25 Gigabit Ethernet

An industry consortium, 25G Ethernet Consortium,{{cite web |url=http://25gethernet.org/ |title=25G Ethernet Consortium |access-date=2017-09-17}} was formed by Arista, Broadcom, Google, Mellanox Technologies and Microsoft in July 2014 to support the specification of single-lane 25-Gbit/s Ethernet and dual-lane 50-Gbit/s Ethernet technology. The 25G Ethernet Consortium specification draft was completed in September 2015 and uses technology from IEEE Std. 802.3ba and IEEE Std. 802.3bj.

In November 2014, an IEEE 802.3 task force was formed to develop a single-lane 25-Gbit/s standard, and in November 2015, a study group was formed to explore the development of a single-lane 50-Gbit/s standard.{{cite web |url=http://www.ieee802.org/3/50G/ |title=Joint Webpage for IEEE 802.3 50 Gb/s Ethernet Over a Single Lane and Next Generation 100 Gb/s and 200 Gb/s Ethernet Study Group IEEE 802.3 200 Gb/s Ethernet Single-mode Fiber Study Group|website=Ieee802.org |access-date=2017-09-17}}

In May 2016, an IEEE 802.3 task force was formed to develop a single-lane 50 Gigabit Ethernet standard.

On June 30, 2016, the IEEE 802.3by standard was approved by The IEEE-SA Standards Board.{{Cite web|url=http://www.ieee802.org/3/25GSG/email/msg00556.html|title=[STDS-802-3-25G] IEEE Std 802.3by-2016 Standard Approved!|website=Ieee802.org|date=2016-06-30}}

On November 12, 2018, the IEEE P802.3cn Task Force started working to define PHY supporting 50-Gbit/s operation over at least 40 km of SMF.{{cite web|url=http://www.ieee802.org/3/cn/proj_doc/3cn_Objectives_181113.pdf|title=Adopted Objectives|website=Ieee802.org|access-date=19 November 2021}}

The IEEE 802.3cd standard was approved on December 5, 2018.

On December 20, 2019, the IEEE 802.3cn standard was published. {{Cite web|url=https://www.ieee802.org/3/email_dialog/msg01004.html|title=[802.3_DIALOG] March 2020 plenary meeting announcement|website=Ieee802.org|access-date=19 November 2021}}

On April 6, 2020, 25 Gigabit Ethernet Consortium has rebranded to Ethernet Technology Consortium, and it announces 800 Gigabit Ethernet (GbE) specification.{{Cite web|url=https://ethernettechnologyconsortium.org/press-room/press-releases/25-gigabit-ethernet-consortium-rebrands-to-ethernet-technology-consortium-announces-800-gigabit-ethernet-gbe-specification-152/|title=25 Gigabit Ethernet Consortium Rebrands to Ethernet Technology Consortium; Announces 800 Gigabit Ethernet (GbE) Specification|website=Ethernettechnologyconsortium.org|date=2020-04-06}}

On June 4, 2020, the IEEE approved IEEE 802.3ca which allows for symmetric or asymmetric operation with downstream speeds of 25 or {{nowrap|50 Gbit/s}}, and upstream speeds of 10, 25, or {{nowrap|50 Gbit/s}} over passive optical networks.{{cite web | title = IEEE 802.3ca-2020 - IEEE Standard for Ethernet Amendment 9 | url = https://standards.ieee.org/ieee/802.3ca/7440/ | publisher = IEEE | date = 2020-07-03 }}{{cite web | url = https://www.cablelabs.com/25g-50g-epon-standard-crosses-the-finish-line-enhancing-fiber-deployments-as-part-of-cables-10g-platform | title = 25G/50G-EPON Standard Crosses the Finish Line – Enhancing Fiber Deployments as Part of Cable's 10G Platform | first = Curtis | last = Knittle | publisher = CableLabs | date = 2020-07-23 }}

The IEEE 802.3by standard uses technology defined for 100 Gigabit Ethernet implemented as four 25-Gbit/s lanes (IEEE 802.3bj). The IEEE 802.3by standard defines several single-lane variations.{{cite web |url=http://www.ieee802.org/3/by/P802_3by_Objectives.pdf |title=Adopted & Approved Objectives: 25 Gb/s Ethernet over a single lane for server interconnect|website=Ieee802.org |access-date=2017-09-17}}

