In computer networking, physical structures refer to the tangible components and infrastructure that make up a network. These physical elements provide the foundation for data transmission and communication between devices within a network. They include:
- Cables: Cables are used to establish physical connections between devices in a network. Common types of cables used in networking include Ethernet cables (such as twisted-pair copper cables or fiber optic cables), coaxial cables, and serial cables. These cables carry the electrical or optical signals that transmit data between devices.
- Network Interface Cards (NICs): Network Interface Cards, also known as network adapters, are hardware components installed in computers or devices to enable them to connect to a network. NICs provide the physical interface for connecting devices to the network medium, such as an Ethernet port or a wireless radio antenna.
- Hubs, Switches, and Routers: These networking devices facilitate the connectivity and data transfer between multiple devices in a network. Hubs are the simplest form of connectivity devices that broadcast incoming data to all devices connected to them. Switches, on the other hand, are more intelligent devices that forward data packets only to the intended destination device. Routers are responsible for directing data packets between different networks, making them crucial for interconnecting networks.
- Network Servers: Network servers are powerful computers or devices that provide resources and services to other devices on the network. These servers can include file servers, web servers, email servers, database servers, and more. They store and manage data, respond to requests from client devices, and facilitate network-based services.
- Network Cabinets/Racks: These physical structures provide a housing and organization for networking equipment, including switches, routers, servers, and other devices. Network cabinets/racks often feature cable management systems and cooling mechanisms to maintain the integrity and functionality of the network infrastructure.
- Physical Locations and Data Centers: Physical structures also encompass the physical locations where network equipment and servers are housed. This includes data centers, telecommunication rooms, wiring closets, and server rooms. These facilities provide secure and controlled environments for housing networking infrastructure, ensuring reliable and efficient network operations.
Understanding the physical structures of a network is essential for designing, implementing, and maintaining a robust and efficient network infrastructure. These components lay the groundwork for reliable data transmission, connectivity, and communication between devices within a network.
Types of Connections
Two or more devices are connected to each other in a network via links. There are two types of connections possible –
Point-to-Point:
In this type of connection a dedicated link is made between only two devices and no external device can interfere between them. This means the capacity of the link is restricted to those two devices only. Point-to-point connection mostly uses a cable, but it can also be established using infrared, or other satellite links also.
For example, the link between the infrared remote control and television is an example of point-to-point communication.
Multi-point :
In this type of connection, the link is shared between multiple devices. The capacity of the communication is not restricted to the two devices which was seen in the case of point-to-point. It is of two types – spatial and time shared. If many devices can share the link simultaneously, it is known as spatial. And in another case, if devices share the link one by one in a time-shared manner, then it is known as time shared connection.
Physical Topology
Physical Topology is the term used to describe the way in which a network is maintained.
The geometrical representation of a collection of two or more devices along with their links refers to the network topology. Basically, there are four different types of topologies. These are – Mesh, Star, Bus, and Ring.
Mesh
This is a kind of network in which every node is connected to every other node.
This can be of two types – full mesh topology and Partially connected mesh topology.
Full mesh topology
In the full mesh topology, every node is connected to every other node. In this, the number of connections in the network can be calculated by using the formula, n*(n-1)/2. Where, n is the number of computers.
Partially connected mesh topology
In the case of partially connected, at least two of the computers have connections to every other computer in the network. In this case, if one of the computers in the network fails, the rest of the network still works fine.
Advantages of Mesh Topology –
- Can handle a high amount of traffic
- If one of the computers in the network fails, the whole network does not get affected.
- If a new node/computer is added to the network, it does not disrupts the transmission between other devices.
Disadvantages of Mesh Topology –
- The cost to implement is high
- Maintenance cost is high
Read more about – Mesh interconnection network
Star Topology
In star topology, a central device such as a hub, or switch is present. This is the central device which acts as a server and the other devices acts as the clients to it. Each of the clients are connected to the server. Depending upon the type of network card used, the clients are connected to the hub/switch via the coaxial cable of RJ-45 cable.
Advantages of Star Topology –
- Centralized management of the network
- If one computer fails, the other remain unaffected
- Easy to add other devices
- Commonly used in LANs
Disadvantages of Star Topology –
- Higher implementation cost when hub or router is used as a central device.
- The performance of the network depends upon the central device.
- If the central device fails, the whole network is disrupted.
Bus Topology
Bus network topology is a type of computer network in which all devices are connected to a common communication line, also known as the “bus.” In this topology, data is transmitted from one end of the bus to the other and all devices receive the same signal.
A bus network typically consists of a single cable that connects all devices on the network, including computers, printers, and servers. Each device on the network has a unique address, which allows it to communicate with other devices on the network.
Advantages of Bus Topology
One advantage of a bus network is its simplicity and low cost, as only one cable is required. However, if the cable fails, the entire network can be disrupted. Additionally, as all devices on the network receive the same signal, there may be data collisions and performance issues if multiple devices try to transmit data at the same time.
Disadvantages of Bus Topology
Bus topology, while having its advantages, also comes with some disadvantages. Here are a few of the disadvantages of bus topology:
- Limited Scalability: Bus topology is not easily scalable. As more devices are added to the network, the overall performance can degrade. This is because all devices on the network share the same communication channel, and as more devices are connected, the available bandwidth gets divided among them, resulting in slower data transfer rates.
- Single Point of Failure: A bus network is highly dependent on the main communication line, known as the bus. If the bus experiences a failure or gets damaged, the entire network can be affected. When the main bus fails, all devices connected to it lose connectivity, disrupting the entire network until the issue is resolved.
