25 Gigabit Ethernet

History

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

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

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

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). The IEEE 802.3by standard defines:

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

50 Gigabit Ethernet

The IEEE P802.3cd task force is working with the objectives to define single-lane 50 Gbit/s PHYs for operation over:

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, 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, 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.

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