2.5GBASE-T and 5GBASE-T
IEEE 802.3bz, NBASE-T and MGBASE-T refer to standards for Ethernet over twisted pair at speeds of 2.5 Gbit/s and 5 Gbit/s. These represent intermediate speeds between Gigabit Ethernet and 10 Gigabit Ethernet, potentially allowing for faster speeds over existing cabling. The resulting standards are named 2.5GBASE-T and 5GBASE-T.[1][2][3] They are both specified in Clauses 125 and 126 of the current IEEE 802.3 standard.
Technology[edit]
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 transfer rate 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, Cat 6, and Cat 6A cables.[5]
Power over Ethernet[edit]
Unlike the preceding 10GBASE-T standard, equipment manufacturers have indicated their intention to implement 802.3at type Power over Ethernet on certain types of NBASE-T switches. This implementation is intended to support high-bandwidth wireless access points (802.11ac / 802.11ax) which exceed the speed capabilities of 1000BASE-T.[6]
Comparison of twisted pair based Ethernet technologies[edit]
| Name | Speed[A] (Mbit/s) | Lanes per direction | Bits per cycle | Spectral bandwidth (MHz) | Required cable[B] | Cable rating (MHz) |
|---|---|---|---|---|---|---|
| 10BASE-T | 10 | 1 | 1 | 10 | Cat 3 | 16 |
| 100BASE-TX | 100 | 1 | 3.2 | 31.25 | Cat 5 | 100 |
| 1000BASE‑T | 1,000 | 4 | 4 | 62.5 | Cat 5 | 100 |
| 2.5GBASE-T | 2,500 | 4 | 6.25 | 100 | Cat 5e | 100 |
| 5GBASE-T | 5,000 | 4 | 6.25 | 200 | Cat 6 | 250 |
| 10GBASE-T | 10,000 | 4 | 6.25 | 400 | Cat 6A | 500 |
- ^ Transfer speed = lanes × bits per hertz × spectral bandwidth
- ^ At shorter cable length, it is possible to use cables of a lower grade than what is required for 100 m. For example, it is possible to use 10GBASE-T on a Cat 6 cable of 55 m or less. Likewise, 5GBASE-T is expected to work with Cat 5e in most use cases.
History[edit]
The intermediate speeds became relevant around 2014 as it became clear that it would not be possible to run 10GBASE-T over the Cat5e cable that had been used for the wiring in many buildings but that, with the development of fast WiFi protocols such as IEEE 802.11ac, there was a significant demand for cheap uplink faster than 1000BASE-T offered. IEEE 802.3bz will also support Power over Ethernet, which has generally 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,[7] 2.5 Gbit/s switch hardware was not widely commercially available at that point; 10GBASE-T switches do not generally support the intermediate speeds.
In October 2014, the NBASE-T Alliance was founded,[8] initially comprising Cisco, Aquantia, Freescale, and Xilinx. By May 2015,[9] it had expanded to 34 members covering most producers of networking hardware.
The competing MGBASE-T Alliance, stating the same faster Gigabit Ethernet objectives, was founded in December 2014.[10] In contrast to NBASE-T, the MGBASE-T says that their specifications will be open source.[11]
IEEE 802.3's "2.5G/5GBASE-T Task Force" started working on the 2.5GBASE-T and 5GBASE-T standards in March 2015.[12]
The two NBASE-T and MGBASE-T Alliances ended up collaborating.[13] 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.[14]
NBASE-T Alliance[edit]
The NBASE-T Alliance was founded in 2014 by Aquantia Corporation, Cisco Systems, Freescale Semiconductor, and Xilinx.[15] It now consists of more than 45 companies, and it aims to have its specification compatible with 802.3bz.[16]
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.
- ^ "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
- ^ "Cisco Multigigabit Technology". Retrieved 2020-07-30.
- ^ "Broadcom Announces New High-Performance Multi-Rate Gigabit PHYs".[dead link]
- ^ "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.
- ^ "NBASE-T Alliance Jumps to 34 Members" (Press release). 2015-05-14. Retrieved 2020-07-30.
- ^ "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.
- ^ "The NBASE-T Alliance℠". NBASE-T Alliance, Inc. Retrieved 30 December 2015.
- ^ "Oh What a Year!". NBASE-T Alliance, Inc. 2015-12-17. Retrieved 30 December 2015.