C.3. AUI Port Concentrator

Although it isn't described in the Ethernet standard, the AUI port concentrator (shown in Figure 3.3), also called a port multiplier , transceiver multiplexor, or fan out unit, is widely used in older 10 Mbps Ethernet systems.

The original port concentrator was developed by DEC and called the DELNI (for Digital Ethernet Local Network Interconnect). Port concentrators sold by other vendors are often referred to as DELNIs or called "DELNI-like" devices. The port concentrator was developed when thick coaxial Ethernet was the only media type available, and network designers faced a problem when it came to connecting a set of machines clustered together in a small space.