Which type of network topology needs a hub switch and why?

Hubs and Switches in Star Topologies

In this step, we will look at the role of a hub or a switch in a star network.

In this step, we will look at the role of a hub or a switch in a star network.

You will also learn more about how addresses and other fields are added to data that is sent, about the idea of encapsulation, and about how to build an Ethernet frame.

The Ethernet Hub

In the previous step you learned that bus topology was phased out in favour of star topology, which has a central connection point. Initially this was a hub. Each device connected to it using a dedicated UTP cable that linked into one of the hub’s ports.

On its way to the hub, a signal will have picked up some noise. As long as the noise does not cause the signal to cross a threshold level, the hub can recreate each bit, effectively removing the noise. This process is called regeneration. If there is too much noise, errors occur during regeneration: a binary 1 may be regenerated as a binary 0 or vice versa.

Domain 4: Communication and Network Security (Designing and Protecting Network Security)

Eric Conrad, ... Joshua Feldman, in CISSP Study Guide (Third Edition), 2016

Star

Star topology has become the dominant physical topology for LANs. The star was first popularized by ARCNET, and later adopted by Ethernet. Each node is connected directly to a central device such as a hub or a switch, as shown in Figure 5.17.

Figure 5.17. Star Topology

Exam Warning

Remember that physical and logical topologies are related, but different. A logical ring can run via a physical ring, but there are exceptions. FDDI uses both a logical and physical ring, but Token Ring is a logical ring topology that runs on a physical star, for example. If you see the word “ring” on the exam, check the context to see if it is referring to physical ring, logical ring, or both.

Stars feature better fault tolerance: any single local cable cut or NIC failure affects one node only. Since each node is wired back to a central point, more cable is required as opposed to bus (where one cable run connects nodes to each other). This cost disadvantage is usually outweighed by the fault tolerance advantages.

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All About Network Topology—Types and Diagrams

By Staff Contributor on September 24, 2021

Every network has a specific collection of nodes and links that connect them. The arrangement of those nodes and links, or the network topology, informs performance, maintenance costs, and more. You should know the network topology models in use today when designing or managing a network, including the ring, mesh, bus, star, and tree topologies. To effectively manage your network topology, it’s essential to stay on top of your network’s configurations, visually map your network, and monitor its performance.

What Is Network Topology?
Why Is Network Topology Important?
Types of Network Topology

Star Network Topology
Bus Network Topology
Mesh Network Topology
Ring Network Topology
Dual Ring Topology
Tree Network Topology
Hybrid Network Topology

Which Topology Is Best for Your Network?
What Tools Can Help Manage Network Topology?

SolarWinds Network Topology Mapper

Start Mapping Your Network Topology Today

While it’s possible to perform manual topology mapping, you get more for your time with an automated tool. I recommend SolarWinds® Network Topology Mapper (NTM), which offers automated device discovery and can generate detailed and easily digestible network topology maps, allowing you to view and understand your network more quickly and clearly.

What is network topology?

Network topology is the description of the arrangement of nodes (e.g. networking switches and routers) and connections in a network, often represented as a graph.

No matter how identical two organizations are, no two networks are exactly alike. However, many organizations are relying on well-established network topology models. Network topologies outline how devices are connected together and how data is transmitted from one node to another.

A logical network topology is a conceptual representation of how devices operate at particular layers of abstraction. A physical topology details how devices are physically connected.Logical and physical topologies can both be represented as visual diagrams.

A network topology map is a map that allows an administrator to see the physical network layout of connected devices. Having the map of a network’s topology on hand is very useful for understanding how devices connect to each other and the best techniques for troubleshooting.

Types of Topology

There are five types of topology in computer networks:

What is network topology and types of network topology?

Topology is derived from two Greek words topo and logy, where topo means 'place' and logy means 'study'. In computer networks, a topology is used to explain how a network is physically connected and the logical flow of information in the network. A topology mainly describes how devices are connected and interact with each other using communication links.

