The physical layout of devices on a network and how the cables and wires connect these devices.
How data is transmitted and received between devices on a network regardless of their physical connections.
Physical Bus topology
All nodes are connected to a single backbone. The backbone is a single wire that carries data packets to the nodes. Terminators must be installed at the two ends of the backbones.
Disadvantages of Bus Topologies
Unable to accommodate a large number of nodes - such as those required for LAN's
A single break in the backbone disables the entire network
Physical Ring topology
Each node connects to exactly two other nodes, forming a complete ring, which generally circulates data packets in one direction. Each node receives data from one node and transmits to the other.
Advantages of Ring Topologies
There are dirty jokes that can be made about it...If you're feeling particularly inventive.
Disadvantages of Ring Topologies
If one cable is broken the entire network is disabled
To remove or add a node, the entire network must be stopped
All nodes must be powered at all times if the network is to operate
These include more than one physical path between pairs of nodes. Routers are required for mesh topologies.
Advantage of Mesh Topologies
Fault tolerance, as packages are automatically routed around faults.
Can be used in high-speed long distance connections
Physical Star Topology
All nodes connect to a central node via their own dedicated cable.The central node is the device that connects all outlying nodes such that they can transmit and receive packets to and from each other node.
Advantages of Star Topologies
Each node had its own cable and can be connected and disconnected without affecting any other nodes
New nodes can be easily added without first disabling the network
The process of identifying faults is made more simple
Disadvantages of Star Topologies
A lot of cabling is required
If a fault occurs in the central node then all connected nodes are also disabled
Physical Hybrid Topology
Also known as tree topologies. These use a combination of connected bus, star and ring topologies.