Ethernet Hardware

Ethernet has developed over time. There version 2 released in 1982 was initially developed through Xerox- Intel-Dec. Within 1985 the IEEE released a new standard for ethernet. This standard is named IEEE 802.2. In common, these two versions of ethernet can inter-operate; thus there are a few minor differences. The first difference is in which the ethernet packet header Version 2 defined a two byte Type field although IEEE created a 2 byte length field in which location. Fortunately, values for category cannot conflict with valid length values and most systems can determine the Ethernet Frame type through examining this field. A second difference is in which the Ethernet version 2 specifications needs in which a transceiver send a heartbeat signal every second. The IEEE 802.2 specification removed this. This has resulted in most vendors offering transceivers in which have a switch to enable or disable heart-beat. Ethernet should be off unless connected to a piece of equipment using the ethernet version 2 specifications. Fortunately, all new devices are built to conform to the 802.2 specification. Though, occasionally devices are found in which were installed years ago which still required this.

In other specification, an ethernet uses a 48-bit identifier to uniquely recognize every source and destination device. A range of addresses is assigned to each manufacturer of ethernet equipment.

There are generally two types of ethernet elements, one category which passes the signal onto other devices, commonly these are known as repeaters. Second categories of device that takes the signal and regenerates the signal onto a new network, these categories of devices are commonly known as bridges or routers. The Repeaters are useful for propagating a network signal, a signal comes in on an input port is frequently output to several ports. However, because they add a few delays to the transmittal of packets they decrease the maximum size of a segment. Thus, repeaters can make simpler the design of a network.

Devices like as bridges and routers, that reproduce the signal, permit to build larger networks. Because the signal is reproduce, it becomes the responsibility of the bridge or router to guarantee the packets arrival at the destination (or the next router or bridge). The Bridges and routers work at various levels of the network. Bridges work at the ethernet frame level although routers work at the protocol level. In cases, the bridge or router has the property of filtering traffic and only transmitting the signal onto networks. Therefore, in each case they have the effect of decreasing unnecessary traffic.