In computer networks, there are mainly two types of topologies, they are:

1. Physical Topology: A physical topology describes the way in which the computers or nodes are connected with each other in a computer network. It is the arrangement of various elements(link, nodes, etc.), including the device location and code installation of a computer network. In other words, we can say that it is the physical layout of nodes, workstations, and cables in the network.
2. Logical Topology: A logical topology describes the way, data flow from one computer to another. It is bound to a network protocol and defines how data is moved throughout the network and which path it takes. In other words, it is the way in which the devices communicate internally.

Network topology defines the layout, virtual shape, or structure of the network, not only physically but also logically. A network can have one physical topology and multiple logical topologies at the same time.

In this blog, we will mainly concentrate on physical topologies. We'll learn about different types of physical topologies, their advantages, and disadvantages.

In a computer network, there are mainly six types of physical topology, they are:

1. Bus Topology
2. Ring Topology
3. Star Topology
4. Mesh Topology
5. Tree Topology
6. Hybrid Topology

Now let us learn these topologies one by one:

Bus Topology

Bus topology is the simplest kind of topology in which a common bus or channel is used for communication in the network. The bus is connected to various taps and droplines. Taps are the connectors, while droplines are the cables connecting the bus with the computer. In other words, there is only a single transmission line for all nodes.

When a sender sends a message, all other computers can hear it, but only the receiver accepts it(verifying the mac address attached with the data frame) and others reject it. Bus technology is mainly suited for small networks like LAN, etc.

In this topology, the bus acts as the backbone of the network, which joins every computer and peripherals in the network. Both ends of the shared channel have line terminators. The data is sent only in one direction and as soon as it reaches the end, the terminator removes the data from the communication line(to prevent signal bounce and data flow disruption).

In a bus topology, each computer communicates to another computer on the network independently. Every computer can share the network's total bus capabilities. The devices share the responsibility for the flow of data from one point to the other in the network.

For Example Ethernet cable, etc.

Following are the advantages of Bus topology:

1. Simple to use and install.
2. If a node fails, it will not affect other nodes.
3. Less cabling is required.
4. Cost-efficient to implement.

Following are the disadvantages of Bus topology:

1. Efficiency is less when nodes are more(strength of signal decreases).
2. If the bus fails, the network will fail.
3. A limited number of nodes can connect to the bus due to limited bus length.
4. Security issues and risks are more as messages are broadcasted to all nodes.
5. Congestion and traffic on the bus as it is the only source of communication.

Ring Topology

Ring topology is a topology in which each computer is connected to exactly two other computers to form the ring. The message passing is unidirectional and circular in nature.

This network topology is deterministic in nature, i.e., each computer is given access for transmission at a fixed time interval. All the nodes are connected in a closed-loop. This topology mainly works on a token-based system and the token travels in a loop in one specific direction.

In a ring topology, if a token is free then the node can capture the token and attach the data and destination address to the token, and then leaves the token for communication. When this token reaches the destination node, the data is removed by the receiver and the token is made free to carry the next data.

For Example, Token Ring, etc.

Following are the advantages of Ring topology:

1. Easy Installation.
2. Less Cabling Required.
3. Reduces chances of data collision(unidirectional).
4. Easy to troubleshoot(the faulty node does not pass the token).
5. Each node gets the same access time.

Following are the disadvantages of Ring topology:

1. If a node fails, the whole network will fail.
2. Slow data transmission speed(each message has to go through the ring path).
3. Difficult to reconfigure(we have to break the ring).

Star Topology

Star topology is a computer network topology in which all the nodes are connected to a centralized hub. The hub or switch acts as a middleware between the nodes. Any node requesting for service or providing service, first contact the hub for communication.

The central device(hub or switch) has point to point communication link(the dedicated link between the devices which can not be accessed by some other computer) with the devices. The central device then broadcast or unicast the message based on the central device used. The hub broadcasts the message, while the switch unicasts the messages by maintaining a switch table. Broadcasting increases unnecessary data traffic in the network.

In a star topology, hub and switch act as a server, and the other connected devices act as clients. Only one input-output port and one cable are required to connect a node to the central device. This topology is better in terms of security because the data does not pass through every node.

