Prerequisite – Gigabit Ethernet
802 committee was asked by IEEE to start on 10-Gigabit Ethernet. The work pattern was the same as the previous Ethernet standards. 10 Gbps is a truly great speed, 1000 times faster than the original Ethernet. It could be needed inside data centres and exchanges to connect high-end routers, switches, and servers, as well as in long-distance, high bandwidth trunks between offices that are enabling entire area networks based on Ethernet and fibre. The short-distance connections may use copper or fibre, while the long connections may use optical fibre.
10-gigabit Ethernet supports the only full-duplex operation. They concentrate on the details of physical layers that can run at very high speed. CSMA/CD is no more a part of 10-gigabit Ethernet. Compatibility still matters, though, so 10-gigabit Ethernet interfaces auto-negotiate and fall back to the highest speed supported by both ends of the line.
The main kinds of 10-gigabit Ethernet are listed in the table below. Multimode fibre with the 0.85µ (short) wavelength is used for medium distances, and single-mode fiber at 1.3µ (long) and 1.5µ (extended) is used for long distances. To make it suitable for wide-area applications, one can use 10GBase-ER which can run for distances of 40 km. All the versions of 10-gigabit Ethernet send a serial stream of information that is produced by scrambling the data bits, then encoding them with a 64B/66B code.
Table : 10-Gigabit Ethernet Cabling
|10GBase-SR||Fiber Optics||Up to 300 m||Multimode fiber (0.85µ)|
|10GBase-LR||Fiber Optics||10 km||Single-mode fiber (1.3µ)|
|10GBase-ER||Fiber Optics||40 km||Single-mode fiber (1.5µ)|
|10GBase-CX4||4 pairs of twinax||15 m||Twinaxial copper|
|10GBase-T||4 pairs of UTP||100 m||Category 6a UTP|
10GBase-CX4 was the first copper version defined. It uses a cable with four pairs of twin axial copper wiring. It runs at 3.125 Gsymbols/second to reach 10 Gbps. This version of copper is cheaper than fibre but whether it will beat out in the long run by 10-gigabit Ethernet over more garden variety twisted pair wiring.
UTP cables were used in 10GBase-T. Not surprisingly, the physical layer is quite involved o reach 10 Gbps over twisted pair. To send 2500 Mbps in both directions each of the four twisted pairs is used. This speed can be reached using a signalling rate of 800 Msymbols/sec with symbols that use 16 voltage levels. To standardize Ethernet operating at 40Gbps and 100 Gbps IEEE created a group. Proprietary products are already available but the standard is not yet complete.
Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.