PC's are formed into a logical ring with each PC connected to at least two other PC's. The ring is a closed system and is shown in the diagram below. It is important to realize that the PC's do not have to be physically placed around in a ring. It is how they are connected which leads to the ring not there actual physical positions. A bus network can send a packet in either direction (or both!) whilst a ring network the packet will only travel in one direction. The direction that the packet travels is shown on the diagram below.

Ring networks benefit from the fact that there are no collisions which will occur on the network. As packets only go one way around the network then there will be no situation where two packets are traveling towards one another. Also when a packet arrives at its destination it is removed from the network, so will no longer travel around the ring. If the packet was a broadcast packet, that is meant for all PC's, then it would be the sender who removes the packet. In fact if the packet is incorrectly addressed then the sender can remove the packet from the network and will also know that there is a issue with the sending of that packet.

In order for a ring network to work it is necessary that only one PC transmits packets at a given time. This is done by using a token which is passed around from PC to PC. A PC can only send data when it has the token. Once it has finished, or it has held the token for a given amount of time, then the token is passed on. That way every PC will get a chance to send packets at some point. When the token arrives at a PC which does not need to send any packets then it will simply just pass the token on. This is known as a token ring network,

Advantages

• No collisions
• PC can make 100% of the available band width when sending packets
• Token ring networks perform faster than bus networks for small numbers of PC's

Disadvantages

• PC's can wait a while in order to send packets. This time increases the more PC's which are added to the network.
• If a cable breaks or a NIC is damaged then the ring is broken and no packets can be sent.
• Performs badly if there are too many PC's attached to the network.