For Example High-Speed LAN, etc.

Following are the advantages of Star topology:

1. Centralized control.
2. Less Expensive.
3. Easy to troubleshoot(the faulty node does not give response).
4. Good fault tolerance due to centralized control on nodes.
5. Easy to scale(nodes can be added or removed to the network easily).
6. If a node fails, it will not affect other nodes.
7. Easy to reconfigure and upgrade(configured using a central device).

Following are the disadvantages of Star topology:

1. If the central device fails, the network will fail.
2. The number of devices in the network is limited(due to limited input-output port in a central device).

Mesh Topology

Mesh topology is a computer network topology in which nodes are interconnected with each other. In other words, direct communication takes place between the nodes in the network.

There are mainly two types of Mesh:

1. Full Mesh: In which each node is connected to every other node in the network.
2. Partial Mesh: In which, some nodes are not connected to every node in the network.

In a fully connected mesh topology, each device has a point to point link with every other device in the network. If there are 'n' devices in the network, then each device has exactly '(n-1)' input-output ports and communication links. These links are simplex links, i.e., the data moves only in one direction. A duplex link(in which data can travel in both the directions simultaneously) can replace two simplex links.

If we are using simplex links, then the number of communication links will be 'n(n-1)' for 'n' devices, while it is 'n(n-1)/2' if we are using duplex links in the mesh topology.

For Example, the Internet(WAN), etc.

Following are the advantages of Mesh topology:

1. Dedicated links facilitate direct communication.
2. No congestion or traffic problems on the channels.
3. Good Fault tolerance due to the dedicated path for each node.
4. Very fast communication.
5. Maintains privacy and security due to a separate channel for communication.
6. If a node fails, other alternatives are present in the network.

Following are the disadvantages of Mesh topology:

1. Very high cabling required.
2. Cost inefficient to implement.
3. Complex to implement and takes large space to install the network.
4. Installation and maintenance are very difficult.

5. Tree Topology:

Tree topology is a computer network topology in which all the nodes are directly or indirectly connected to the main bus cable. Tree topology is a combination of Bus and Star topology.

In a tree topology, the whole network is divided into segments, which can be easily managed and maintained. There is a main hub and all the other sub-hubs are connected to each other in this topology.

Following are the advantages of Tree topology:

1. Large distance network coverage.
2. Fault finding is easy by checking each hierarchy.
3. Least or no data loss.
4. A Large number of nodes can be connected directly or indirectly.
5. Other hierarchical networks are not affected if one of them fails.

Following are the disadvantages of Tree topology:

1. Cabling and hardware cost is high.
2. Complex to implement.
3. Hub cabling is also required.
4. A large network using tree topology is hard to manage.
5. It requires very high maintenance.
6. If the main bus fails, the network will fail.

Hybrid Topology:

A Hybrid topology is a computer topology which is a combination of two or more topologies. In practical use, they are the most widely used.

In this topology, all topologies are interconnected according to the needs to form a hybrid. All the good features of each topology can be used to make an efficient hybrid topology.

Following are the advantages of Hybrid topology:

1. It can handle a large volume of nodes.
2. It provides flexibility to modify the network according to our needs.
3. Very Reliable(if one node fails it will not affect the whole network).

Following are the disadvantages of Hybrid topology:

1. Complex design.
2. Expensive to implement.
3. Multi-Station Access Unit(MSAL) required.

Hence, after learning the various computer network topologies, we can conclude that some points need to be considered when selecting a physical topology:

• Ease of Installation.
• Fault Tolerance.
• Implementation Cost.
• Cabling Required.
• Maintenance Required.
• Reliable Nature.
• Ease of Reconfiguration and upgradation.

This is all about the topology and its types in a computer network. Hope you learned something new today. That's it for this blog.

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Why is this relevant for C2G?

Our network cabling products - copper and fiber - provide the links between the nodes within the topology.

Overview

A network topology describes how computers, printers, and other devices (i.e. nodes) are connected to the network. The following topologies are most commonly used to build most networks.

