25 Gigabit Ethernet
25 Gigabit Ethernet is a standard for Ethernet connectivity in a datacenter environment, developed by IEEE 802.3 task force P802.3by.[1] 25GBASE-T, a 25 Gbit/s standard over twisted pair, was approved alongside 40GBASE-T within IEEE 802.3bq.[2][3]
50 Gigabit Ethernet is a proposed standard under development by the IEEE 802.3cd task force.[4]
History
An industry consortium (25G Ethernet Consortium [5]) was formed 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.bj.
In November 2014, an IEEE 802.3 task force was formed to develop a single-lane 25-Gbit/s standard,[6][7] and in November 2015, a study group was formed to explore the development of a single-lane 50-Gbit/s standard.[8]
In May 2016, an IEEE 802.3 task force was formed to develop a single-lane 50 GbE standard.[4]
On June 30, 2016, the IEEE 802.3by standard was approved by The IEEE-SA Standards Board.[9]
25 Gigabit Ethernet
The IEEE 802.3by standard uses technology defined for 100 Gigabit Ethernet implemented as four 25-Gbit/s lanes (IEEE 802.3bj).[10][11] The IEEE 802.3by standard defines:[12]
- a single-lane 25 Gbit/s 25GBASE-KR PHY for printed circuit backplanes
- a single-lane 25 Gbit/s 25GBASE-CR-S PHY for 3 m twin-ax cables (in-rack)
- a single-lane 25 Gbit/s 25GBASE-CR-L PHY for 5 m twin-ax cables (inter-rack)
- a single-lane 25 Gbit/s 25GBASE-SR PHY for 100 m OM4 or 70 m OM3 multi-mode optical fiber
50 Gigabit Ethernet
The IEEE P802.3cd task force[4] is working with the objectives to define single-lane 50 Gbit/s PHYs for operation over:[13]
- copper twin-axial cables with lengths up to at least 3m
- printed circuit board backplane
- MMF with lengths up to at least 100m
- SMF with lengths up to at least 2 km
- SMF with lengths up to at least 10 km
Availability
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,[14] and optical transceiver manufacturers have announced 1310 nm "LR" optics intended for reach distances of 2 to 10 km over two strands of standard singlemode fiber,[15] similar to existing 10GBASE-LR optics.
Breakout type direct attach cables also exist which adapt a single QSFP28 format 100GbE port to four independent 25 Gbit/sec SFP28 connections.[16]
Server network adapters supported in Linux using a standard PCI-Express x8 interface are available.[17]
References
- ↑ IEEE 802.3by 25 Gb/s Ethernet Task Force
- ↑ "IEEE P802.3bq 25G/40GBASE-T Task Force". Retrieved 2016-02-08.
- ↑ "Approval of IEEE Std 802.3by-2016, IEEE Std 802.3bq-2016, IEEE Std 802.3bp-2016 and IEEE Std 802.3br-2016". IEEE. 2016-06-30.
- 1 2 3 IEEE 802.3cd 50 Gb/s, 100 Gb/s, and 200 Gb/s Ethernet Task Force
- ↑ http://www.25gethernet.org/
- ↑ Rick Merritt (2014-07-21). "25G Ethernet on Tap at IEEE". Retrieved 2014-09-29.
- ↑ "IEEE 802.3 25 Gb/s Ethernet Study Group Public Area". IEEE 802.3. 2014-10-29. Retrieved 2014-12-31.
- ↑ http://www.ieee802.org/3/50G/
- ↑ "[STDS-802-3-25G] IEEE Std 802.3by-2016 Standard Approved!". 2016-06-30.
- ↑ "Overview 25G & 50G Ethernet Specification, Draft 1.4" (PDF). 25G Ethernet Consortium. 2014-09-11. Retrieved 2014-12-31.
- ↑ Stephen Hardy (July 23, 2014). "IEEE launches 25 Gigabit Ethernet Study Group". LightWave. Retrieved 2014-09-29.
- ↑ http://www.ieee802.org/3/by/P802_3by_Objectives.pdf
- ↑ IEEE 802.3cd Task Force Objectives
- ↑ "SFP28 direct attach".
- ↑ "SFP28 optical LR".
- ↑ "100GbE QSFP28 to SFP28 breakout cable".
- ↑ "25GbE SFP28 based server adapter" (PDF).
External links
- 25G Ethernet Consortium
- "What is 25 Gigabit Ethernet and why would you want it?". Retrieved 2014-09-29.