Networking —

IEEE 802.3 Standards

The IEEE 802.3 standards define a range of networking systems that are based on the original Ethernet standard. The variations include speed, physical topology, and implementation considerations. The following sections describe these standards.

10 Mbps Networking Standards

There is no specific designation called 'standard Ethernet,' but if there were, it would be assigned to the 10Mbps variants of the IEEE 802.3 standards. Although 10Mbps is now considered too slow for most new networks, there are a large number of existing networks operating at 10Mbps. A number of 10Mbps standards exist, with 10BaseT now being the most common. In the following sections, we discuss a number of the 10Mbps standards.

10Base2

10Base2, which is defined as part of the IEEE 802.3a standard, specifies data transmission speeds of 10Mbps and a total segment length of 185 meters using RG-58 coaxial cable. The 10Base2 standard specifies a physical bus topology and uses BNC connectors with 50-ohm terminators at each end of the cable. One of the physical ends of each segment must be grounded.

10Base2 networks allow a maximum of five segments with only three of those segments populated. Each of the three populated segments can have a maximum of 30 nodes attached. 10Base2 requires that there is a minimum of .5 meters between nodes. For the network to function properly, the segment must be complete. With this in mind, the addition or removal of systems might make the network unusable.

10BaseT

The 10BaseT standard is another 10Mbps standard using UTP cabling. 10BaseT networks have a maximum segment length of 100 meters, and up to a total of five physical segments per network.

10BaseT networks use a star topology with a point-to-point connection between the computer and the hub or switch. 10BaseT can use different categories of UTP cabling, including 3, 4, 5. It can also be used with category 5e and category 6 cabling, but that is a little like renting the Daytona speedway for the day and then cycling around it.