Topology of a network

Topology of a network

Topology of a network. Theoretical approach to network design

I talked with my niece last week, she asked me what I was working on, and I told her that a friend was trying to open a branch of her business in Amsterdam and requested collaboration for the assembly of the business network infrastructure. I had to travel to know the place and there he told me all his needs. I didn’t give her many details about it but she asked me: what is a network?

To answer this question I will write several publications and in this post we will see the different types of topologies of known networks that exist, I will write it in a simple way without so many technicalities so that my niece does not fall asleep to the third paragraph.

What is the topology of a network?

The topology of a network is the way in which connections are made between two or more nodes, either in the physical plane, or in the logical plane. The wiring, the configuration of the protocols and the types of nodes are part of the architecture and not of the topology, but I will talk about this later. So:

  • Physical topology: applies to physical wiring connections.
  • Logical topology: applies to the logical connections of protocols that make the network work.

Point to point networks

It is a permanent link between two end points or nodes. It is the basic topology used in conventional telephony and long range networks (WAN).

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Pros:

The advantage is the communication without obstacles between the two endpoints and is very easy to configure. It is a low cost system since no network devices or dedicated servers are needed. Wiring costs depend on the number of links between the stations. Each node has at least two interfaces.

Cons:

All devices can be a client and/or server, so their administration cannot be centralized. They are not safe or scalable systems.

Networks in bus or linear topology

A network in bus topology is one that has a single means of communication to which all the equipments are connected.

In a bus topology, each node is connected to a common network cable segment that is placed as a linear bus, that is, a long cable that extends from one end to the other. The cable can be coaxial, twisted pair or fiber optic.

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Pros:

Its main advantage is easy implementation and growth capacity.

Cons:

This type of network is effective for connections between the nodes that are located in the center, but it is not effective for those that are located at the extreme ends since the information is very likely to collide with the sending of information from another computer.

Networks in ring topology

In the ring topologies we find that each node of the network is connected only to the previous node and the subsequent node, so that the chain of nodes is closed forming a ring.

To send information you have to go through each of the nodes because it is read and forwarded by all of them.

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Traffic circulates in one direction, so to send information to a computer located a node behind, the sending will take almost a full turn in the network. To minimize this problem, the double ring topology is usually used, so that one link or another can be used depending on the direction to which we want to send the information.

To resolve disputes in connectivity and determine what it is transmitting and when it will use a Media Access Control Protocol (MAC, Media Access Control) that can be slot, token, and record insertion.

A node will only transmit the information when it has the token, while the rest of the time it will retransmit the information it receives from the previous node to the next node.

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Pros:

It is a simple topology. To add a node, you have to connect it with two other nodes. The system provides equitable access to all nodes where each device has access to the token and the opportunity to transmit. It has better performance than a bus topology. It does not require a central node to manage connectivity between devices.

Cons:

Performance declines as the network grows because the nodes have to wait longer to receive the token, it does not do so much as a bus topology.

If a node fails, then the network fails completely, the nodes cannot be isolated and the detection and resolution of problems is very difficult because we simply see the network falling.

Another point to keep in mind is that the transmitted information will be seen by all the nodes of the network, so that a major privacy problem is generated.

Star topology networks

A star topology is a network where all equipment is connected to a single central point.

This central point will be responsible for managing each connection and distributing the traffic, avoiding collisions and ensuring maximum efficiency in communications.

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Pros:

The main advantages of this type of networks are its simplicity of implementation and ease of growth. Simply connect the new equipment to the central node without having to act on the rest of the network.

It is easy to isolate equipment with problems in case of failure. On the other hand, total centralization facilitates administrative changes and allows configurations throughout the network from a single remote management point. This topology is the most used as the basis for the design of local area networks.

Cons:

It takes a lot of wiring. In case of failure of the central node, the entire network goes down.

Networks in hybrid or mixed topologies

Networks in hybrid or mixed topologies are those that have basic topologies in their structure. Thus, even if they use the basic topologies, they cannot be classified as such.

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Each network topology has its advantages and disadvantages, so not all of them are applicable to all solutions. Really, the perfect conditions are not usually available to be able to directly apply a specific topology, so network designers find it necessary to adopt mixed solutions where combinations of the basic options are used.

At this point, the result cannot be categorized as a specific topology, so they fall into the category of hybrid topologies. Although hybrid topologies by definition can have multiple configurations, there are some with specific characteristics.

Networks in tree topologies

Tree topology networks are a succession of small star topologies connected to each other without a single central node.

In a local area network it is very easy to find the tree topology, especially if it incorporates different physical areas, floors of a building or several buildings in the same area.

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Pros:

It is a topology supported by a multitude of software and hardware vendors. It has an easy problem solving.

Cons:

Its configuration entails some difficulty. A lot of wiring is required and the size of each segment is determined by the type of cable used. If the main segment falls, then the entire segment also falls. Similarly, if a node is disconnected, all those connected to it will be disconnected as well.

Networks in mesh topologies

In networks in mesh topologies the equipment is connected to each other as if they were a ring topology, but the connection pattern is not limited to the equipment nor does it have to be closed in a ring.

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A full mesh network topology

It is a mesh topology in which there is a point-to-point link between all terminals. These types of networks are widely used by large telecommunications operators to provide WAN service, although it is not mandatory and we can design any type of topology based on our needs and preferences.

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Pros:

Mesh networks may dispense with manual routing, or hardly require attention for maintenance. If any of the links between two adjacent nodes fails, then the adjacent nodes will propagate a change in the route table, notifying the adjacent nodes that there was a change in the network.

Cons:

This network topology implies the use of a greater amount of resources, therefore the cost may rise.

How do you choose a network topology?

That’s what my niece asked me after telling her all the above. When traveling to Amsterdam I met the building where my friend’s company branch will work and explained his needs in more detail, surfing the Internet, using email, cloud storage and videoconferencing were a crucial need.

The initial distribution was in a single plant, but in the future they would be two more plants so that the star topology fulfilled the conditions due to its simplicity in addition to its ease of assembly and maintenance. Each plant would have a star topology and the building would be completed in a hybrid network of the tree type linked with fiber optics. Here my niece interrupted me and asked me about the fiber and with a masterful talent I dodged the ball and continued saying that the design of a network does not end here, aspects such as wiring paths, number of splices, connections and devices must be considered net. As the installation will be carried out in several stages, a detailed plan, a list of materials with their costs etc. would be necessary, but I will continue in another post because my niece has already dispersed and started to see Instagram…

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