Network Topology Network topology is the arrangement of the various elements of a communication network. It is the topological structure of a network and may be depicted physically or logically. Physical topology is the placement of the various components of a network, including device location and cable installation. Logical topology illustrates how data flows within a network.
Different network topologies
Point-to-point The simplest topology with a dedicated link between two endpoints. Using circuit-switching or packetswitching technologies, a point-to-point circuit can be set up dynamically. It is extremely simple to set up.
Bus Topology A bus network topology is the one in which nodes are directly connected to a common linear half-duplex link called a bus. A host on a bus network is called a Station or workstation. In a bus network, every station will receive all network traffic, and the traffic generated by each station has equal transmission priority.
Bus Network Topology
Advantages Very easy to connect a computer or peripheral to a linear bus Requires less cable length than a star topology resulting in lower costs It works well for small networks It is easy to extend by joining cable with connector or repeater If one node fails, it will not effect the whole network Disadvantages Entire network shuts down if there is a break in the main cable or one of the T-connectors break Large amount of packet collisions on the network, which results in high amounts of packet loss Slow with many nodes in the network
STAR TOPOLOGY A star network consists of one central hub which is used to transmit messages to various hosts. Every host is connected to a central hub. The hub, hosts and the transmission lines between them, form a graph with the topology of a star. Data on a star network passes through the hub before continuing to its destination.
The hub manages and controls all functions of the network. It also acts as a repeater for the data flow. The star topology reduces the impact of a transmission line failure by independently connecting each host to the hub. Each host may thus communicate with all others by transmitting to, and receiving from, the hub. The failure of a transmission line linking any host to the hub will result in the isolation of that host from all others, but the rest of the network will be unaffected. The star configuration is commonly used with twisted pair cable and optical fiber cable. However, it can also be used with coaxial cable.
Star Network Topology
Advantages If one node or its connection breaks it doesn t affect the other computers and their connections. Devices can be added or removed without disturbing the network. Disadvantages An expensive network layout to install because of the amount of cables needed The central hub is a single point of failure for the network.
Ring Topology 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. Rings can be unidirectional or bidirectional. As Ring topology provides only one pathway between any two nodes, unidirectional 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.
Ring Network Topology
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 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
Tree Topology A tree network, or star-bus network, is a hybrid network topology in which star networks are interconnected via bus networks. Tree networks are hierarchical, and each node can have an arbitrary number of child nodes. It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.
Tree Network Topology