Network topology is the map that defines how network devices connect each other. Topologies define the structure of the network. There are two types of topology definition :
Logical Topology
Logical topologies define the method used for accessing the media. Most common logical topologies are broadcast and token-passing.
Physical Topology
Physical topologies defines the current design of the cable ( media ). These topologies are Bus, Ring, Star, Extended Star, Hierarchical and Mesh.
Bus Topology :
There is a cable on each end points that have a determinator. Bus topology is one of the first application type of the ethernet. It is easy that connecting to a PC or interface to a linear bus, this topology requires less cable than star topology but if the main cable is down, all network is down too. Bus topology requires terminators on cable end points. It is hard to troubleshoot because of all network is down if main cable is down. It is not offered on large scale areas.
Ring Topology :
Ring topology is created by connecting each network device like a ring. Last network device should be connected to first one to create the ring. Most common ring topologies are Token Ring ve FDDI.
Star Topology :
Star topology is created by connecting each node to a central network device like a switch , hub or etc. Cabling and installation of star topology is easy. There is no interruption when you plug a device to the network. Troubleshooting is easy also on star topology. Disadvantage of this topology is that if the switch or hub is down, whole network is down too.
Extended Star Topology :
Extended Star topology is created by combining more than one star topology networks. That provides expansion for network’s distance and area.
Full Mesh Topology :
Full mesh topology is the most common topology for buildings that requires no interruption. This topology requires lots of cabling and because of that it is expensive. All devices are connected each other with many cables.
Partial Mesh Topology :
Partial mesh topology is a small form of the full mesh topology. Most of the devices are connected each other with many cables.