here i attach some information about computer science since i am computer science's student... hope this information useful... ^_^

Bus Network Topology

 

Bus Network Topology.

Bus networks share a common connection that extends to all devices. This network topology is used in small networks, and it is simple to understand. Every computer and network device connects to the same cable, so if the cable fails, the whole network is down, but the cost of setting up the network is reasonable.This type of networking is cost effective. However, the connecting cable has a limited length, and the network is slower than a ring network.

Ring Network Topology

Ring Network Topology.

Each device in a ring network is attached to two other devices, and the last device connects to the first to form a circular network. Each message travels through the ring in one direction—clockwise or counterclockwise—through the shared link. Ring topology that involves a large number of connected devices requires repeaters. If the connection cable or one device fails in a ring network, the whole network fails.Although ring networks are faster than bus networks, they are more difficult to troubleshoot.

Star Network Topology

 

Star Network Topology.

A star topology typically uses a network hub or switch and is common in-home networks. Every device has its own connection to the hub. The performance of a star network depends on the hub. If the hub fails, the network is down for all connected devices. The performance of the attached devices is usually high because there are usually fewer devices connected in star topology that in other types of networks.A star network is easy to set up and easy to troubleshoot. The cost of setup is higher than for bus and ring network topology, but if one attached device fails, the other connected devices are unaffected.