In Computer Network a Network topology is the arrangement of computer system and network devices which are connected to each other. It also defines the logical flow of information in the network. Depending on the need and requirements of the newtwork different types of the network topologies are used. Some of the most used network topologies are as follow:
Point to Point network topology contains exactly two hosts. Information is being transfered between these two hosts. The receiving end of one host is connected to sending end of the other and vice-versa.
In bus topology all devices are connected to a single communication channel or cable. The information between diffferent nodes are transfered using this common cabel. It is one of most simple form of network topology. In Bus topology failure of a single device does not affect the other devices. But failure off the common cable stop communication between all the devices.
At the ends of each the communication cable there is a terminator. The data is sent in only one direction and as soon as it reaches the extream end, the terminator removes the data from the line.
Advantages of Bus Topology:
Number of cables required to join N devices is N+1 as there is 1 common cable required for all the devices The cost of the cable is less as compared to other topologies, but it is used to build small networks.
Disadvantages of Bus Topology:
If the common cable fails, then the whole system will crash down. Security is low.
In Ring Topology one device is exactly connected to two adjancet devices which forms a ring thus called Ring Topology. When one host tries to communicate or send message to a host which is not adjacent to it, the data travels through all intermediate hosts. To connect one more host in the existing structure, the administrator may need only one more extra cable.
Advantages of Ring Topology:
Easy to install. Less cable are reqired.
Disadvantages of Ring Topology:
If a node fails, the whole network will fail. Difficult to reconfigure(we have to break the ring).
Star Topology is a topology in which all the devices are connected to a central device called hub. Hub has a point to point dedicated communication link(which can only be used by the dedicated connection) with each node.
Advantages of Star Topology:
Easy to install. Less cable are reqired.
Disadvantages of Star Topology:
If a node fails, the whole network will fail. Difficult to reconfigure(we have to break the ring).
In Mesh Topology all the devices are connected to each other with a dedicated link, So in mesh topology communication take place directly between the two nodes in the network. There are two types of Mesh topology: Full Mesh and Partially Mesh
Types of Mesh Topology:
Full Mesh: In full mesh all the nodes have a point to point connection to each and every node of the network. It provides the most reliable network structure among all network topologies. Partially Mesh: Not all hosts have point-to-point connection to every other host. This topology exists where we need to provide reliability to some hosts out of all.
Advantages of Mesh Topology:
It is very fast. Provides security and privacy. The fault is diagnosed easily.
Disadvantages of Mesh Topology:
Installation and Maintainance cost is high. Installation is difficult. Not suitable for large networks as in large network it will require more wires which results in higher cost.
It is a combination of bus and star topology because all the nodes are connected to main bus cable. This is the most common form of network topology in use presently. Tree topology is also known as Hierarchical Topology.
In a tree topology, the whole network is divided into multiple layers of the network mainly in Access Layers, Middle Layer and Core Layer. The lower most layer is called access layer where nodes are concted. The middle layer works as mediator between upper and lower layer. The highest layer of the network is called Core Layer. And is called the root of the network.
Advantages of Tree Topology:
Large distance network coverage. Data privacy and security as hierarchical networks are isolated.
Disadvantages of Tree Topology:
Cost is high because of required cables and hardware Difficult installation If the main bus fails the whole network will fail.
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