher density network interfaces. It is a copper connector system specified by the InfiniBand Trade Association. It provides twelve 10 Gbps links suitable for 100 GbE, three 40 GbE Channels, or twelve 10 Gigabit Ethernet Channels or a single Infiniband 12× QDR link.

**100G CFP/CFP2/CFP4 Transceiver**

**The CFP Multi-Source Agreement (MSA)** defines hot-pluggable optical transceiver form factors to enable 40G and 100G applications, including next-generation High Speed Ethernet (40GbE and 100GbE). CFP transceiver supports both single-mode and multi-mode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces encompassed in the IEEE 802.3ba standard. There are three PMDs for 100 GbE: 100GBASE-SR10 for 100m, 100GBASE-LR4 for 10km, and 100GBASE-ER4 for 40km.

CFP was designed after the Small Form-factor Pluggable transceiver (SFP) interface, but is significantly larger to support 100Gbps. The electrical connection of a CFP uses 10x 10Gbps lanes in each direction (RX, TX). The optical connection can support both 10x 10Gbps and 4x 25Gbps variants. CFP transceivers can support a single 100Gbps signal like 100GE or OTU4 or one or more 40Gbps signals like 40GE, OTU3, or STM-256/OC-768.

Although CFP can achieve 100G application but its big size can no longer meet the demands of high-density data center. In this case, the CFP-MSA Committee has defined other two form factors: CFP2 and CFP4. The following picture shows the size comparison of 100G CFP, CFP2 and CFP4 modules:

{{ :networking:spf11.jpeg?600 |}}

{{ :networking:sfp8.png?600 |}}

CFP2 generally provides two solutions for 100G applications, as shown in the following picture:

{{ :networking:sfp15.jpg?400 |}}

**100G CFP4 is half the width of CFP2 transceiver**, which is half again the width of CFP. It’s more suitable for high-density applications. CFP4 solutions are shown as below:

{{ :networking:sfp16.jpg?400 |}}

**100G QSFP28 Transceiver**

Similarly, as a small size 100G optical transceiver for high-density applications, QSFP28 also attracts increasing attention. As its name suggests, QSFP28 have the same design concept, namely form factor as QSFP. The first-generation QSFP transceivers are equipped with four Tx and Rx and each channel has a rate of 10 Gbps. But for QSFP28 transceiver, each channel of QSFP can transmit and receive data up to 28Gbps. It is new for 100G applications. Compared with CFP4, QSFP28 is just slightly smaller than CFP4. QSFP28 seems to have the density advantage over CFP4, but CFP4’s higher maximum power consumption gives it the advantage on longer reach optical distances.

{{ :networking:sfp17.jpg?400 |}}

**100G CPAK Transceiver**

There is another 100G optical transceiver called CPAK in the market. CPAK transceiver is newcomer to this year’s demonstration. This is a proprietary form factor from Cisco but the interfaces demonstrated are IEEE standards and will interoperate with the same interfaces supported by other form-factors. Cisco believes that their CPAK is a good solution for 100G applications.

{{ :networking:sfp18.png?400 |}}

There is a richness of choice of 100G modules. In addition, 100G AOC (Active Optical Cable) assemblies are also launched to the market for short interconnection and 100G migration. Next year is going to be huge for 100 GbE. Meanwhile, with the rapid progress of technology, the 100G optics will become more cost-effective, 100G is no longer far away from us.
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**Conclusion: 200/400G Ethernet Approved**

Last December, the Ethernet committee approved a new standard, IEEE Std 802.3bs-2017: 200 Gb/s and 400 Gb/s Ethernet with seven variations.

  * **200GBASE-DR4**: 200 Gb/s transmission over four lanes (8 fibers total) of singlemode optical fiber cabling with reach up to at least 500 m
 
  * **200GBASE-FR4**: 200 Gb/s transmission over a 4 wavelength division multiplexed (WDM) lane (i.e. 2 fibers total) of singlemode optical fiber cabling with reach up to at least 2 km.

  * **200GBASE-LR4**: 200 Gb/s transmission over a 4 wavelength division multiplexed (WDM) lane (i.e. 2 fibers total) of singlemode optical fiber cabling with reach up to at least 10 km.

  * **400GBASE-SR16**: 400 Gb/s transmission over sixteen lanes (i.e. 32 fibers total) of multimode optical fiber cabling with reach up to at least 100 m.

  * **400GBASE-DR4**: 400 Gb/s transmission over four lanes (i.e. 8 fibers total) of singlemode optical fiber cabling with reach up to at least 500 m.

  * **400GBASE-FR8**: 400 Gb/s transmission over an 8 wavelength division multiplexed (WDM) lane (i.e. 2 fibers total) of singlemode optical fiber cabling with reach up to at least 2 km.

  * **400GBASE-LR8**: 400 Gb/s transmission over an 8 wavelength division multiplexed (WDM) lane (i.e. 2 fibers total) of singlemode optical fiber cabling with reach up to at least 10 km.

  * An **MPO-16** plug and receptacle is required to support the 32-fiber 400GBASE-SR16 multimode application. The MPO-16 plug is designed with an offset key to prevent accidental mating with a standard MPO/MTP receptacle. All 2-fiber applications may be supported with a 2‑fiber LC singlemode interface and all 8-fiber applications may be supported with standard MPO/MTP receptacles.

{{ :networking:sfp7.jpg?600 |}}

  Note: 100G SWDM4 is for VCSEL WDM on OM5 fiber.  100GBase-ZR is a tech marvel using special modulation and 
  coherent technology like long haul telecom. As you can see from the list above, the 400G standards are now 
  approved along with some 200G not listed here. Remember our quote (above) from Bob Metcalfe, co inventor of 
  Ethernet:  "The wonderful thing about standards is we have so many to choose from."

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**Addressing the New Paradigm**

**IEEE 802.3df™-2024**, **with its parallel x8 structure for 800 GbE**, enables Ethernet to address the reality of today’s networks where dual 400 GbE links are already being supported in a single x8 copper or optical connection. While this helped enable higher 400 GbE port density, it has emerged into even greater flexibility for configuring a port. Consider a given eight-lane port: it could be configured to support any of the following scenarios: a) one eight-lane implementation; b) two four-lane implementations; c) four two-lane implementations; d) eight one-lane implementations.

Thus, in combination with the standards noted in Table 1, a network architect can configure a single port to support standardized 100 GbE, 200 GbE, 400 GbE, or 800 GbE. This enables leveraging economies of scale to drive costs down throughout the entire ecosystem.


{{ :networking:sfp21.jpg?500 |}}

**Looking Ahead**

As previously highlighted from the latest IEEE 802.3™ Ethernet bandwidth assessment, by 2025 traffic levels are forecasted to be 2.3x to 55.4x the observed levels of 2017. While it is anticipated that IEEE 802.3df™-2024 will provide relief to a number of applications, the continuing exponential growth of industry bandwidth needs will necessitate the next rate of Ethernet sooner than the historical approximate 7 years that has been observed since 10 GbE.

The IEEE P802.3dj 200 Gb/s, 400 Gb/s, 800 Gb/s, and 1.6 Tb/s Ethernet Task Force emerged out of the IEEE P802.3df™ Task Force. The focus of this force will be on developing solutions based on 200 Gb/s or greater electrical and optical signaling. Those familiar with Ethernet are familiar with its propensity to provide upgrade paths. Therefore, the IEEE P802.3dj™ Task Force will be focused on solutions based on 1, 2, 4, and 8 lanes. As illustrated in Figure 3, with a lane rate of 200 Gb/s, solutions for 20 GbE, 400 GbE, 800 GbE, and the next Ethernet rate, 1.6 Tb/s, will be developed. This project is currently scheduled for completion in 2026.

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**FEC** on an SFP port refers to **Forward Error Correction (FEC)**, which is a technique used in fiber optic and Ethernet networks to enhance data transmission reliability by detecting and correcting errors without the need for retransmission.
 
**FEC (Forward Error Correction)**:
FEC is a mechanism that adds redundant information to the transmitted data. This redundancy allows the receiving end to detect and correct errors caused by signal degradation or noise during transmission.

Purpose: FEC is essential for high-speed data links (e.g., 10G, 25G, 40G, 100G Ethernet) to improve link quality and performance.

Types: Different FEC modes can be used depending on the standard and speed of the connection (e.g., Reed-Solomon FEC).


  *   **auto**   Enable FEC Auto-Neg
  *   **cl108**  Enable clause108 with 25G
  *   **cl74**   Enable clause74 with 25G
  *   **off**    Turn FEC off, FEC is mandatory for speeds 50G or higher


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**Benefits of FEC on SFP Ports**:

  * Error Correction: FEC can correct errors due to signal attenuation or interference.
  * Better Link Performance: Allows for longer cable runs or higher speeds by improving signal integrity.
  * No Retransmissions: Unlike other error correction methods, FEC works proactively without needing retransmissions, which is important for low-latency environments.

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**Aruba Switch 6400:**


  CS-2P-MDFHA-A#** show ver**
  -----------------------------------------------------------------------------
  ArubaOS-CX
  (c) Copyright 2017-2024 Hewlett Packard Enterprise Development LP
  -----------------------------------------------------------------------------
  Version      : FL.10.13.1010
  Build Date   : 2024-04-09 00:34:12 UTC
  Build ID     : ArubaOS-CX:FL.10.13.1010:ef2109377880:202404090010
  Build SHA    : ef21093778805e954ec130b0939d34927bb7ba19
  Hot Patches  :
  Active Image : primary
  
  Service OS Version : FL.01.14.0002
  BIOS Version       : FL.01.0002

CS-2P-MDFHA-A(config)# **interface 1/3/36**

**error-control**    Configure the error control (**FEC**) mode

  CS-2P-MDFHA-A(config-if)# error-control
    auto        Use the transceiver default
    base-r-fec  Use IEEE BASE-R (Firecode) FEC
    none        Do not use any FEC
    rs-fec      Use IEEE Reed-Solomon FEC

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**C9500 Cisco Catalyst**

C9500-N#**show ver**
  Cisco IOS XE Software, **Version 17.12.03**
  Cisco IOS Software [Dublin], Catalyst L3 Switch Software (CAT9K_IOSXE), Version 17.12.3, RELEASE SOFTWARE (fc7)

  interface TwentyFiveGigE1/0/3
   description VLAN 526 PTP A.B.C.D/EF X30
   switchport access vlan 526
   switchport mode access
   mtu 9100
   logging event trunk-status
   logging event bundle-status
   udld port aggressive
   fec cl74

  C9500-N(config-if)#interface TwentyFiveGigE1/0/3
  
  C9500-N(config-if)#fec ?
    auto   Enable FEC Auto-Neg
    cl108  Enable clause108 with 25G
    cl74   Enable clause74 with 25G
    off    Turn FEC off, FEC is mandatory for speeds 50G or higher

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