Networks
Different types of networks
Bus Network
The illustration shows a ring network with five nodes. Each node is shown as a sphere, and connections are shown as straight lines. The connections can consist of wired or wireless links.
The ring topology may prove optimum when system requirements are modest and workstations are at scattered points. If the workstations are reasonably close to the vertices of a convex polygon (such as the pentagon shown in the illustration), the cost can be lower than that of any other topology when cable routes are chosen to minimize the total length of cable needed.
A break in the cable of a ring network may result in degraded data speed between pairs of workstations for which the data path is increased as a result of the break. If two breaks occur and they are not both in the same section of cable, some workstations will be cut off from some of the others. When system reliability is a critical concern, a bus network or star network may prove superior to a ring network. If redundancy is required, the mesh network topology may be preferable.
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 travel 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.[1] A node failure or cable break might isolate every node attached to the ring. In response, some ring networks add a "counter-rotating ring" (C-Ring) to form a redundant topology: in the event of a break, data are wrapped back onto the complementary ring before reaching the end of the cable, maintaining a path to every node along the resulting C-Ring. Such "dual ring" networks include Spatial Reuse Protocol, Fibre Distributed Data Interface (FDDI), and Resilient Packet Ring. 802.5 networks - 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 media access unit (MAU) to imitate a ring at the data link layer.
Star Network
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central 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 a central node called a 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. If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems.
The star topology reduces the damage caused by line failure by connecting all of the systems to a central node. When applied to a bus-based network, this central hub rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, sometimes including the originating node. All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected.
It is also designed with each node (file servers, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator.
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable. However, it can also be used with coaxial cable or optical fibre cable.