TOPOLOGY RING

       Image Topology Ring

A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.

Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link. A node failure or cable break might isolate every node attached to the ring. FDDI networks overcome this vulnerability by sending data on a clockwise and a counterclockwise ring: in the event of a break data is wrapped back onto the complementary ring before it reaches the end of the cable, maintaining a path to every node along the resulting "C-Ring". 802.5 network , also known as IBM Token Ring networks avoid the weakness of a ring topology altogether: they actually use a star topology at the physical layer and a Multistation Acces Unit (MAU) to imitate a ring at the datalink layer.

Many ring networks add a "counter-rotating ring" to form a redunddant topology . Such "dual ring" networks include Spatial Reuse Protocol , Fiber Distribute Data Interface (FDDI), and Resilient Packet Ring .

Advantages 

• Very orderly network where every device has access to the token and the opportunity to transmit.
• Performs better than a star topology under heavy network load.
• Can create much larger network using Token Ring
• Does not require network server to manage the connectivity between the computers

Disadvantages

• One malfunctioning workstation or bad port in the MAU can create problems for the entire network
• Moves, adds and changes of devices can affect the network
• Network adapter cards and MAU's are much more expensive than Ethernet cards and hubs
• Much slower than an Ethernet network under normal load