10-gigabit Ethernet

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10-gigabit Ethernet (XGbE or 10GbE) is the most recent (as of 2005) and fastest of the Ethernet standards. It defines a version of Ethernet with a nominal data rate of 10 Gbit/s, ten times faster than gigabit Ethernet. It is currently specified by a supplementary standard, IEEE 802.3ae, and will be incorporated into a future revision of the IEEE 802.3 standard.

The new 10 gigabit Ethernet standard encompasses seven different media types for LAN, MAN and WAN.

There are a number of different physical layer (PHY) standards. The letter "X" denotes 8B/10B signal encoding and is used for copper interfaces. The most common optical variety is referred to as LAN PHY, used for connecting directly between routers and switches. Although called LAN, this can be used with 10GBase-LR and -ER up to 80 km. LAN PHY uses a line rate of 10.3 Gbit/s and a 66B encoding. WAN PHY (denoted by a "W") encapsulates Ethernet frames for transmission over a SDH/SONET STS-192c channel.

10GBASE-SR ("short range") — designed to support short distances over deployed multi-mode fiber cabling, it has a range of between 26 m and 82 m depending on cable type. It also supports 300 m operation over a new 2000 MHz·km multi-mode fiber (using 850 nm).
10GBASE-CX4 — Copper interface using InfiniBand CX4 cables and InfiniBand 4x connectors for short-reach (15 m maximum) applications (such as aggregation switch to router). This is currently the lowest-cost per port interface at the expense of transmission range.
10GBASE-LX4 — uses wavelength division multiplexing to support ranges of between 240 m and 300 m over deployed multi-mode cabling. Also supports 10 km over single-mode fiber. Uses wavelengths around 1310 nm.
10GBASE-LR ("long range") — this standard supports distances of up to 10 km over single-mode fiber (using 1310 nm).
10GBASE-ER ("extended range") — this standard supports distances up to 40 km over single-mode fiber (using 1550 nm). Recently several manufacturers have introduced 80-km-range ER pluggable interfaces.
10GBASE-LRM [1] — this standard will support distances up to 220 m 10 Gbit/s on FDDI-grade 62.5 µm multi-mode cable.
10GBASE-SW, 10GBASE-LW and 10GBASE-EW — These varieties use the WAN PHY, designed to interoperate with OC-192/STM-64 SDH/SONET equipment using a light-weight SDH/SONET frame. They correspond at the physical layer to 10GBASE-SR, 10GBASE-LR and 10GBASE-ER respectively, and hence use the same types of fiber and support the same distances. (There is no WAN PHY standard corresponding to 10GBASE-LX4.)

Unlike earlier Ethernet systems, 10 gigabit Ethernet (for any nontrivial distance) is so far based mostly on the use of optical fiber connections (with the exception of -CX4). However, the IEEE is developing a standard for 10 gigabit Ethernet over twisted pairs (10GBASE-T), using Cat-6A cable and planned for approval in 2006. Additionally, this developing standard is moving away from half-duplex design, with broadcasting to all nodes, towards only supporting switched full-duplex networks. It is claimed that this system has high compatibility with earlier Ethernet and IEEE 802.3 networks.

10 gigabit Ethernet is very new, and it remains to be seen which of the standards will gain commercial acceptance.

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