40 Gigabit Ethernet (40GbE) and 100 Gigabit Ethernet (100GbE) are groups of computer networking technologies for transmitting Ethernet frames at rates of 40 and 100 gigabits per second (Gbit/s), respectively. These technologies offer significantly higher speeds than 10 Gigabit Ethernet. The technology was first defined by the IEEE 802.3ba-2010 standard and later by the 802.3bg-2011, 802.3bj-2014, 802.3bm-2015, and 802.3cd-2018 standards. The first succeeding Terabit Ethernet specifications were approved in 2017.such as IEEE 802.3bs-2017
The standards define numerous port types with different optical and electrical interfaces and different numbers of optical fiber strands per port. Short distances (e.g. 7 m) over twinaxial cable are supported, while standards for fiber reach up to 80 km.
Standards The IEEE 802.3 working group is concerned with the maintenance and extension of the Ethernet data communications standard. Additions to the 802.3 standard are performed by task forces which are designated by one or two letters. For example, the 802.3z task force drafted the original Gigabit Ethernet standard.
802.3ba is the designation given to the higher-speed Ethernet task force, which completed its work to modify the 802.3 standard to support speeds higher than in 2010.
The speeds chosen by 802.3ba were 40 and to support both end-point and link aggregation needs, respectively. This was the first time two different Ethernet speeds were specified in a single standard. The decision to include both speeds came from pressure to support the rate for local server applications and the rate for internet backbones. The standard was announced in July 2007 and was ratified on June 17, 2010.
The 40/100 Gigabit Ethernet standards encompass a number of different Ethernet physical layer (PHY) specifications. A networking device may support different PHY types by means of pluggable modules. Optical modules are not standardized by any official standards body but are in multi-source agreements (MSAs). One agreement that supports 40 and 100 Gigabit Ethernet is the CFP MSA which was adopted for distances of 100+ meters. QSFP and CXP connector modules support shorter distances.
The standard supports only full-duplex operation. Other objectives include:
Preserve the 802.3 Ethernet frame format utilizing the 802.3 MAC Preserve minimum and maximum frame size specified in the 802.3 standard Support a bit error rate (BER) better than or equal to 10−12 at the MAC/PLS service interface Provide appropriate support for OTN Support MAC data rates of 40 and Provide physical layer specifications (PHY) for operation over single-mode optical fiber (SMF), laser optimized multi-mode optical fiber (MMF) OM3 and OM4, copper cable assembly, and backplane.
The following nomenclature is used for the physical layers:
Physical layer40 Gigabit Ethernet100 Gigabit EthernetBackplane100GBASE-KP4Improved Backplane40GBASE-KR4100GBASE-KR4100GBASE-KR27 m over twinax copper cable40GBASE-CR4100GBASE-CR10100GBASE-CR4100GBASE-CR230 m over Category 8 twisted pair40GBASE-T100 m over OM3 MMF40GBASE-SR4100GBASE-SR10100GBASE-SR4100GBASE-SR2125 m over OM4 MMF500 m over SMF, serial100GBASE-DR2 km over SMF, serial40GBASE-FR100GBASE-FR110 km over SMF40GBASE-LR4100GBASE-LR4100GBASE-LR140 km over SMF80 km over SMF100GBASE-ZR
The 100 m laser-optimized multi-mode fiber (OM3) objective is met by parallel ribbon cable with 850 nm wavelength 10GBASE-SR-like optics (40GBASE-SR4 and 100GBASE-SR10). The backplane objective is met with 4 lanes of 10GBASE-KR type PHYs (40GBASE-KR4). The copper cable objective is met with 4 or 10 differential lanes using SFF-8642 and SFF-8436 connectors. The 10 and 40 km objectives with four wavelengths (around 1310 nm) of optics (100GBASE-LR4 and 100GBASE-ER4) and the 10 km objective with four wavelengths (around 1310 nm) of optics (40GBASE-LR4).
In January 2010, another IEEE project authorization started a task force to define a serial single-mode optical fiber standard (40GBASE-FR). This was approved as standard 802.3bg in March 2011. It used 1550 nm optics, had a reach of 2 km and was capable of receiving 1550 nm and 1310 nm wavelengths of light. The capability to receive 1310 nm light allows it to interoperate with a longer-reach 1310 nm PHY should one ever be developed. 1550 nm was chosen as the wavelength for 802.3bg transmission to make it compatible with existing test equipment and infrastructure.
