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] and is available from multiple vendors.
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 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,[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 several single-lane variations.[10]
25GBASE-T, a 25 Gbit/s standard over twisted pair, was approved alongside 40GBASE-T within IEEE 802.3bq.[11][12]
| MMF FDDI 62,5/125 µm (1987) |
MMF OM1 62,5/125 µm (1989) |
MMF OM2 50/125 µm (1998) |
MMF OM3 50/125 µm (2003) |
MMF OM4 50/125 µm (2008) |
MMF OM5 50/125 µm (2016) |
SMF OS1 9/125 µm (1998) |
SMF OS2 9/125 µm (2000) |
|---|---|---|---|---|---|---|---|
| 160 MHz·km @850 nm |
200 MHz·km @850 nm |
500 MHz·km @850 nm |
1500 MHz·km @850 nm |
3500 MHz·km @850 nm |
3500 MHz·km @850 nm & 1850 MHz·km @950 nm |
1 dB/km @1300/ 1550 nm |
0.4 dB/km @1300/ 1550 nm |
| Name | Standard | Status | Media | OFC or RFC | Transceiver Module |
Reach in km |
# Media |
Lanes (⇅) |
Notes |
|---|---|---|---|---|---|---|---|---|---|
| 25 Gigabit Ethernet (25 GbE) - (Data rate: 25 Gbit/s - Line code: 64b/66b with RS-FEC × NRZ - Line rate: 25.7813 GBd - Full-Duplex) [14] | |||||||||
| 25GBASE -CR Direct Attach |
802.3by-2016 (CL110) |
current | twinaxial balanced |
SFP28 (SFF-8402) |
SFP28 | 0.005 | 2 | 1 | Data centres (inter-rack) |
| 25GBASE -CR-S Direct Attach |
802.3by-2016 (CL110) |
current | twinaxial balanced |
SFP28 (SFF-8402) |
SFP28 | 0.003 | 1 | 1 | Data centres (in-rack); without RS-FEC (802.3by CL108) |
| 25GBASE -KR |
802.3by-2016 (CL111) |
current | Cu-Backplane | N/A | N/A | 0.001 | 1 | 2 | PCBs |
| 25GBASE -KR-S |
802.3by-2016 (CL111) |
current | Cu-Backplane | N/A | N/A | 0.001 | 1 | 1 | PCBs; without RS-FEC (802.3by CL108) |
| 25GAUI | 802.3by-2016 (CL109A/B) |
current | Cu-Backplane | N/A | N/A | 0.00025 | 2 | 1 | PCBs: Chip-to-chip / chip-to-module interface |
| 25GBASE -SR |
802.3by-2016 (CL112) |
current | Fibre 850 nm |
LC | SFP28 | OM3: 0.07 | 2 | 1 | |
| OM4: 0.1 | |||||||||
| 25GBASE -LR |
802.3cc-2017 (CL114) |
current | Fibre 1295 – 1325 nm |
LC | SFP28 | OSx: 10 | 2 | 1 | |
| 25GBASE -ER |
802.3cc-2017 (CL114) |
current | Fibre 1550 nm |
LC | SFP28 | OSx: 40 | 2 | 1 | |
| Name | Clause (standard) | Medium | Media Count | Gigabaud per lane | Reach | RS-FEC (802.3by clause 108) |
|---|---|---|---|---|---|---|
| 25GBASE-T | 113 (802.3bq) | Cat 8 balanced twisted-pair structured cabling | 4 pairs | 2.000 | 30 m | No |
50 Gigabit Ethernet
The IEEE P802.3cd [2] standard defines a Physical Coding Sublayer (PCS) in Clause 133 which after encoding gives a data-rate of 51.5625 Gbps. 802.3cd also defines an RS-FEC for forward error correction in Clause 134 which after FEC encoding gives a data-rate of 53.125 Gbps. It is not possible to transmit 53.125 Gbps 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 50 Gbps per lane Ethernet. PAM4 encoding for 50G Ethernet is defined in Clause 135 of the 802.3 standard.
