Network topologies describe the ways in which the elements of a network are connected. They describe the physical and logical arrangement of network nodes. Let us look at the advantages different network topologies offer, and their shortfalls. Advantages and Disadvantages of...

• Bus Topology
• Ring Topology
• Mesh Topology
• Star Topology
• Tree Topology
• Hybrid Topology

Advantages ▸ It is easy to set up, handle, and implement. ▸ It is best-suited for small networks. ▸ It costs very less. Disadvantages ▸ The cable length is limited. This limits the number of network nodes that can be connected. ▸ This network topology can perform well only for a limited number of nodes. When the number of devices connected to the bus increases, the efficiency decreases. ▸ It is suitable for networks with low traffic. High traffic increases load on the bus, and the network efficiency drops. ▸ It is heavily dependent on the central bus. A fault in the bus leads to network failure. ▸ It is not easy to isolate faults in the network nodes. ▸ Each device on the network "sees" all the data being transmitted, thus posing a security risk. Advantages ▸ The data being transmitted between two nodes passes through all the intermediate nodes. A central server is not required for the management of this topology. ▸ The traffic is unidirectional and the data transmission is high-speed. ▸ In comparison to a bus, a ring is better at handling load. ▸ The adding or removing of network nodes is easy, as the process requires changing only two connections. ▸ The configuration makes it easy to identify faults in network nodes. ▸ In this topology, each node has the opportunity to transmit data. Thus, it is a very organized network topology. ▸ It is less costly than a star topology. Disadvantages ▸ The failure of a single node in the network can cause the entire network to fail. ▸ The movement or changes made to network nodes affect the entire network's performance. ▸ Data sent from one node to another has to pass through all the intermediate nodes. This makes the transmission slower in comparison to that in a star topology. The transmission speed drops with an increase in the number of nodes. ▸ There is heavy dependency on the wire connecting the network nodes in the ring. Advantages ▸ The arrangement of the network nodes is such that it is possible to transmit data from one node to many other nodes at the same time. ▸ The failure of a single node does not cause the entire network to fail as there are alternate paths for data transmission. ▸ It can handle heavy traffic, as there are dedicated paths between any two network nodes. ▸ Point-to-point contact between every pair of nodes, makes it easy to identify faults. Disadvantages ▸ The arrangement wherein every network node is connected to every other node of the network, many connections serve no major purpose. This leads to redundancy of many network connections. ▸ A lot of cabling is required. Thus, the costs incurred in setup and maintenance are high. ▸ Owing to its complexity, the administration of a mesh network is difficult. Advantages ▸ Due to its centralized nature, the topology offers simplicity of operation. ▸ It also achieves isolation of each device in the network. ▸ Adding or removing network nodes is easy, and can be done without affecting the entire network. ▸ Due to the centralized nature, it is easy to detect faults in the network devices. ▸ As the analysis of traffic is easy, the topology poses lesser security risk. ▸ Data packets do not have to pass through many nodes, like in the case of a ring network. Thus, with the use of a high-capacity central hub, traffic load can be handled at fairly decent speeds. Disadvantages ▸ Network operation depends on the functioning of the central hub. Hence, central hub failure leads to failure of the entire network. ▸ Also, the number of nodes that can be added, depends on the capacity of the central hub. ▸ The setup cost is quite high. Imagine a hierarchy of network nodes, with the root node serving client nodes, that in turn serve other lower-level nodes. The top-level node is mostly a mainframe computer while other nodes in the hierarchy are mini or microcomputers. In this arrangement, the node at each level could be forming a star network with the nodes it serves. In this case, the structure combines star and bus topologies and inherits their advantages and disadvantages. Advantages ▸ The tree topology is useful in cases where a star or bus cannot be implemented individually. It is most-suited in networking multiple departments of a university or corporation, where each unit (star segment) functions separately, and is also connected with the main node (root node). ▸ The advantages of centralization that are achieved in a star topology are inherited by the individual star segments in a tree network. ▸ Each star segment gets a dedicated link from the central bus. Thus, failing of one segment does not affect the rest of the network. ▸ Fault identification is easy. ▸ The network can be expanded by the addition of secondary nodes. Thus, scalability is achieved. Disadvantages ▸ As multiple segments are connected to a central bus, the network depends heavily on the bus. Its failure affects the entire network. ▸ Owing to its size and complexity, maintenance is not easy and costs are high. Also, configuration is difficult in comparison to that in other topologies. ▸ Though it is scalable, the number of nodes that can be added depends on the capacity of the central bus and on the cable type. A hybrid topology combines two or more topologies and is meant to reap their advantages. Obviously, the advantages and disadvantages of a hybrid topology are a combination of the merits and demerits of the topologies used to structure it. Go through types of network topologies for a detailed description of the various network topologies in use today.