In December 2010, a 10x10 multi-source agreement (10x10 MSA) began to define an optical Physical Medium Dependent (PMD) sublayer and establish compatible sources of low-cost, low-power, pluggable optical transceivers based on 10 optical lanes at each. The 10x10 MSA was intended as a lower cost alternative to 100GBASE-LR4 for applications which do not require a link length longer than 2 km. It was intended for use with standard single-mode G.652.C/D type low water peak cable with ten wavelengths ranging from 1523 to 1595 nm. The founding members were Google, Brocade Communications, JDSU and Santur. Other member companies of the 10x10 MSA included MRV, Enablence, Cyoptics, AFOP, oplink, Hitachi Cable America, AMS-IX, EXFO, Huawei, Kotura, Facebook and Effdon when the 2 km specification was announced in March 2011. The 10X10 MSA modules were intended to be the same size as the CFP specifications.
On June 12, 2014, the 802.3bj standard was approved. The 802.3bj standard specifies 4x25G PHYs - 100GBASE-KR4, 100GBASE-KP4 and 100GBASE-CR4 - for backplane and twin-ax cable.
On February 16, 2015, the 802.3bm standard was approved. The 802.3bm standard specifies a lower-cost optical 100GBASE-SR4 PHY for MMF and a four-lane chip-to-module and chip-to-chip electrical specification (CAUI-4). The detailed objectives for the 802.3bm project can be found on the 802.3 website.
On May 14, 2018, the 802.3ck project was approved. This has objectives to: Define a single-lane Attachment Unit interface (AUI) for chip-to-module applications, compatible with PMDs based on per lane optical signaling (100GAUI-1 C2M) Define a single-lane Attachment Unit Interface (AUI) for chip-to-chip applications (100GAUI-1 C2C) Define a single-lane PHY for operation over electrical backplanes supporting an insertion loss ≤ 28 dB at 26.56 GHz (100GBASE-KR1). Define a single-lane PHY for operation over twin-axial copper cables with lengths up to at least 2 m (100GBASE-CR1).
On November 12, 2018, the IEEE P802.3ct Task Force started working to define PHY supporting operation on a single wavelength capable of at least 80 km over a DWDM system (100GBASE-ZR) (using a combination of phase and amplitude modulation with coherent detection).
On December 5, 2018, the 802.3cd standard was approved. The 802.3cd standard specifies PHYs using lanes - 100GBASE-KR2 for backplane, 100GBASE-CR2 for twin-ax cable, 100GBASE-SR2 for MMF and using signalling 100GBASE-DR for SMF.
In June 2020, the IEEE P802.3db Task Force started working to define a physical layer specification that supports operation over 1 pair of MMF with lengths up to at least 50 m.
On February 11, 2021, the IEEE 802.3cu standard was approved. The IEEE 802.3cu standard defines single-wavelength PHYs for operation over SMF (Single-Mode Fiber) with lengths of at least 2 km (100GBASE-FR1) and 10 km (100GBASE-LR1).
40G/100G pluggable module types
The electrical and physical interface on devices implementing 100 Gigabit Ethernet has undergone a process of miniaturization, as has been seen on older generations of Ethernet.
Name Introduction 40GE 100GE Electrical interfacesrowspan="2" rowspan="2" Notes Single-issue form factors CXP historical, limited standardization CPAK historical, limited standardization CFP 2009 MDIO Generally phased out, but still seen for very high power or coherent optical transceivers. CFP2 2013 Specification includes 400G usage (8 × 25.78125 Gbaud × PAM4). Generally phased out, but still seen for very high power or coherent optical transceivers. CFP4 2014 Generally phased out. microQSFP 2016 I²C DSFP 2018 Multi-generation form factors QSFP family no suffix I²C rowspan="2" QSFP28 is the most common form factor as of 2026. Slower/older transceivers can frequently (but not always) be used in faster ports. -DD colspan="2" SFP family no suffix rowspan="2" Hosts are commonly backwards compatible with SFP/SFP28 modules for 10GE and 25GE operation. -DD OSFP family
Multipliers in this table indicate the given module would be able to provide the given number of 100GE interfaces. This usage is common with breakout cabling, but must be supported by the platform. The higher the breakout ratio is, the less commonly it is supported, and these ports would normally be used for 400GE or 800GE.
The electrical interface listed above doesn't necessarily tie into a symbol rate or encoding on optical media. A module may implement a gearbox to covert between encodings, sometimes even regenerating or converting between forward error correction schemes. For SFP and QSFP form factors, this was initially too power hungry but is now not uncommon.
Optical transceivers supporting multiple symbol rates exist but are, while not rare, somewhat uncommon. On the host side, multi-rate ports are relatively common, meaning module slots can accept older/slower modules within the same physical form factor. However, support differs across platforms, and some can only switch rates for a group of several ports at once, i.e., all ports within the group must use the same symbol rate.
100G interface types
In theory, any optical interface standard could be implemented in any form factor module, although the front surface of SFP modules is too small to fit an MPO connector. However, not all combinations have been manufactured. The list of available optical standards is: