What is a Topology?

 What is a Topology?

Topology is an area of Mathematics, which studies how spaces are organized and how they are structured in terms of position. It also studies how spaces are connected. It is divided into algebraic topology, differential topology, and geometric topology

What Is Network Topology?

o   Network topology is the schematic description of the arrangement of the physical and logical elements of a communication network

o   Network topology refers to the manner in which the links and nodes of a network are arranged to relate to each other. Topologies are categorized as either physical network topology, which is the physical signal transmission medium, or logical network topology, which refers to the manner in which data travels through the network between devices, independent of the physical connection of the devices. Logical network topology examples include twisted pair Ethernet, which is categorized as a logical bus topology, and token ring, which is categorized as a logical ring topology.

o   Network topology refers to how various nodes, devices, and connections on your network are physically or logically arranged in relation to each other.

Types of Topology

• F Bus Topology
• F Ring Topology
• F Star Topology
• F Mesh Topology
• F Hybrid Topology

There are two approaches to network topology:

F  Physical

F  Logical

Physical network topology

§  Wires, cables

§  Refers to the physical connections and interconnections between nodes and the network—the wires, cables, and so forth.

§  The physical network topology refers to the actual connections (wires, cables, etc.) of how the network is arranged. Setup, maintenance, and provisioning tasks require insight into the physical network.

Logical network topology

§  Is a little more abstract and strategic, referring to the conceptual understanding of how and why the network is arranged the way it is, and how data moves through it.

§  – The logical network topology is a higher-level idea of how the network is set up; including which nodes connect to each other and in which ways, as well as how data is transmitted through the network.

§   Logical network topology includes any virtual and cloud resources

What Is Bus Topology

o   A bus topology orients all the devices on a network along a single cable running in a single direction from one end of the network to the other—which is why it’s sometimes called a “line topology” or “backbone topology.” Data flow on the network also follows the route of the cable, moving in one direction.

In bus topology there is a main cable and all the devices are connected to this main cable through drop lines. There is a device called tap that connects the drop line to the main cable. Since all the data is transmitted over the main cable, there is a limit of drop lines and the distance a main cable can have.

Advantages of bus topology

Ü  Easy installation, each cable needs to be connected with backbone cable.

Ü  Less cables required than Mesh and star topology

Disadvantages of bus topology

Ü  Difficultly in fault detection.

Ü  Not scalable as there is a limit of how many nodes you can connect with backbone cable.

What Is Ring Topology?

Ring topology is where nodes are arranged in a circle (or ring). The data can travel through the ring network in either one direction or both directions, with each device having exactly two neighbors

Advantages of Ring Topology

P  Easy to install.

P  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

P  A link failure can fail the entire network as the signal will not travel forward due to failure.

What Is Star Topology?

A star topology, the most common network topology, is laid out so every node in the network is directly connected to one central hub via coaxial, twisted-pair, or fiber-optic cable. Acting as a server, this central node manages data transmission—as information sent from any node on the network has to pass through the central one to reach its destination—and functions as a repeater, which helps prevent data loss.

F  In star topology each device in the network is connected to a central device called hub. Unlike Mesh topology, star topology doesn’t allow direct communication between devices, a device must have to communicate through hub. If one device wants to send data to other device, it has to first send the data to hub and then the hub transmit that data to the designated device.

Advantages of Star topology

Q  Less expensive because each device only needs one I/O port and needs to be connected with hub with one link.

Q  Easier to install

Q  Less amount of cables required because each device needs to be connected with the hub only.

Q  Robust, if one link fails, other links will work just fine.

Q  Easy fault detection because the link can be easily identified.

Disadvantages of Star topology

Q  If hub goes down everything goes down, none of the devices can work without hub.

Q  Hub requires more resources and regular maintenance because it is the central system of star topology.

 

What Is Mesh Topology?

 

 

·      A mesh topology is a network setup where each computer and network device is interconnected with one another. This topology setup allows for most transmissions to be distributed even if one of the connections goes down. It is a topology commonly used for wireless networks. Below is a visual example of a simple computer setup on a network using a mesh topology.

·         A mesh topology is an intricate and elaborate structure of point-to-point connections where the nodes are interconnected. Mesh networks can be full or partial mesh. Partial mesh topologies are mostly interconnected, with a few nodes with only two or three connections, while full-mesh topologies are—surprise!—fully interconnected.

·         In mesh topology each device is connected to every other device on the network through a dedicated point-to-point link. When we say dedicated it means that the link only carries data for the two connected devices only. Let’s say we have n devices in the network then each device must be connected with (n-1) devices of the network. Number of links in a mesh topology of n devices would be N (N-1)/2.

There are two types of Mesh topologies –

1.     Fully-connected Mesh Topology

2.     Partially-connected Mesh Topology

1. Full Mesh Topology:

v  All the nodes within the network are connected with every other If there are n number of nodes during a network, each node will have an n-1 number of connections.

v  A full mesh provides an excellent deal of redundancy, but because it is prohibitively expensive to implement, it’s usually reserved for network backbones

 2. Partial Mesh Topology:

v  The partial mesh is more practical as compared to the full mesh.

v  In a partially connected mesh, all the nodes aren’t necessary to be connected with one another during a network. Peripheral networks are connected using partial mesh and work with a full-mesh backbone in tandem.

Advantages of Mesh topology

Ü  No data traffic issues as there is a dedicated link between two devices which means the link is only available for those two devices.

Ü  Mesh topology is reliable and robust as a failure of one link doesn’t affect other links and the communication between other devices on the network.

Ü  Mesh topology is secure because there is a point-to-point link thus unauthorized access is impossible.

Ü  Fault detection is easy.

Ü  Failure during a single device won’t break the network.

Ü  It provides high privacy and security.

Disadvantages of Mesh topology

Ü  Amount of wires required to connect each system is tedious and a headache.

Ü  Since each device needs to be connected with other devices, the number of I/O ports required must be huge.

Ü  Scalability issues because a device cannot be connected with a large number of devices with a dedicated point-to-point link.

 

What Is Hybrid Topology?

 

·         A combination of two or more topologies is known as hybrid topology. For example a combination of star and mesh topology is known as hybrid topology

Advantages of Hybrid topology

@  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.

Scalable as we can further connect other computer networks with the existing networks with different topologies.

Disadvantages of Hybrid topology

@  Fault detection is difficult.

@  Installation is difficult.

@  Design is complex so maintenance is high thus expensive.