| MMF FDDI 62,5/125 µm (1987) |
MMF OM1 62,5/125 µm (1989) |
MMF OM2 50/125 µm (1998) |
MMF OM3 50/125 µm (2003) |
MMF OM4 50/125 µm (2008) |
MMF OM5 50/125 µm (2016) |
SMF OS1 9/125 µm (1998) |
SMF OS2 9/125 µm (2000) |
|---|---|---|---|---|---|---|---|
| 160 MHz·km @850 nm |
200 MHz·km @850 nm |
500 MHz·km @850 nm |
1500 MHz·km @850 nm |
3500 MHz·km @850 nm |
3500 MHz·km @850 nm & 1850 MHz·km @950 nm |
1 dB/km @1300/ 1550 nm |
0.4 dB/km @1300/ 1550 nm |
| Name | Standard | Status | Media | OFC or RFC | Transceiver Module |
Reach in km |
# Media |
Lanes (⇅) |
Notes |
|---|---|---|---|---|---|---|---|---|---|
| 50 Gigabit Ethernet (50 GbE) - (Data rate: 50 Gbit/s - Line code: 256b/257b × RS-FEC(544,514) × PAM4 - Line rate: 26.5625 GBd - Full-Duplex) - Full-Duplex) [15][16] | |||||||||
| 50GBASE -CR |
802.3cd-2018 (CL133/136) |
develop- ment |
twinaxial balanced |
QSFP+ (SFF-8635) |
QSFP+ | 0.003 | 1 | 1 | Data centres (in-rack) |
| 50GBASE -KR |
802.3cd-2018 (CL133/137) |
develop- ment |
Cu-Backplane | N/A | N/A | 0.001 | 1 | 1 | PCBs; total channel insertion loss ≤ 30 dB at half sampling rate = 13.28125 GHz (Nyquist). |
| 50GBASE -SR |
802.3cd-2018 (CL133/138) |
develop- ment |
Fibre 850 nm |
LC | QSFP+ | OM3: 0.07 | 2 | 1 | |
| OM4: 0.1 | |||||||||
| 50GBASE -LR |
802.3cd-2018 (CL133/139) |
develop- ment |
Fibre 1304.5 – 1317.5 nm |
LC | QSFP+ | OSx: 10 | 2 | 1 | |
| 50GBASE -FR |
802.3cd-2018 (CL133/139) |
develop- ment |
Fibre 1304.5 – 1317.5 nm |
LC | QSFP+ | OSx: 2 | 2 | 1 | |
| LAUI-2 | 802.3cd-2018 (CL135B/C) |
develop- ment |
Cu-Backplane | N/A | N/A | 0.00025 | 2 | 2 | PCBs: Chip-to-chip/chip-to-module interface; Line code: NRZ (no FEC) Line rate: 2x 26.5625 GBd = 53.1250 GBd |
| 50GAUI-2 | 802.3cd-2018 (CL135D/E) |
develop- ment |
Cu-Backplane | N/A | N/A | 0.00025 | 2 | 2 | PCBs: Chip-to-chip/chip-to-module interface; Line code: NRZ (FEC encoded) Line rate: 2x 25.78125 GBd = 51.5625 GBd |
| 50GAUI-1 | 802.3cd-2018 (CL135F/G) |
develop- ment |
Cu-Backplane | N/A | N/A | 0.00025 | 1 | 1 | PCBs: Chip-to-chip/chip-to-module interface |
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,[17] 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,[18] similar to existing 10GBASE-LR optics, as well as 850 nm "SR" optics [19] intended for short reach distances of 100 m over two strands of OM4 multimode fiber,similar to existing 10GBASE-SR optics.
Breakout type direct attach cables also exist which adapt a single QSFP28 format 100GbE port to four independent 25 Gbit/sec SFP28 connections.,[20] the cable length is available in 1-meter to 5-meter.[21]
Server network adapters supported in Linux using a standard PCI-Express x8 interface are available.[22]
Netronome
In August 2016, Netronome launched the Agilio CX 25GbE smart network adapter (SmartNIC)[23]. In March 2018, Netronome launched the Agilio CX 25GbE SmartNIC in OCP v2.0 form factor[24]. The Agilio SmartNIC platform fully and transparently offloads eBPF, virtual switch, virtual router, and P4-based datapath processing for networking functions such as overlays, security, load balancing and telemetry.
