TOPOLOGY:

• Physical structure of the network.
• Shape or map of the network
• Shape or map of the arrangement of nodes in a network.
• It also determines the manner in which information is exchanged within the network.
• A topology defines the arrangement of nodes, cables and connectivity of devices that make us a network.

Type of Topology:

BUS:

• All the devices are connected to a main cable called BUS or Backbone.
• A device called terminator is attached to each end of the cable.
  (to understand the direction of signal and also to absorb the signal)
• Easy to install
• Less cable is required compare to other topology.
• Relatively inexpensive.
• Difficult to troubleshoot and maintain.
• Entire network shutdown if there is a break in the main cable.
• Increasing the number of nodes on the bus, lower the performance.
  (due to collision)
• Only one node can transmit the data at a time.

Advantage: c, d, e
Disadvantage: f, g, h

STAR:

• All nodes are connected to a Hub/Switch.
• The number of nodes can be connected depends on the number of ports of the Hub/Switch.
• Easy to troubleshoot and maintain.
  (If there is a break in cable only one system is down, If there is a failure in Hub/Switch Entire network is down)
• Expensive due to the cost of Hub/Switch.
• Performance of the network depends on the NIC, Cable and Hub/Switch.
  (as they come in various speed)

RING:

• Ring topology is also known as ring network.
• Each node is connected to its neighbors, on both side as a result a loop (ring) is formed.
• Data travels from node to node, with each node handling every packet in one direction (clockwise or anti-clockwise) only.
• Uses token passing technique that allows only one system to transmit data at a time.
  (Token is an empty frame that passes computer to computer, whoever has to send data to other system captures it, add sender & receiver address and data in it.)
• If there is a cable break or node failure, the entire network is shutdown.
• Coaxial cable is used.
• MAU (Multi Access Unit) or MSAU (Multi Station Access Unit) is used to connect the computers.

TREE:

• Also known as hierarchical network.
• A bus topology where branches with multiple nodes are possible.
• It can be used to connect multiple star topologies with each other. If there is a break in main cable, computers on the same star topology would still be able to communicate.

MESH:

• All nodes are connected to every other node to make the network redundant.
• Commonly used in WAN configurations, Routers are connected to multiple links for redundancy and to give the ability to determine the quickest route to a destination.
• It is hybrid as it may include multiple other (different) types of topologies as well.
• It provides a great deal of fault tolerance, as if one link fails other link can be used to transmit the data.

Hybrid Topology:

• A hybrid topology is a combination (mixture) of multiple network topologies.
  Example:
  1. A mixture of Star & Bus  
  2. A mixture of Star, Ring & Bus etc.

Active Topology:

• In an active topology, computers and other devices regenerate the signals and are responsible for moving data through the network.

Passive Topology:

• Computers only listen for data being sent; they are not responsible for moving data from one computer to the next.

Wireless Topology:
Ad Hoc Topology: Two or more computers can communicate directly with one another; sometimes called peer to peer topology
Infrastructure Mode: Use a central device, called an Access Point (AP), to control communications.