Topologies of Common Networks

As mentioned earlier, a network can have a logical topology different from its physical topology. The following are some common types of networks:

• Ethernet
• Token Ring.

1. Ethernet

An older, common wiring system for Ethernet (10Base2) and (10Base5) uses coaxial cable in a linear bus topology. In the most type of Ethernet, each node connects to the coax through a T-connector that taps into the signals on the coaxial cable. The nodes both transmit and receive through connector. Therefore, 10Base2 Ethernet is a logical as well as a physical bus.

A newer variation of Ethernet, 10Base-T and 100Base-TX, are cabled using wiring hubs (concentrators). Each station is connected to the hub via an individual UTP twisted pair cable. Within the hub, however, the individual signals are combined into a bus. Therefore 10Base-T and 100Base-TX are physical stars,but logical buses.

2. Token Ring

In the wiring of a Token Ring, it meets all the specifications of a star. Token Ring uses central wiring hubs and each node is wired to the hub with an individual run of cable.

Starting at the hub, the signal travels through a pair of wires to the receive circuit on the node's network interface. The receive circuit passes the signal to the transmit circuit, which repeats the signal on a separate pair of wires and sends the signal back to the hub.

If there is signal around the entire network, it completes a circuitous path, proving that Token Ring has a ring logical topology.

Token ring is wired in a physical star to obtain the advantages of a central wiring hub. All stations can be connected and disconnected at a central point and the wiring hub can be equipped with hub management and diagnostic systems. Sometimes Token Ring referred as a star-wired-ring.