35. network topology

• Describe the three basic types of topology used in networks.

  • There are, in general, three different types of network topologies, namely, bus, ring, and star.

  • Bus topology:

    • all devices share a common medium

    • one device transmits, all of the other devices receive the transmission

    • Ethernet local area network (LAN) -- most common bus network

  • Ring topology:

    • interconnects nodes via series point-to-point links that form a ring

    • each system has a pair of connections: one inbound and one outbound (device A connected to device B; device B to device C; device C back to device A.)

    • When a device transmits, the other devices receive the transmission in the order that they are attached in the ring (e.g., A to B to C)

    • the transmission delay can be up to several seconds in very large rings.

    • The IBM Token Ring LAN and Fiber Distributed Data Interface (FDDI) metropolitan area network (MAN) were the most common ring topology networks; neither is in common use today.

  • Star topology:

    • interconnects the devices via point-to-point links between the device and a central switch.

    • The central switch or hub is responsible for receiving a transmission and then forwarding to the appropriate receiver.

    • Most networks today, from LANs to wide area networks, employ a physical star topology.