- Difficult Fault Identification and Troubleshooting: Identifying faults or failures in a bus topology can be challenging. If a device malfunctions or there is a break in the communication line, it can be difficult to pinpoint the exact location of the problem. This can lead to increased troubleshooting time and effort, resulting in longer network downtime.
- Limited Cable Length and Number of Devices: Bus topology has restrictions on the cable length and the number of devices that can be connected. The length of the bus cable is limited, and if the network needs to cover a large area, additional repeaters or hubs may be required to extend the reach. Moreover, there is a limit to the number of devices that can be connected to the bus before experiencing performance degradation.
- Lack of Privacy and Security: In a bus topology, all devices share the same communication medium. This lack of privacy can pose security risks, as any device connected to the network can potentially intercept or access data transmitted over the bus. Additional security measures, such as encryption and access controls, are required to mitigate these risks.
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Limited Bandwidth: Bus topology shares the available bandwidth among all connected devices. As more devices communicate simultaneously, the available bandwidth decreases, resulting in slower data transfer rates. This can be a significant disadvantage in networks where high data transfer speeds are required.
Bus network topology was popular in the past, but is now less commonly used in favor of other network topologies such as star and mesh.
Ring Topology
Ring network topology is a type of computer network in which all devices are connected in a closed-loop configuration. In this topology, data is transmitted from one device to the next in a sequential manner until it reaches its destination.
A ring network typically consists of a cable or a series of cables that form a closed loop. Each device on the network is connected to the cable and has a unique address, which allows it to communicate with other devices on the network.
Advantages of a ring network
One of the advantages of a ring network is its fault tolerance. If one device on the network fails, data can be rerouted through other devices on the network, allowing the network to continue to function. Additionally, as data flows in only one direction in a ring network, there are no data collisions that can occur as in a bus network.
Disadvantages of a ring network
However, a disadvantage of a ring network is its limited scalability. The addition of new devices to the network can disrupt the entire network and require significant reconfiguration. Additionally, if the cable connecting the devices fails, the entire network can be disrupted, and troubleshooting can be difficult.
Types of Ring Network Topology
There are two types of ring network topology: the single-ring topology and the dual-ring topology.
Single Ring Topology:
In a single-ring topology, all devices are connected to a single ring, and data flows in only one direction.
Dual Ring Topology
In a dual-ring topology, there are two rings, one for data transmission and one for backup. If the primary ring fails, data can be rerouted through the backup ring to maintain network connectivity.
Key protocols used in ring network topology
One of the key protocols used in ring network topology is the Token Ring protocol, which was developed by IBM. In this protocol, data is transmitted in a circular pattern, with each device on the network taking turns transmitting data. A token is used to control access to the network, with devices only able to transmit data when they have possession of the token.
In addition to the Token Ring protocol, other protocols can also be used in ring network topology, such as the Fiber Distributed Data Interface (FDDI) protocol. FDDI is a high-speed networking protocol that can support data transfer rates of up to 100 Mbps.
Ring network topology was popular in the past, but it is now less commonly used in favor of other network topologies such as star and mesh. However, it is still used in some specialized applications where high availability and fault tolerance are critical, such as in the telecommunications industry.
Hybrid Network Topologies
A hybrid network topology is a combination of two or more different types of network topologies, such as bus, ring, star, or mesh. By combining these different topologies, hybrid networks can take advantage of the strengths of each individual topology while minimizing their weaknesses. Hybrid topologies are often used in larger networks where multiple types of connections are needed to ensure optimal performance and reliability.
Examples of a hybrid network topology
One common example of a hybrid network topology is a star-bus topology. In this topology, multiple star networks are connected to a central bus network. Each star network is connected to a central hub or switch, while the bus network connects these hubs or switches to each other. This topology combines the scalability and fault tolerance of a bus network with the ease of management and reliability of a star network.
Another example of a hybrid network topology is a mesh-star topology. In this topology, multiple mesh networks are connected to a central star network. Each mesh network is fully interconnected with other devices in the mesh, while the star network connects the different mesh networks to each other. This topology provides the flexibility and redundancy of a mesh network, while also allowing for centralized management and easy troubleshooting through the central star network.
Hybrid network topologies can also be used to connect different types of networks, such as local area networks (LANs) and wide area networks (WANs). For example, a WAN may use a mesh network to connect remote sites, while a LAN may use a star network to connect local devices. By combining these two different types of networks, a hybrid network can provide reliable and fast connections between remote and local devices.
Advantages of a hybrid network topology
The main advantage of a hybrid network topology is its flexibility and scalability. By combining different topologies, hybrid networks can be customized to meet the specific needs of an organization. This can result in a network that is easier to manage, more reliable, and more efficient than a single topology network. Additionally, hybrid networks can be expanded easily as needed by adding new topologies or devices, making them ideal for growing organizations.
Disadvantages of a hybrid network topology
However, there are also some disadvantages to using a hybrid network topology. One potential drawback is that hybrid networks can be more complex and difficult to manage than single-topology networks. This can require more resources and expertise to maintain, which may be challenging for smaller organizations or those with limited IT resources.
Another potential issue with hybrid networks is that they can be more expensive to implement than single-topology networks. The cost of purchasing and maintaining multiple types of network hardware and software can be significant, particularly for larger organizations.
Conclusion
In conclusion, a hybrid network topology can be an effective way to build a network that meets the specific needs of an organization. By combining different topologies, hybrid networks can provide flexibility, scalability, and reliability that may not be possible with a single topology network. However, there are also some potential drawbacks to using a hybrid topology, including increased complexity and cost. Organizations should carefully evaluate their needs and resources before deciding whether a hybrid network topology is right for them.
So, in this article, we learned about the different types of network topologies along with their advantages and disadvantages.
