Bus, Star, Tree, Ring, Mesh & More complex networks can be built as hybrids of two or more of the above basic topologies.
Bus network uses a common backbone to connect all devices. The backbone functions as a shared communication medium that devices attach into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
However, bus networks works best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.
Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN.
Tree topologies integrate multiple star topologies together onto a bus. Hub devices connect directly to the tree and each hub functions as the root of a tree of devices. This bus/ star hybrid approach supports future expandability of the network much better than a bus or a star alone.
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction .A failure in any cable or device breaks the loop and can take down the entire network.
To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. Partial mesh networks also exist in which some devices connect only indirectly to others.