components of a network

A ring, a star and a bus network

A ring network


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 by sending data in 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".



Advantages

  • Very orderly network where every device has access to the token and the opportunity to transmit
  • Performs better than a bus topology under heavy network load
  • Does not require a central node to manage the connectivity between the computers
  • Due to the point to point line configuration of devices with a device on either side (each device is connected to its immediate neighbour), it is quite easy to install and reconfigure since adding or removing a device requires moving just two connections.
  • Point to point line configuration makes it easy to identify and isolate faults.

Disadvantages

  • One malfunctioning workstation can create problems for the entire network. This can be solved by using a dual ring or a switch that closes off the break.
  • Moving, adding and changing the devices can affect the network
  • Communication delay is directly proportional to number of nodes in the network
  • Bandwidth is shared on all links between devices
  • More difficult to configure than a Star: node adjunction ⇨ Ring shutdown and reconfiguration



a star network

Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages. This consists of a central node, to which all other nodes are connected; this central node provides a common connection point for all nodes through a hub. In Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch. The switch is the server and the peripherals are the clients. Thus, the hub and leaf nodes, and the transmission lines between them, form a graph with the topology of a star.



Advantages

Better performance: star topology prevents the passing of data packets through an excessive number of nodes. At most, 3 devices and 2 links are involved in any communication between any two devices. Although this topology places a huge overhead on the central hub, with adequate capacity, the hub can handle very high utilization by one device without affecting others.

Isolation of devices: Each device is inherently isolated by the link that connects it to the hub. This makes the isolation of individual devices straightforward and amounts to disconnecting each device from the others. This isolation also prevents any non-centralized failure from affecting the network.

Benefits from centralization: As the central hub is the bottleneck, increasing its capacity, or connecting additional devices to it, increases the size of the network very easily. Centralization also allows the inspection of traffic through the network. This facilitates analysis of the traffic and detection of suspicious behavior.

• Easy to detect faults and to remove parts.

• No disruptions to the network when connecting or removing devices.

• Installation and configuration is easy since every one device only requires a link and one input/output port to connect it to any other device(s).


Disadvantages

• High dependence of the system on the functioning of the central hub. Failure of the central hub renders the network inoperable



a bus network

A bus network topology is a network architecture in which a set of clients are connected via a shared communications line/cables, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers. Bus networks are the simplest way to connect multiple clients, but may have problems when two clients want to transmit at the same time on the same bus. Thus systems which use bus network architectures normally have some scheme of collision handling or collision avoidance for communication on the bus.


Advantages

  • Ease of installation.
  • Simple and cheap.
  • If one computer fails it does not affect the other computers.
  • Printers can be shared.
Disadvantages
  • If the main cable fails, all the other sources will die
  • Reconfiguration, fault isolation and installation of new devices tend to be difficult since the network is designed to be most efficient during installation.
  • The longer the distance covered by a signal along the shared communication line the greater the heat is produced due to energy being transformed to heat making the signal weaker the farther it travels. A fault along the shared communication line stops all transmissions in the network.
  • Connection Limitation can also occur


created by - james dolphin 10g