Wednesday, August 12, 2009

Network Topology and its Types

Network topology is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network, especially the physical (real) and logical (virtual) interconnections between nodes.

Network topologies are categorized into the following basic types:

  • Bus Topology
  • Ring Topology
  • Star Topology
  • Tree Topology
  • Mesh Topology
  • Hybrid Topology

Bus Topology:

In local area networks where bus technology is used, each machine is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the MAC address or IP address on the network that is the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable breaks, the entire network will be down, since there is only one cable.

Advantages of a Linear Bus Topology

  • Easy to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

  • Terminators are required at both ends of the backbone cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution in a large building.


In local area networks where the star topology is used, each machine is connected to a central hub. In contrast to the bus topology, the star topology allows each machine on the network to have a point to point connection to the central hub. All of the traffic which transverses the network passes through the central hub. The hub acts as a signal booster or repeater which in turn allows the signal to travel greater distances. As a result of each machine connecting directly to the hub, the star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding other machines. The primary disadvantage of the star topology is the hub is a single point of failure. If the hub were to fail the entire network would fail as a result of the hub being connected to every machine on the network.

Advantages of a Star Topology

  • Easy to install and wire.
  • No disruptions to the network then connecting or removing devices.
  • Easy to detect faults and to remove parts.

Disadvantages of a Star Topology

  • Requires more cable length than a linear topology.
  • If the hub or concentrator fails, nodes attached are disabled.
  • More expensive than linear bus topologies because of the cost of the concentrators.


In local area networks where the ring topology is used, each computer is connected to the network in a closed loop or ring. Each machine or computer has a unique address that is used for identification purposes. The signal passes through each machine or computer connected to the ring in one direction. Ring topologies typically utilize a token passing scheme, used to control access to the network. By utilizing this scheme, only one machine can transmit on the network at a time. The machines or computers connected to the ring act as signal boosters or repeaters which strengthen the signals that transverse the network. The primary disadvantage of ring topology is the failure of one machine will cause the entire network to fail.


Fully connected
Partially connected

Tree Topology


Advantages of a Tree Topology

  • Point-to-point wiring for individual segments.
  • Supported by several hardware and software venders.

Disadvantages of a Tree Topology

  • More difficult to configure and wire than other topologies.

1 comment:

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