Network Topologies

Point-to-Point Topology

• Point-to-point (PTP) topology connects two nodes directly together. The following examples are pure point to point links:

• Two computers communicating via modems.

• A mainframe terminal communicating with a front end processor.

• A workstation communicating along a parallel cable to a printer.

Star Topology

• The star topology is a popular method of connecting the cabling in a computer network. In a star, each device connects to a central point via a point-to-point link. Depending on the locical architecture used, several names are used for the central point includeing the following:

• Hub

• Multipoint Repeater

• Concentrator

• Multi-Access Unit (MAU)

Ring Topology

• The Ring Topology is a physical, closed loop consisting of point-to-point links. In the diagram you can see how each node on the ring acts as a repeater. It receives a transmission from the previous node and amplifies it before passing it on.

Bus Topology

• In a Bus topology, all devices attach to the same transmission medium. The medium has a physical beginning and end.All buses are implemented using electrical cable, usually coax, and the ends of the cable must be terminated with a terminating resistor that matches the impedance of the cable. The terminating resistor prevents data reflections from coming across as data corruption. The bus is considered a multipoint system because all devices tap into the same backbone cable.

Hybrid Topology

• The Hybrid topology scheme combines multiple topologies into one large topology. The hybrid network is common in large wide area networks. Because each topology has its own strengths and weaknesses, several different types can be combined for maximum effectiveness.

Coaxial Cable

UTP Cable

Ethernet

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

Token Ring

• The adjacent figure shows the path that a transmission follows through the network. Starting at the hub, the signal travels through a pair of wires to the receive circuits 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.

ARCnet

• ARCnet is wired in a star using coaxial cable. The diagram adjacent shows an extremely simple ARCnet using a single passive hub.