TechnologyandScience: Types of Network Topology

Types of Network Topology: Types of Network Topologies are: Bus Topology, Ring Topology, Star Topology, Tree Topology, Mesh Topology & Hybrid Topology with Advantages and Disadvantages

Types of Network Topology: Types of Network Topologies are: Bus Topology Definitions Advantages of Bus Topology Disadvantages of Bus Topology Ring Topology Definitions Working of Token Passing Advantages of Ring Topology Disadvantages of Ring Topology Star Topology Definitions Advantages of Star Topology Disadvantages of Star topology Tree Topology Definitions Advantages of Tree Topology Disadvantages of Tree Topology Mesh Topology Definitions Mesh Topology is divided into 2 categories Advantages of Mesh Topology Disadvantages of Mesh topology Hybrid Topology Definitions Advantages of Hybrid Topology Disadvantages of Hybrid Topology

Types of Network Topology

A network topology refers to the way in which the various elements present in a communication network—such as links and nodes—are arranged. Currently, there are Six primary types of network topologies which are known as: Mesh, Ring, Star, Bus, Tree and Hybrid. To learn more about the different types of computer network topologies, continue reading.

We will Contents following Topics of Types of Network Topologies are:

Bus Topology

Definitions
Advantages of Bus Topology
Disadvantages of Bus Topology

Ring Topology

Definitions
Working of Token Passing
Advantages of Ring Topology
Disadvantages of Ring Topology

Star Topology

Definitions
Advantages of Star Topology
Disadvantages of Star Topology

Tree Topology

Definitions
Advantages of Tree Topology
Disadvantages of Tree Topology

Mesh Topology

Definitions
Mesh Topology is divided into 2 categories
Advantages of Mesh Topology
Disadvantages of Mesh Topology

Hybrid Topology

Definitions
Advantages of Hybrid Topology
Disadvantages of Hybrid Topology

Bus Network Topology

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.

The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable. Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable.

When a node wants to send a message over the network, it puts a message over the network. All the stations available in the network will receive the message whether it has been addressed or not.

The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks.
The configuration of a bus topology is quite simpler as compared to other topologies.
The backbone cable is considered as a “single lane” through which the message is broadcast to all the stations.
The most common access method of the bus topologies is CSMA (Carrier Sense Multiple Access)

In a bus network topology, every device in the network is connected to a single main cable through drop lines. This network topology transmits data in a single direction from one end of the cable to the other. Bus network topologies are cost-effective, easy to understand, and often used in small networks. However, if the main cable fails, the entire network will fail, and fault detection is often difficult.

All the nodes connect directly to a main cable which acts as a backbone for the network. At the end of the cable is a “terminator”, which prevents signals from bouncing off the end of the cable.
Usually a 10 base 5 network where computers connect with “T” connectors
All signals are sent as a broadcast. It travels down back bone and goes to each end point
One of the computers in the network typically acts as the computer server.

Advantages of Bus Topology

Bus topologies are a good, cost-effective choice for smaller networks because the layout is simple, allowing all devices to be connected via a single coaxial or RJ45 cable. If needed, more nodes can be easily added to the network by joining additional cables.

Low-cost cable: In bus topology, nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low.
Moderate data speeds: Coaxial or twisted pair cables are mainly used in bus-based networks that support upto 10 Mbps.
Familiar technology: Bus topology is a familiar technology as the installation and troubleshooting techniques are well known, and hardware components are easily available.
Limited failure: A failure in one node will not have any effect on other nodes.
It is easiest to set up and connect to computer or peripheral device.
The cable requirements are relatively small, resulting in lower cost.

Dis-Advantages of Bus Topology

However, because bus topologies use a single cable to transmit data, they’re somewhat vulnerable. If the cable experiences a failure, the whole network goes down, which can be time-consuming and expensive to restore, which can be less of an issue with smaller networks.

Bus topologies are best suited for small networks because there’s only so much bandwidth, and every additional node will slow transmission speeds. Furthermore, data is “half-duplex,” which means it can’t be sent in two opposite directions at the same time, so this layout is not the ideal choice for networks with huge amounts of traffic.

