## What Is Network Topology?

Network topology refers to how various nodes, devices, and connections on your network are physically or logically arranged in relation to each other. Think of your network as a city, and the topology as the road map. Just as there are many ways to arrange and maintain a city—such as making sure the avenues and boulevards can facilitate passage between the parts of town getting the most traffic—there are several ways to arrange a network. Each has advantages and disadvantages and depending on the needs of your company, certain arrangements can give you a greater degree of connectivity and security.

Network topology is also the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

There are two approaches to network topology: physical and logical. Physical network topology, as the name suggests, refers to the physical connections and interconnections between nodes and the network—the wires, cables, and so forth. 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.

What are the types of network topology

In computer networks, these are the types of  network topologies, they are: Physical Topology: A physical topology describes the way in which the computers or nodes are connected with each other in a computer network. … Logical Topology: A logical topology describes the way, data flow from one computer to another

Other types of topologies in computer networks:

• Mesh Topology.
• Star Topology.
• Bus Topology.
• Ring Topology.
• Hybrid Topology

There are many types of physical topology. Some popular types are discussed as follows:

## 1. Peer–to–Peer Arrangement

Sometimes this is called as a point-to-point link. Each point–to–point link contains one transmitter and one receiver. Each station receives data exactly from one transmitter and each transmitter transmits data to exactly one receiver. Receiving and transmission process can be done over a single wire or can use separate wires for better performance.

## 2. Bus Topology

Bus topology is also called point–to–multi–point arrangement. In a bus topology, all nodes or devices are linked with one transmitter or server computer via a single cable (mostly coaxial cable) called backbone. All nodes are connected to the bus cable by drop lines. A drop line is a connection running between the nodes and the main cable.

## 3. Star Topology

In a star topology, each node has a dedicated point–to–point connection with a central server, normally called a hub. The nodes are not directly connected to each other. Hence, direct data flow is not allowed in between the nodes. The central server or hub acts as a data exchanger as one node sends data exactly to hub and hub transmits this data to another node.

## 4. Tree Topology

Tree topology is a combination of one or more star topology arrangements. All the sub-central hubs are connected to a main central hub to form a tree topology. A cable TV network is a good example of this type of topology.

## 5. Ring Topology

In a ring topology, each node has a dedicated point–to–point line configuration with the two nodes on either side of it. A signal is passed along the ring in one direction, from node to node, until it reaches its receiver. Each node in the ring is integrated as a repeater. When a node receives a signal intended from another node, its repeater regenerates the bits and passes them along.

## 6. Mesh Topology

In a mesh topology, each node has a dedicated point–to–point connection with the rest of the nodes in the network. Dedicated connection means data can only be flown between two nodes.

## 7. Hybrid Topology

This topology is a common arrangement of one or more topologies described above. It means one or more above described topologies connect with each other to form a hybrid network arrangement.

### 1: Point-to-Point Topology:

In point-to-point Topology, connection provides a common link between two devices. The entire bandwidth of the link is reserved for transmission between those two devices. This simplest point-to-point connections use an actual length of wire or cable to connect the two ends.

When you change TV channels by infrared remote control, you are establishing a point-to-point (P2P) connection between the remote control and the TV’s control system. Two Computers communication through the modems

Advantages: This is faster and more reliable network topology than other types of topologies since there is a direct connection.

Disadvantage: This topology can only be used for small areas where computers (nodes) are closely located.

### 2: Bus Topology:

A bus topology consists of a single cable with the terminator at each end. All available devices are connected to the single cable. One single cable acts as the backbone for the whole network.

In a bus topology, one of the computers acts as the server and transmits the data from one end to the other in a single direction. When the data reaches to the extreme end, the terminator removes the data from the line.

Characteristics of Bus Topology:

• Flexible
• Expandable
• Moderate Reliability
• Moderate performance

1. Easy to connect or remove nodes in a network without affecting any other node.
2. In case of any node failure, the will be no effect on other nodes or network.
3. Cable cost is less as compared to other network topologies (mesh and star).
4. It is easy to understand topology.
5. Easy to expand by joining two cable

1. In case of any node failure it is difficult to find faults in a network.
2. If the backbone cable damages the entire network will fail.
3. If network traffic increases or nodes increases, the performance of network decreases.
4. It is slower because one computer transmit at a time.
5. The length of cable is limited

Bus topology was the one of the first topologies used in the design of early LANs (local area networks).