{{Fibre legend}}

; {{Visible anchor|25GBASE-T}}

: 25GBASE-T, a 25-Gbit/s standard over twisted pair, was approved alongside 40GBASE-T within IEEE 802.3bq.{{Cite web|url=http://www.ieee802.org/3/bq/index.html |title=IEEE P802.3bq 25G/40GBASE-T Task Force |website=Ieee802.org|access-date=2016-02-08}}{{Cite web|url=http://www.ieee802.org/3/NGBASET/email/msg00972.html | publisher = IEEE | title = Approval of IEEE Std 802.3by-2016, IEEE Std 802.3bq-2016, IEEE Std 802.3bp-2016 and IEEE Std 802.3br-2016 |website=Ieee802.org|date=2016-06-30}}

All fibre and twisted pair versions of 25 Gigabit Ethernet are required to support Reed-Solomon Forward Error Correction, often abbreviated RS-FEC, defined in clause 108 of the IEEE 802.3 standard. This also applies to 25GBASE-CR but not to 25GBASE-CR-S, both of which are variants used in DAC cables. 25GBASE-CR as well as 25GBASE-CR-S are required to support Fire-Code FEC (BASE-R FEC, also FC-FEC, defined in clause 74 of IEEE 802.3).IEEE 802.3 clauses 110, 112, 113 and 114 While RS-FEC has to be supported for the mentioned 25 G versions, clause 108 also mandates that it has to be possible to turn FEC off, which makes it possible to not use FEC if desired.

For an Ethernet link to form, the interfaces involved must use the same type of FEC or no FEC.https://cdrdv2-public.intel.com/630739/630739_25%20Gb%20Intel%C2%AE%20Ethernet%20Media%20Guide%20Application%20Note.pdf

The IEEE {{not a typo|P802.3cd}} standard defines a Physical Coding Sublayer (PCS) in Clause 133 which after encoding gives a data rate of {{nowrap|51.5625 Gbit/s}}. 802.3cd also defines an RS-FEC for forward error correction in Clause 134 which after FEC encoding gives a data rate of {{nowrap|53.125 Gbit/s}}. It is not possible to transmit {{nowrap|53.125 Gbit/s}} over an electrical interface while maintaining suitable signal integrity so four-level pulse-amplitude modulation (PAM4) is used to map pairs of bits into a single symbol. This leads to an overall baud rate of 26.5625 GBd for {{nowrap|50 Gbit/s}} per lane Ethernet. PAM4 encoding for 50G Ethernet is defined in Clause 135 of the 802.3 standard.

{{Fibre legend}}

{{As of|June 2016}}, 25 Gigabit Ethernet equipment is available on the market using the SFP28 and QSFP28 transceiver form factors. Direct attach SFP28-to-SFP28 copper cables in 1-, 2-, 3- and 5-meter lengths are available from several manufacturers, and optical transceiver manufacturers have announced 1310 nm "LR" optics intended for reach distances of 2 to 10 km over two strands of standard single-mode fiber, similar to existing 10GBASE-LR optics, as well as 850 nm "SR" optics intended for short reach distances of 100 m over two strands of OM4 multimode fiber, similar to existing 10GBASE-SR optics.{{cn|date=November 2018}}

• Ethernet Alliance

{{Reflist|30em|refs=

{{cite web |title=IEEE 802.3 25 Gb/s Ethernet Study Group Public Area |url=http://www.ieee802.org/3/25GSG/public/index.html |date=2014-10-29 |publisher=IEEE 802.3 |access-date=2014-12-31}}

{{cite web |title=Overview 25G & 50G Ethernet Specification, Draft 1.4 |url=http://25gethernet.org/sites/default/files/25G%20and%2050G%20Specification%20Overview.pdf |date=2014-09-11 |publisher=25G Ethernet Consortium |access-date=2014-12-31}}

{{cite web |title=IEEE launches 25 Gigabit Ethernet Study Group |url=http://www.lightwaveonline.com/articles/2014/07/ieee-launches-25-gigabit-ethernet-study-group.html |author=Stephen Hardy |date=July 23, 2014 |publisher=LightWave |access-date=2014-09-29}}

{{cite news |title=25G Ethernet on Tap at IEEE |url=http://www.eetimes.com/document.asp?doc_id=1323184 |author=Rick Merritt |date=2014-07-21 |access-date=2014-09-29}}

}}

• [https://ethernettechnologyconsortium.org Ethernet Technology Consortium]
• [https://ultraethernet.org Ultra Ethernet Consortium]
• {{cite web |title=What is 25 Gigabit Ethernet and why would you want it? |url=http://www.plexxi.com/2014/07/whats-25-gigabit-ethernet-want/#sthash.pmA8yPck.dpbs |access-date=2014-09-29}}

{{Ethernet}}

Category:Ethernet