How many types of topology are there?
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 | 9 minute(s) read | Published on: Jul 05, 2023 Updated on: Jul 05, 2023 |
What is meant by network topology?
The topology of the network structure determines how all components are connected to each other. There are two types of topology: physical and logical topology.
Types of network topology
Physical topology means the geometric representation of all the nodes of a network. There are also six types of network topology, which are bus topology, ring topology, tree topology, star, mesh topology and hybrid topology.
1) Bus
- Bus topology means that all stations can be connected to each other through a single cable called the backbone cable.
- Direct connection to the backbone cable is usually possible by connecting each node or with a drop cable to the backbone cable.
- If a node wants to send a message through the network, it will need to place a message on the network. Also, all the stations in the network specify the address by receiving the message.
- Bus topology is mainly used in standard 802.3 (Ethernet) and 802.4 networks.
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is usually much easier to configure than other topologies.
- The backbone cable is usually as a "single line", broadcasting through it the message to all stations.
- CSMA (Carrier Sense Multiple Access) is one of the most common access methods for bus topologies.
CSMA: This is used as a media access control to control the data flow to be able to maintain data integrity, in other words, packets should not be lost. It should also be noted that there are usually two alternative ways to deal with problems that occur when two nodes send messages simultaneously.
- CSMA CD:
CSMA CD (collision detection) is used as an access method for collision detection. Also, when the collision is detected, the transmitter will usually stop transmitting data. For this reason, it will be possible to work on "post-collision recovery".
- CSMA CA:
CSMA CA (Collision Avoidance) is used as an access method to avoid collision by checking the busyness of the transmission medium. If busy, the transmitter will wait until the media is idle. This technique can reduce the probability of collision. It also has no function in "crash recovery".
Advantages of bus topology:
- Having a low-cost cable: in the bus topology, nodes will be able to connect directly without passing through the hub to the cable. As a result, the initial installation cost will be reduced.
- Average data rate: Coaxial or twisted pair cables can usually support bus-based networks up to 10 Mbps.
- Familiar technology: Bus topology has a good reputation as a familiar technology, as installation and troubleshooting techniques. Also, hardware parts will be readily available.
- limited failure: usually failure in one node cannot affect other nodes.
Disadvantages of Bus topology:
- Extensive cabling: due to the simplicity of the bus topology, there will be no need for cabling.
- Difficult troubleshooting: In order to determine cable defects, specialized testing equipment is usually necessary. If any error occurs in the cable, usually the communication of all nodes will be disrupted.
- Signal interference: When two nodes send messages at the same time, it is possible for the signals of both nodes to collide with each other.
- Reconfiguration is difficult: adding new devices to the network usually slows down the network.
- Attenuation: Attenuation loss of signal further leads to communication problems. Usually, repeaters will be used for signal reconstruction.
2) Ring
- The ring topology will be the same as the bus topology, except that there is an end-to-end connection.
- The node receiving the message from the previous computer will try to resend it to the next node.
- Data flow will be possible in one direction, in other words it is unidirectional.
- The flow of data in a single loop will be done as an endless loop.
- Usually there will be no end point, in other words, each node is connected to another node and will not have an end point.
◦ Data flows in a ring topology in a clockwise direction.
◦ The most common way to access ring is actually token passing.
◦ Password: One of the ways to access the network is to transfer the password from one node to another.
◦ Token: As a frame, it is always circulating around the network.
Working password
◦ The movement of a token happens across the network and until it reaches its destination, it is transferred from one computer to another.
◦ The sender allows the token to be changed by including the address with the data.
◦ It is done by transferring data from one device to another until the destination address matches. Also, after receiving the password by the destination device, confirmation will be sent to the sender.
◦ Usually in ring, a token is used as a bearer.
Advantages of ring topology:
◦ Network Management: It is possible to remove faulty devices from the network without disabling the network.
◦ Availability of the product: it is usually possible to access many hardware and software tools for network operation and monitoring.
◦ Cost: Usually the cost of twisted pair cabling is affordable, and it is also easy to access.
As a result, the installation cost is very low.
◦ Reliable: Due to the fact that the communication system of a host computer is not dependent on the network, it is usually reliable.
Disadvantages of ring topology:
◦ Difficult troubleshooting: In order to determine cable defects, it usually requires specialized test equipment. Also, if any error occurs in the cable, there will always be a disruption in the communication of all nodes.
◦ Failure: A failure in a station usually involves the failure of the entire network.
◦ Reconfiguration Difficulty: By adding new devices, the network will slow down.
◦ Latency: Latency proportionality is directly related to the number of nodes.
Adding new devices will increase the communication delay.
3) Star
◦ Star is considered as a network arrangement in which each node is usually not connected to a central hub, switch or a central computer.
◦ The central computer is actually considered as a server and peripheral devices connected to the server or as clients.
◦ To connect computers, coaxial cable or RJ-45 cable is used.
◦ Hubs or switches are actually used as connecting devices in a physical star.
◦ Star is considered as the most popular topology in network implementation.
Advantages of star topology
◦ Efficient troubleshooting: Troubleshooting in star topology will be highly efficient when compared to bus topology. Also, in a bus , the manager will need to inspect cable kilometers. In a star topology, there is usually a connection of all stations to a centralized network.
For this reason, the network manager will need to refer to the single station to solve the problem.
◦ Network control: It is possible to implement complex network control features easily in star topology. Also, the changes made in the star are usually considered automatically.
◦ Limited failure: due to the connection of each station with its own cable to the central hub, usually the failure of one cable will not affect the entire network.
◦ Familiar technology: Star topology is considered a familiar technology due to the availability of affordable tools.
◦ Possibility of easy expansion: due to the ability to add new stations to the open ports in the hub, it will be easily expandable.
◦ Economical: Star topology networks are usually economical due to the use of inexpensive coaxial cable.
◦ High data speed: Supports bandwidth of approximately 100 Mbps.
Ethernet 100BaseT is one of the most popular star topology networks.
Disadvantages of star
◦ Central point of failure: If the central hub or switch goes down, all connected nodes will not be able to communicate with each other.
◦ Cable: Cable routing may have significant routing difficulty.
4) Tree
◦ Tree topology combines the features of bus and star topology.
◦ Tree is actually a hierarchical structure connecting all computers.
◦ Usually, the highest node in a tree topology is considered as the root node, and all other nodes are descendants of the root node.
◦ There is usually a path between two nodes for data transfer. Because of this, there is a parent-child hierarchy.
5) Mesh
◦ The mesh technology of the arrangement as a network provides the connection of computers to each other through various additional connections.
◦ It also has multiple paths from one computer to another.
◦ It usually does not have a switch, hub or any central computer acting as a central point of communication.
◦ Internet is known as an example of mesh topology.
◦ Mesh topology is mainly used for WAN implementations where communication failures are a concern.
◦ Mesh topology is usually used for wireless networks.
◦ Mesh topology, it is possible to use the formula:
number of cables = (n*(n-1))/2;where n represents the number of nodes in the network.
Mesh topology is divided into two categories:◦ Fully connected mesh topology
◦ Partially connected mesh topology
◦ Full Mesh topology: In the full mesh topology, it is possible to connect any computer to all the computers in the network.
◦ Partial mesh : In partial mesh topology, it is not possible to connect all computers.
6) Hybrid
◦ The combination of different topologies is actually the same as the combined .
◦ Hybrid has created communication between links and different nodes for data transmission.
◦ If two or more different topologies are combined together, it is known as a hybrid , and if similar topologies are connected to each other, a combined is not created.