Classification of network Based on Topology
What is Topology ?
Geometric representation of how the computers are connected to each other is known as topology. There are five types of topology – Bus, Star, Ring, Mesh and Hybrid.
BUS
As it uses less cable, it is simple to build and less expensive compared to the other network topologies. Adding new nodes to the network is easier and can be achieved by simply joining additional cables with connectors.
Advantages of bus topology
1. Easy installation, each cable needs to be connected with backbone cable.
2. Less cables required than Mesh and star topology
Disadvantages of bus topology
1. Difficultly in fault detection.
2. Not scalable as there is a limit of how many nodes you can connect with backbone cable.
Star
A star topology is the one in which each peripheral node is connected to a central hub or switch. It is probably the most commonly used network topology for LAN because it is considered the easiest topology to design and implement. The central hub functions as the server for the peripheral nodes or clients. All the network traffic passes through the central hub and this is the only requirement for the topology to be classified as a star topology; the network doesn’t have to resemble a star in the physical arrangement.
Advantages of Star topology
1. Less expensive because each device only need one I/O port and needs to be connected with hub with one link. 2. Easier to install 3. Less amount of cables required because each device needs to be connected with the hub only. 4. Robust, if one link fails, other links will work just fine.
Disadvantages of Star topology
1. If hub goes down everything goes down, none of the devices can work without hub. 2. Hub requires more resources and regular maintenance because it is the central system of star topology.
Ring
As we mentioned earlier, the ring topology is similar to a daisy chain topology but with the loop closed so that the nodes are arranged in a ring or circle. Each node has exactly two peers and the data travels in one direction passing through each intermediate node on the ring until it reaches the destination node. Data can be made to pass in both directions by adding a second connection between the network nodes, creating a dual ring topology.
Advantages of Ring Topology
1. Easy to install.
2. Managing is easier as to add or remove a device from the topology only two links are required to be changed.
Disadvantages of Ring Topology
1. A link failure can fail the entire network as the signal will not travel forward due to failure.
2. Data traffic issues, since all the data is circulating in a ring.
Mesh
A mesh topology is one in which the nodes connect directly and dynamically to many other nodes. It consists of an elaborate structure of point-to-point interconnections among the nodes. You can have a partial mesh topology, where some nodes have two or more connections, or a full mesh topology, where all nodes are fully connected to every other node.
Advantages of Mesh topology
1. No data traffic issues as there is a dedicated link between two devices which means the link is only available for those two devices.
2. Mesh topology is reliable and robust as failure of one link doesn’t affect other links and the communication between other devices on the network.
3. Mesh topology is secure because there is a point to point link thus unauthorized access is not possible.
4. Fault detection is easy.
Disadvantages of Mesh topology
1. Amount of wires required to connected each system is tedious and headache.
2. Since each device needs to be connected with other devices, number of I/O ports required must be huge.
3. Scalability issues because a device cannot be connected with large number of devices with a dedicated point to point link.
Hybrid
A hybrid topology is one in which two or more distinct typologies are combined to build a network in such a way that it doesn’t exhibit any of the standard typologies. Hybrid typologies are commonly found in larger organizations where individual departments can have personalized network typologies based on their needs and network requirements.
Advantages of Hybrid topology
1. We can choose the topology based on the requirement for example, scalability is our concern then we can use star topology instead of bus technology.
2. Scalable as we can further connect other computer networks with the existing networks with different typologies.
Disadvantages of Hybrid topology
1. Fault detection is difficult.
2. Installation is difficult.
3. Design is complex so maintenance is high thus expensive.
