100GBASE

100GBASE refers to a family of Ethernet physical layer specifications that define how 100 gigabits per second can be transmitted over various media. The standards are overseen by IEEE 802.3 and began with 802.3ba in 2010, with later amendments adding additional media types and reach options. 100GBASE denotes not a single interface but a range of related interfaces that share the same 100 Gbps data rate.

In fiber deployments, the most common variants are 100GBASE-SR4, 100GBASE-LR4, and 100GBASE-ER4. SR4 uses four parallel 25 Gbps channels over multimode fiber with a 850 nm light source, typically using an MPO/MTP connector for short-reach links. LR4 and ER4 use four 25 Gbps channels carried over single-mode fiber with wavelength-division multiplexing; LR4 supports moderate distances, while ER4 supports longer distances.

There is also 100GBASE-CR4, which uses four 25 Gbps copper channels over twinaxial cable for short, intra-data-center links, typically via QSFP28 interfaces.

Interoperability and use: 100GBASE interfaces require corresponding 100 Gbps transceivers and switch or router ports that implement the 100GBASE PHY. They are used in metro, data center, and high-performance computing networks, often in conjunction with 40G and 400G Ethernet upgrades. The standard supports forward error correction and various encoding schemes to balance bandwidth and signal integrity.