### 3: Ring Topology:

In Ring Topology, each computer or node is connected with its neighboring computer forming the shape of ring hence it is known as Ring Topology.

In ring topology the data travels in a circular fashion from one computer to another (clockwise or counter clockwise). In case of any failure in a cable or device break the circular loop and can take down the entire network.

1. Data flow is in circular direction which reduces the chance of packet collision.
2. A network server is not needed to control the flow of data.
3. The maintenance of ring network is much easier compared to the bus topology.
4. It provides good communication over a long distance.
5. It can handle high volume of nodes in a network.
6. It is less costly compared to the mesh, tree, and hybrid topology.
7. Troubleshooting is much easier because cable faults can be located easily in ring topology.

1. A single break in the cable can cause a disturbance in the entire network
2. Addition and removal of any node in a network is difficult and can cause issue in network activity.
3. It is much slower than Ethernet network under normal load conditions.

Ring topology was most common, when IBM introduced its first local-area network Token Ring. Today, the need for high speed Local area networks has made this topology less popular.

### 4: Star Topology:

In Start Topology, all the computers (nodes) go to the central location having a device called as hub. All the devices on the network are connected with a hub device through a link. Each device requires a single wire for the connection to the hub.

In star Topology, there exists a point-to-point connection between a node and hub. The hub takes a signal from any node and passes it along to all the other nodes in the network. The hub controls and manages entire function of the network.

Characteristics of Star Topology:

• High Speed
• Very Flexible
• High Reliability
• High Maintainability

1. Easy to manage because each node require separate cable.
2. Easy to locate problems because cable failure only affect a single user.
3. Easy to expand without disturbing to the network
4. Due to Hub device network management is much easier.
5. Fault identification is easy, also it is easy to remove nodes
6. Star topology provides very High speeds of data transfer.

1. If the hub device goes down, the entire network will be dead.
2. Star topology requires more wires compared to the ring and bus topology.
3. Whole performance of the network depends on the hub.

The star topology is most widely used topology in today’s local-area networks (LANs) due to its numerous advantages.

### 5: Mesh Topology:

In Mesh Topology, all the computers are connected to each other in a network. It is very difficult to establish the connections of the mesh topology. In a Mesh topology every computer has a point-to-point connection to the other computer.

In order to connect n nodes, mesh topology require n(n-1)/2 communication links. Communication link can be twisted pair, co-axial cable or optical fiber

Characteristics of Mesh Topology:

• Fully connected
• Robust
• Not flexible
• Poor expand-ability

1. No traffic problem as there are dedicated links for each computer.
2. It has multiple links, so if one route is blocked then other can be accessed for data communication.
3. It provides high privacy and security.
4. Due to point-to-point links, fault identification is easy

1. It requires high number of cabling and I/o ports for the communication.
2. Installation is very complex in mesh topology, as each node is connected to every node.
3. It is costly compared to the other network topologies.

Due to these reasons a mesh topology is usually implemented in a limited manner.

### 6: Tree Topology:

In Tree Topology, all the computer are connected to the central hub, in the computer networking, tree topology is known as combination of a star network topology and a bus topology. In tree topology, all the computers are connected like the branches of a tree. The main advantages of this topology are flexibility and scalability.

1. It is combination of bus and star topology
2. It provides high scalability, as leaf nodes can add more nodes in the hierarchical chain.
3. In case of any node failure, other hierarchical networks are not affected.
4. It provides easy maintenance and fault identification.
5. Supported by several hardware and software vendors.
6. Point-to-point wiring for individual segments.

1. Large cabling is required as compared to star and bus topology.
2. On the failure of hub, entire network fails.
3. Tree topology is very difficult to configure than other topologies.

### 7: Hybrid Topology:

Hybrid topology is the combination of more than two topologies.  In a computer networking, a network structure that contains more than two topologies is known as hybrid topology. It inherits the advantages and disadvantages of included topologies.

Hybrid topology include a mix of bus topology, mesh topology, ring topology, star topology, and tree topology. The combination of topology depends on the requirement of organization.

1. Hybrid topology Combines the benefits of different types of topologies
2. Can be modified as per requirement
3. It is extremely flexible.
4. It is very reliable.
5. It is easily scalable