Bus Topology

A bus topology exists when all of the nodes on the network are connected to a single cable. This single cable is commonly referred to as a backbone. Bus topology was used for early 10Base-2, ThinNet, and 10Base-5, ThickNet, coaxial cable Ethernet networks. In this topology messages sent from a node are broadcast to all nodes on the network. Only the intended recipient node accepts and processes the message. This type of network topology is relatively easy to install and inexpensive. This topology requires that both ends of the backbone cable be terminated. If the backbone is not terminated, then signal is likely to bounce back from the end of the cable causing data collisions and noise that may disrupt the network. The main drawbacks to this type of network topology are a limitation on the amount of computers that can be connected to the network, and the fact that only a single backbone cable is used to connect all of the nodes. Network using a bus topology are limited to only a few dozen computers. If the network exceeds this size performance, problems will likely result. If there is a failure in the backbone cable connecting all of the nodes, then the entire network will become unstable and potentially cease to function. This topology is not typically used in modern networks.

Bus Topology

Ring and Double Ring Topology

A ring topology exists when all of the nodes on the network are connected in a circle. Each node in the network acts as a repeater keeping the signal strong as it travels through the network. A node will generate a signal that is addressed to a specific computer on the network, and then the signal will be sent through the network in either a clockwise or counterclockwise direction. It is important to note that all signals on a network using this type of topology must travel in the same direction. This reduces the amount of data collision and noise on the network. The signal will continue through each node until it reaches the intended destination node. Typically this type of network will use a Token Ring protocol, which allows only one computer to transmit a signal at any given time. The main drawback of this type of topology is that if there is a failure of any of the nodes or cables connecting the nodes, then the network will become unstable and potentially cease to function. The solution to this drawback is a double ring topology. The double ring adds a secondary cable for redundancy in the case of a failure.

Ring Topology

Double Ring Topology

Star and Extended Star Topologies

The star and extended star are the most popular topologies for Ethernet networks. This type network is easy to setup, relatively inexpensive, and provides more redundancy than other topologies, i.e. bus topology. The star topology is configured by connecting all of the nodes on the network to central device. The central connection allows the network to continue functioning even if a single node or cable fails. The major drawback to this topology is that if the central device fails, then the network will become unstable or cease to function. The star topology is most suitable for small, centralized networks. The extended star topology adds sub-central devices that are connect to the central device. This type of topology is advantageous for large networks and provides functionality for the organization and subnetting of the IP address allocation within the network. The extended star topology is most suitable for large networks that may span an entire building.

Star Topology

Extended Star Topology

Tree/Hierarchical

The tree/hierarchical topology is configured by integrating multiple star topologies on a bus topology and using a central "root" node. The major drawback to this topology is that if the "root" node fails, then the network will become unstable or cease to function. This type of topology holds the advantage over a bus or star topology because it is able to better support future expansion of the network. However, this type of network is not commonly used because of the vulnerability of the topology.

Tree/Hierarchical Topology

Mesh Topology

This topology is divided into two different types; full-mesh and partial mesh. A full mesh topology provides a connection from each node to every other node on the network. This provides a fully redundant network and is the most reliable of all networks. If any link or node in the network fails, then there will be another path that will allow network traffic to continue. The major drawback to this type of network is the expense and complexity required to configure this topology. This type of topology is only used in small networks with only a few nodes. A partial mesh topology provides alternate routes from each node to some of the other nodes on the network. This type of topology provides some redundancy and is commonly used in backbone environments, networks where services are vital, and in wide area networks, WANs. The most notable partial mesh network is the Internet.

Mesh Topology

Partial Mesh Topology

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What is Topology?

Network topologies describe the methods in which all the elements of a network are mapped. The topology term refers to both the physical and logical layout of a network.

In this network topology tutorial, we will explain:

• What is Topology?
• Type of Network Topology
• Point to Point
• Bus Topology
• Ring Topology
• Star Topology
• Mesh Topology
• Tree Topology
• Hybrid Topology
• How to select a Network Topology?