Extensive cabling: A bus topology is quite simpler, but still it requires a lot of cabling.
Difficult troubleshooting: It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
Signal interference: If two nodes send the messages simultaneously, then the signals of both the nodes collide with each other.
Reconfiguration difficult: Adding new devices to the network would slow down the network.
Attenuation: Attenuation is a loss of signal leads to communication issues. Repeaters are used to regenerate the signal.
It is of limited length.
All nodes could see all packets on the network.
If one node goes down, the network goes down as it is if you broke the circuit.

Ring Network Topology

A Ring Topology includes devices that are each connected to two neighboring devices. Because the last device is connected to the first, the topology forms a circle, or ring. To send data to other devices in the network, the data must be sent in one direction. Each device has a repeater so that it can forward the data until it reaches the intended device. A ring topology is typically easy to install, scalable, and redundant.

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.

Ring topology is like a bus topology, but with connected ends.
The node that receives the message from the previous computer will retransmit to the next node.
The data flows in one direction, i.e., it is unidirectional.
The data flows in a single loop continuously known as an endless loop.
It has no terminated ends, i.e., each node is connected to other node and having no termination point.
The data in a ring topology flow in a clockwise direction.
The most common access method of the ring topology is token passing.

Token Passing: It is a network access method in which token is passed from one node to another node.

Token: It is a frame that circulates around the network.

Working of Token Passing:

A token moves around the network, and it is passed from computer to computer until it reaches the destination.
The sender modifies the token by putting the address along with the data.
The data is passed from one device to another device until the destination address matches. Once the token received by the destination device, then it sends the acknowledgment to the sender.
In a ring topology, a token is used as a carrier.

Advantages of Ring Topology

Since each device is only connected to the ones on either side, when data is transmitted, the packets also travel along the circle, moving through each of the intermediate nodes until they arrive at their destination. If a large network is arranged in a ring topology, repeaters can be used to ensure packets arrive correctly and without data loss.

Only one station on the network is permitted to send data at a time, which greatly reduces the risk of packet collisions, making ring topologies efficient at transmitting data without errors. By and large, ring topologies are cost-effective and inexpensive to install, and the intricate point-to-point connectivity of the nodes makes it relatively easy to identify issues or misconfigurations on the network.

Network Management: Faulty devices can be removed from the network without bringing the network down.
Product availability: Many hardware and software tools for network operation and monitoring are available.
Cost: Twisted pair cabling is inexpensive and easily available. Therefore, the installation cost is very low.
Reliable: It is a more reliable network because the communication system is not dependent on the single host computer

Disadvantages of Ring Topology

Difficult troubleshooting: It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.

Failure: The breakdown in one station leads to the failure of the overall network.
Reconfiguration difficult: Adding new devices to the network would slow down the network.
Delay: Communication delay is directly proportional to the number of nodes. Adding new devices increases the communication delay.

Even though it’s popular, a ring topology is still vulnerable to failure without proper network management. Since the flow of data transmission moves unidirectionally between nodes along each ring, if one node goes down, it can take the entire network with it. That’s why it’s imperative for each of the nodes to be monitored and kept in good health. Nevertheless, even if you’re vigilant and attentive to node performance, your network can still be taken down by a transmission line failure.

The question of scalability should also be taken into consideration. In a ring topology, all the devices on the network share bandwidth, so the addition of more devices can contribute to overall communication delays. Network administrators need to be mindful of the devices added to the topology to avoid overburdening the network’s resources and capacity. Additionally, the entire network must be taken offline to reconfigure, add, or remove nodes. And while that’s not the end of the world, scheduling downtime for the network can be inconvenient and costly.

Star Network Topology

A star topology consists of devices that are all connected to a single hub through dedicated connections. As such, if there are n devices in a network, and the number of physical channels to connect them is also n.

Due to their simplicity, star network topologies are relatively easy to set up. However, because the devices are only connected to the hub and not each other, direct communication between devices is not possible. Instead, data must first be sent to the hub, which will then transmit it to the desired device. Thus, if the hub goes down, the entire network will fail to operate.

Each computer connects to a central hub (could be a switch as well) using point-to-point connections. A hub would broadcast the data across the entire network, where as a switch would map MAC addresses.

Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer.
The central computer is known as a server, and the peripheral devices attached to the server are known as clients.
Coaxial cable or RJ-45 cables are used to connect the computers.
Hubs or Switches are mainly used as connection devices in a physical star topology.
Star topology is the most popular topology in network implementation.

Advantages of Star Topology

Efficient troubleshooting: Troubleshooting is quite efficient in a star topology as compared to bus topology. In a bus topology, the manager has to inspect the kilometers of cable. In a star topology, all the stations are connected to the centralized network. Therefore, the network administrator has to go to the single station to troubleshoot the problem.
Network control: Complex network control features can be easily implemented in the star topology. Any changes made in the star topology are automatically accommodated.
Limited failure: As each station is connected to the central hub with its own cable, therefore failure in one cable will not affect the entire network.
Familiar technology: Star topology is a familiar technology as its tools are cost-effective.
Easily expandable: It is easily expandable as new stations can be added to the open ports on the hub.
Cost effective: Star topology networks are cost-effective as it uses inexpensive coaxial cable.
High data speeds: It supports a bandwidth of approx 100Mbps. Ethernet 100BaseT is one of the most popular Star topology networks.

Good traffic handling if we use a switch, which will reduce the collision domain.

Addition or deletion of nodes can be done easily, so its good for small home/office settings.

Any failure at a single node does not effect the whole network.

It is easy to diagnose a star network. Simply diagnosing the HUB will show up which node is bad.

We can use several cable type in the same network with a hub that can support multiple cable types.

Disadvantages of Star Topology

A Central point of failure: If the central hub or switch goes down, then all the connected nodes will not be able to communicate with each other.
Cable: Sometimes cable routing becomes difficult when a significant amount of routing is required.
Single point of failure at the central hub.
Using a dumb hub could be a security risk.
The Extended Star Topology refers to a network topology that combines an Ethernet network with several LANs extending beyond a single level.

Tree Network Topology

The tree topology structure gets its name from how the central node functions as a sort of trunk for the network, with nodes extending outward in a branch-like fashion. However, where each node in a star topology is directly connected to the central hub, a tree topology has a parent-child hierarchy to how the nodes are connected.

Those connected to the central hub are connected linearly to other nodes, so two connected nodes only share one mutual connection. Because the tree topology structure is both extremely flexible and scalable, it’s often used for wide area networks to support many spread-out devices.

Tree topology combines the characteristics of bus topology and star topology.
A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion.
The top-most node in tree topology is known as a root node, and all other nodes are the descendants of the root node.
There is only one path exists between two nodes for the data transmission. Thus, it forms a parent-child hierarchy.

Advantages of Tree Topology

Combining elements of the star and bus topologies allows for the easy addition of nodes and network expansion. Troubleshooting errors on the network is also a straightforward process, as each of the branches can be individually assessed for performance issues.

Support for broadband transmission: Tree topology is mainly used to provide broadband transmission, i.e., signals are sent over long distances without being attenuated.
Easily expandable: We can add the new device to the existing network. Therefore, we can say that tree topology is easily expandable.
Easily manageable: In tree topology, the whole network is divided into segments known as star networks which can be easily managed and maintained.
Error detection: Error detection and error correction are very easy in a tree topology.
Limited failure: The breakdown in one station does not affect the entire network.
Point-to-point wiring: It has point-to-point wiring for individual segments.

Disadvantages of Tree Topology

As with the star topology, the entire network depends on the health of the root node in a tree topology structure. Should the central hub fail, the various node branches will become disconnected, though connectivity within, but not between branch systems will remain.

Because of the hierarchical complexity and linear structure of the network layout, adding more nodes to a tree topology can quickly make proper management an unwieldy, not to mention costly, experience. Tree topologies are expensive because of the sheer amount of cabling required to connect each device to the next within the hierarchical layout.

Difficult troubleshooting: If any fault occurs in the node, then it becomes difficult to troubleshoot the problem.
High cost: Devices required for broadband transmission are very costly.
Failure: A tree topology mainly relies on main bus cable and failure in main bus cable will damage the overall network.
Reconfiguration difficult: If new devices are added, then it becomes difficult to reconfigure.

