2.5GBASE-T and 5GBASE-T
IEEE 802.3bz, NBASE-T and MGBASE-T are standards for Ethernet over twisted pair at speeds of 2.5 and 5 Gbit/s. These use the same cabling as the ubiquitous Gigabit Ethernet, yet offer higher speeds. The resulting standards are named 2.5GBASE-T and 5GBASE-T.[1][2][3]
NBASE-T refers to Ethernet equipment that can automatically negotiate to operate at speeds of 100 Mbit/s, 1, 2.5, 5, or 10 Gbit/s, depending on the quality of the cable and the capabilities of the equipment at the other end of the cable.[citation needed]
Technology[edit]
These standards are specified in Clauses 125 and 126 of the IEEE 802.3 standard. The physical (PHY) layer transmission technology of IEEE 802.3bz is based on 10GBASE-T, but operates at a lower signaling rate. By reducing the original signal rate to 1⁄4 or 1⁄2, the link speed drops to 2.5 or 5 Gbit/s, respectively.[4] The spectral bandwidth of the signal is reduced accordingly, lowering the requirements on the cabling, so that 2.5GBASE-T and 5GBASE-T can be deployed at a cable length of up to 100 m on Cat 5e or better cables.[5][6] The 2.5GBASE-T1 and 5GBASE-T1 variants that can run over a single pair of balance conductors up to 15 m in length is standardized in 802.3ch-2020;[7] their primary use case field is in embedded automotive applications.
The NBASE-T effort also standardized how its switches can implement power over Ethernet according to the IEEE 802.3at and successor standards. This allows a single cable to provide both power and data for high-bandwidth wireless access points such as those that implement the 802.11ac and 802.11ax standards.[8]
Name | Standard | Status | Speed (Mbit/s) | Pairs required | Lanes per direction | Bits per hertz | Line code | Symbol rate per lane (MBd) | Bandwidth | Max distance (m) | Cable | Cable rating (MHz) | Usage |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2.5GBASE-T | 802.3bz-2016 | current | 2500 | 4 | 4 | 6.25 | 64B65B PAM-16 128-DSQ | 200 | 100 | 100 | Cat 5e | 100 | LAN |
5GBASE-T | 802.3bz-2016 | current | 5000 | 4 | 4 | 6.25 | 64B65B PAM-16 128-DSQ | 400 | 200 | 100 | Cat 6 | 250 | LAN |
History[edit]
As faster Wi-Fi protocols such as IEEE 802.11ac were developed, there was significant demand for cheap uplinks faster than 1000BASE-T. These speeds became relevant around 2014 as it became clear that it would not be possible to run 10GBASE-T over already widely deployed Cat5e cable. IEEE 802.3bz also supports power over Ethernet, which had previously not been available at 10GBASE-T.
As early as 2013, the Intel Avoton server processors integrated 2.5 Gbit/s Ethernet ports.
Whilst Broadcom had announced a series of 2.5 Gbit/s transceiver ICs,[10] 2.5 Gbit/s switch hardware was not widely commercially available at that point. Many early 10GBASE-T switches, particularly those with SFP+ interfaces, do not support the intermediate speeds.
In October 2014, the NBASE-T Alliance was founded,[11][12] initially comprising Cisco, Aquantia, Freescale, and Xilinx. By December 2015, it contained more than 45 companies, and aimed to have its specification compatible with 802.3bz.[13] The competing MGBASE-T Alliance, stating the same faster Gigabit Ethernet objectives, was founded in December 2014.[14] In contrast to NBASE-T, the MGBASE-T said that their specifications would be open source.[15] IEEE 802.3's "2.5G/5GBASE-T Task Force" started working on the 2.5GBASE-T and 5GBASE-T standards in March 2015.[16] The two NBASE-T and MGBASE-T Alliances ended up collaborating.[17] with the forming of the IEEE 802.3bz Task Force under the patronage of the Ethernet Alliance in June 2015.
On September 23, 2016, the IEEE-SA Standards Board approved IEEE Std 802.3bz-2016.[18]
References[edit]
- ^ "IEEE P802.3bz 2.5G/5GBASE-T Task Force". IEEE Standards Association.
- ^ "New IEEE P802.3bz Project Achieves Significant Milestone Towards Enabling Higher Speeds Over Installed Base of Twisted Pair Cabling". IEEE Standards Association. Archived from the original on 2017-07-08. Retrieved 2015-11-22.
- ^ "IEEE's 802.3BZ Task Force Mediates MGBASE-T and NBASE-T Alliances". Planetech USA. Archived from the original on 2015-11-22. Retrieved 2015-11-22.
- ^ "Cisco Live BRKCRS-3900, slide 41, time 57:40". Archived from the original on 2016-03-03. Retrieved 2016-01-15.
- ^ Clause 126.7.2 of IEEE 802.3-2018
- ^ Next Generation Enterprise Access BASE-T PHY Objectives
- ^ Maguire, Valerie (2020-06-04). "IEEE Std 802.3ch-2020: Multi-Gig Automotive Ethernet PHY".
- ^ "Cisco Multigigabit Technology". Retrieved 2020-07-30.
- ^ Charles E. Spurgeon (2014). Ethernet: The Definitive Guide (2nd ed.). O'Reilly Media. ISBN 978-1-4493-6184-6.
- ^ "Broadcom Announces New High-Performance Multi-Rate Gigabit PHYs". Archived from the original on 2015-05-29. Retrieved 2015-05-28.
- ^ "Industry Leaders Form NBASE-T Alliance to Promote Multi-Gigabit Ethernet Technology for Enterprise Wired and Wireless Access Networks" (Press release). 2014-10-28. Retrieved 2020-07-30.
- ^ "The NBASE-T Alliance℠". NBASE-T Alliance, Inc. Retrieved 30 December 2015.
- ^ "Oh What a Year!". NBASE-T Alliance, Inc. 2015-12-17. Retrieved 2021-02-04.
- ^ "Open Industry Alliance and IEEE to Bring 2.5G and 5G Ethernet Speeds to Enterprise Access Points" (Press release). Retrieved 2020-07-30.
- ^ "Want 2.5G/5G BASE-T Connections? They're coming". Retrieved 2020-07-30.
- ^ "IEEE 802.3bz Project PAR" (PDF). IEEE 802.3bz Task Force. Retrieved 2015-09-22.
- ^ "IEEE's 802.3BZ Task Force Mediates MGBASE-T and NBASE-T Alliances". Archived from the original on 2015-11-22. Retrieved 2015-11-22.
- ^ "[802.3_NGBASET] FW: Approval of IEEE Std 802.3bz 2.5GBASE-T and 5GBASE-T". IEEE P802.3bz Task Force. Retrieved 2016-09-24.
External links[edit]
- IEEE P802.3bz 2.5G/5GBASE-T Task Force
- NBASE-T Alliance
- MGBASE-T Alliance at the Wayback Machine (archived 2017-11-05)