25 Gigabit Ethernet

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25 Gigabit Ethernet is a standard for Ethernet connectivity in a datacenter environment, developed by IEEE 802.3 task force P802.3by.[1]

50 Gigabit Ethernet is a proposed standard under development by the IEEE 802.3cd task force.[2]

History

An industry consortium (25G Ethernet Consortium [3]) 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,[4][5] and in November 2015, a study group was formed to explore the development of a single-lane 50-Gbit/s standard.[6]

In May 2016, an IEEE 802.3 task force was formed to develop a single-lane 50 GbE standard.[2]

On June 30, 2016, the IEEE 802.3by standard was approved by The IEEE-SA Standards Board.[7]

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).[8][9] The IEEE 802.3by standard defines:[10]

  • 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

25GBASE-T, a 25 Gbit/s standard over twisted pair, was approved alongside 40GBASE-T within IEEE 802.3bq.[11][12]

50 Gigabit Ethernet

The IEEE P802.3cd task force[2] 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-, 4- and 5-meter lengths are available from several manufacturers,[14] [15]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,[16] 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.The cable lengths are availabe in 0.5-, 1-, 2-, 3-, 4- and 5 meters. [17][18]

Server network adapters supported in Linux using a standard PCI-Express x8 interface are available.[19]

Intel

In January 2017, Intel launched the XXV-series 25 GbE network adapters.[20] These adapters are the first mainstream available 802.3by adapters and open 25 GbE for the big public. All three use SFP28-ports and support both CR Direct Attach Copper and SR & LR Optics. They communicate over a PCIe 3.0 x8 bus and come in multiple form factors.

Adapter XXV710-DA1OCP XXV710-DA1 XXV710-DA2
Ethernet 25 Gb/s
Ports 1 2
Interface PCIe 3.0 x8
Form factor OCP form factor (Mezz 2.0 Type 1) PCIe single slot low-profile
Connector SFP28
Cabling CR Direct Attach Copper

SR & LR Optics

Productinformation Intel Ark Intel Ark Intel Ark

Intel also launched six Direct Attach Copper cables, three SFP28 to SFP28 and three QSFP28 to SFP28, both in lengths of 1, 2 and 3 metres.[21] In addition, they launched a SFP28 SR optical tranciever.[22]

Cable Type Length
Intel XXVDACBL1M SFP28 Twinaxial Cable 1 m
Intel XXVDACBL2M 2 m
Intel XXVDACBL3M 3 m
Intel XXV4DACBL1M QSFP28 to SFP28 Twinaxial Breakout Cable 1 m
Intel XXV4DACBL2M 2 m
Intel XXV4DACBL3M 3 m
Intel E25GSFP28SR SFP28 Optical Module n/a

(max. 100 m)

References

  1. ^ IEEE 802.3by 25 Gb/s Ethernet Task Force
  2. ^ a b c IEEE 802.3cd 50 Gb/s, 100 Gb/s, and 200 Gb/s Ethernet Task Force
  3. ^ http://www.25gethernet.org/
  4. ^ Rick Merritt (2014-07-21). "25G Ethernet on Tap at IEEE". Retrieved 2014-09-29.
  5. ^ "IEEE 802.3 25 Gb/s Ethernet Study Group Public Area". IEEE 802.3. 2014-10-29. Retrieved 2014-12-31.
  6. ^ http://www.ieee802.org/3/50G/
  7. ^ "[STDS-802-3-25G] IEEE Std 802.3by-2016 Standard Approved!". 2016-06-30.
  8. ^ "Overview 25G & 50G Ethernet Specification, Draft 1.4" (PDF). 25G Ethernet Consortium. 2014-09-11. Retrieved 2014-12-31.
  9. ^ Stephen Hardy (July 23, 2014). "IEEE launches 25 Gigabit Ethernet Study Group". LightWave. Retrieved 2014-09-29.
  10. ^ http://www.ieee802.org/3/by/P802_3by_Objectives.pdf
  11. ^ "IEEE P802.3bq 25G/40GBASE-T Task Force". Retrieved 2016-02-08.
  12. ^ "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.
  13. ^ IEEE 802.3cd Task Force Objectives
  14. ^ "SFP28 direct attach".
  15. ^ "25G SFP28 Passive Direct Attach Copper Twinax Cable".
  16. ^ "SFP28 optical LR".
  17. ^ "100GbE QSFP28 to SFP28 breakout cable".
  18. ^ "100G QSFP28 to 4x25G SFP28 Breakout Cable".
  19. ^ "25GbE SFP28 based server adapter" (PDF).
  20. ^ "Intel® Ethernet Network Adapter XXV710". Intel. Retrieved 2017-04-18.
  21. ^ "Intel® Ethernet SFP28 Twinaxial Cables". Intel. Retrieved 2017-04-18.
  22. ^ "Intel® Ethernet SFP28 Optics". Intel. Retrieved 2017-04-18.

External links

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