Mesh Network Topology

Mesh technology is an arrangement of the network in which computers are interconnected with each other through various redundant connections.

There are multiple paths from one computer to another computer.
Ring Topology
It does not contain the switch, hub or any central computer which acts as a central point of communication.
The Internet is an example of the mesh topology.
Mesh topology is mainly used for WAN implementations where communication failures are a critical concern.
Mesh topology is mainly used for wireless networks.
Mesh topology can be formed by using the formula: Number of cables = (n*(n-1))/2;
Where n is the number of nodes that represents the network.

Mesh topology is divided into two categories

Fully connected mesh topology.
Partially connected mesh topology.

Full Mesh Topology:

In a full mesh topology, each computer is connected to all the computers available in the network.

Partial Mesh Topology:

In a partial mesh topology, not all but certain computers are connected to those computers with which they communicate frequently.

Advantages of Mesh Topology

Multiple paths are can be used for transmitting a message.
Due to the presence of direct, dedicated links, mesh topologies do not have any traffic problems.
Mesh topologies are reliable and stable, and the complex degree of interconnectivity between nodes makes the network resistant to failure. For instance, no single device going down can bring the network offline.
Fast Communication: Communication is very fast between the nodes.
Easier Reconfiguration: Adding new devices would not disrupt the communication between other devices.

Disadvantages of Mesh Topology

Mesh topologies are incredibly labor-intensive. Each interconnection between nodes requires a cable and configuration once deployed, so it can also be time-consuming to set up. As with other topology structures, the cost of cabling adds up fast, and to say mesh networks require a lot of cabling is an understatement.

Cost: A mesh topology contains a large number of connected devices such as a router and more transmission media than other topologies.
Management: Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.
Efficiency: In this topology, redundant connections are high that reduces the efficiency of the network.
Difficult maintenance costs. You can’t defer maintenance just because you have a mesh network.

Hybrid Network Topology

A hybrid topology is a combination of two or more different types of topologies. For example, a hybrid topology may consist of a ring topology that is used in one department of a company and a mesh topology that is used in another to form one complex topology. By combining two or more topologies together, a network is able to take advantage of the benefits of multiple topologies. However, it is important to remember that the network will also inherit the disadvantage of its combined topology types as well.

Hybrid topologies combine two or more different topology structures—the tree topology is a good example, integrating the bus and star layouts. Hybrid structures are most commonly found in larger companies where individual departments have personalized network topologies adapted to suit their needs and network usage.

The combination of various different topologies is known as Hybrid topology.
A Hybrid topology is a connection between different links and nodes to transfer the data.
When two or more different topologies are combined together is termed as Hybrid topology and if similar topologies are connected with each other will not result in Hybrid topology. For example, if there exist a ring topology in one branch of ICICI bank and bus topology in another branch of ICICI bank, connecting these two topologies will result in Hybrid topology.

Advantages of Hybrid Topology

The main advantage of hybrid structures is the degree of flexibility they provide, as there are few limitations on the network structure itself that a hybrid setup can’t accommodate.

Reliable: If a fault occurs in any part of the network will not affect the functioning of the rest of the network.
Scalable: Size of the network can be easily expanded by adding new devices without affecting the functionality of the existing network.
Flexible: This topology is very flexible as it can be designed according to the requirements of the organization.
Effective: Hybrid topology is very effective as it can be designed in such a way that the strength of the network is maximized and weakness of the network is minimized.

Disadvantages of Hybrid Topology

However, each type of network topology comes with its own disadvantages, and as a network grows in complexity, so too does the experience and know-how required on the part of the admins to keep everything functioning optimally. There’s also the monetary cost to consider when creating a hybrid network topology.

Complex design: The major drawback of the Hybrid topology is the design of the Hybrid network. It is very difficult to design the architecture of the Hybrid network.
Costly Hub: The Hubs used in the Hybrid topology are very expensive as these hubs are different from usual Hubs used in other topologies.
Costly infrastructure: The infrastructure cost is very high as a hybrid network requires a lot of cabling, network devices etc.

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