| Adapter | Agilio CX | Agilio CX for OCP v2.0 |
|---|---|---|
| Ethernet | 25 Gbit/s | 25Gbit/s |
| Ports | 2 | 1 |
| Interface | PCie Gen3 | PCIe 3.0 x8 |
| Form factor | PCIe single slot, low-profile | OCP form factor (Mezz 2.0) |
| Connector | SFP28 | SFP28 |
| Cabling | CR Direct Attach Copper
SR & LR Optics |
CR Direct Attach Copper
SR & LR Optics |
| Product Information | Agilio CX 25GbE SmartNIC | Agilio CX 25GbE SmartNIC for OCP |
Mellanox Technologies
Mellanox was the first company to introduce 25 GbE network adapters to the market and has the biggest market share according to Crehan Research analyst firm with more than 70% for 2016. The Mellanox adapters provide Intelligent RDMA capabilities, and advanced application offloads such as RoCE, OVS, DPDK, NFV and more.
The below table covers the basic information of the latest adapters:
| Adapter | ConnectX-4 Lx | ConnectX-5 |
|---|---|---|
| Ethernet | 25 Gbit/s | 25Gbit/s |
| Ports | 1,2 | 1,2 |
| Interface | PCie Gen3 | PCIe Gen3, PCIe Gen4 |
| Form Factor | PCIe, OCP and OEM specific | PCIe, OCP and OEM specific |
| Connector | SFP28 | SFP28 |
| Cabling | Copper and Fiber | Copper and Fiber |
| Part Number | MCX4111A-A, MCX4121A-A | MCX512A-ACAT |
| Product Information | http://www.mellanox.com/page/ethernet_cards_overview | |
Intel
In January 2017, Intel launched the XXV-series 25 GbE network adapters.[25] These adapters are 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 Gbit/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.[26] In addition, they launched a SFP28 SR optical transceiver.[27]
| 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
- ↑ IEEE 802.3by 25 Gb/s Ethernet Task Force
- 1 2 3 IEEE 802.3cd 50 Gb/s, 100 Gb/s, and 200 Gb/s Ethernet Task Force
- ↑ "25G Ethernet Consortium". Retrieved 2017-09-17.
- ↑ 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.
- ↑ "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". Retrieved 2017-09-17.
- ↑ "[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.
- ↑ "Adopted & Approved Objectives: 25 Gb/s Ethernet over a single lane for server interconnect" (PDF). Retrieved 2017-09-17.
- ↑ "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 Charles E. Spurgeon (2014). Ethernet: The Definitive Guide (2nd ed.). O'Reilly Media. ISBN 978-1-4493-6184-6.
- ↑ "Evolution of Ethernet Speeds: What's New and What's Next" (PDF). Alcatel-Lucent. 2015-06-03. Retrieved 2018-08-28.
- ↑ "Exploring The IEEE 802 Ethernet Ecosystem" (PDF). IEEE. 2017-06-04. Retrieved 2018-08-29.
- ↑ "Multi-Port Implementations of 50/100/200GbE" (PDF). Brocade. 2016-05-22. Retrieved 2018-08-29.
- ↑ "SFP28 direct attach".
- ↑ "SFP28 optical LR".
- ↑ "25G SFP28 SR Transceiver".
- ↑ "100GbE QSFP28 to SFP28 breakout cable".
- ↑ "100G QSFP28 to 4x25G SFP28 Passive Direct Attach Copper Breakout Cable".
- ↑ "25GbE SFP28 based server adapter" (PDF).
- ↑ https://www.netronome.com/press-releases/netronome-announces-25gbe-smartnics-with-openstack-firewall-security-and-open-vswitch-acceleration/
- ↑ https://www.netronome.com/press-releases/netronome-introduces-worlds-smallest-lowest-power-2550gbe-smartnics-based-ocp-v20-mezzanine-specification/
- ↑ "Intel® Ethernet Network Adapter XXV710". Intel. Retrieved 2017-04-18.
- ↑ "Intel® Ethernet SFP28 Twinaxial Cables". Intel. Retrieved 2017-04-18.
- ↑ "Intel® Ethernet SFP28 Optics". Intel. Retrieved 2017-04-18.
External links
- 25G Ethernet Consortium
- "What is 25 Gigabit Ethernet and why would you want it?". Retrieved 2014-09-29.