Ethernet

Ethernet came into being in the 1970s and gradually emerged as the indispensable technology for local networks, of which it currently has 90% of the market. It connects workstations to company servers, campuses and institutions. Ethernet Gigabit technology appeared in 1998. A year later it began to replace ATM as the level 2 protocol on distribution networks.

Computers in a network fitted with a suitable card are connected, depending on the Ethernet version adopted,using coaxial cables, optical fibres or copper telephone wire.

Today dedicated mode Ethernet connections have made collision avoidance mechanisms obsolete and have allowed a tenfold increase in the maximum rate of a protocol for which new specifications have been standardised. As a result, the latest versions of Ethernet have big advantages, especially for backbones and metropolitan area networks (MAN).

Among the major benefits of Ethernet technology are:

* The encapsulation of the IP protocol by Ethernet technology is very well established since its generalised use in local network environments.

* The technology is well understood by network administrators who can manage their WAN (wide area network) as a vast Ethernet LAN (local area network).

* It offers very fine rate quantisation, of the order of a megabit per second (Mbit/s). It is therefore possible to start with a 100Mbit/s interface and a rate of 10Mbit/s, then gradually increase the access rate according to need.

The success of Ethernet now rests on a still closer complementarity between this technology and the IP services, and on its effective adaptation in the heart of the network. The 802.17 (RPR, Resilient Packet Ring) standard is supported by Cisco and Nortel and was approved in 2003. This link protection and restoration technology gives Ethernet networks over fibre/DWDM (Dense Wavelength Division Multiplexing) the robustness of Sonet networks. It helps to optimise resources and provide good resilience to breakdowns.