What is topology? What is meant by the topology of the local network

The term "topology" has a lotvalues, one of which is used in the computer world to describe networks. What is the topology of computer networks, and will be discussed later. But, a little forward, in the simplest case, this concept can be considered as a description of the configuration (location) of computers connected to the network. In other words, it all comes down to understanding not even the connections themselves, but geometric figures that correspond to each type of terminal location.

What is meant by the topology of the local network?

As it is already clear, computers that are united into unified networks are connected to them not chaotically, but in a strictly defined order. To describe this scheme, an understanding of topology was introduced.

In fact, what is topology? Map, diagram, diagram, map. Descriptive process, as already understood, in something akin to elementary knowledge of geometry. However, only purely from the geometric point of view, this term can not be considered. Since it is not only about connections, but also about the transfer of information, this factor should also be taken into account.

Main types of networks and their topologies

In general, the single notion of computer topology is notexist. It is generally accepted that there can be several types of topologies that collectively describe one or another network organization. Actually, networks can be completely different.

For example, the simplest form of organizationconnection of several computer terminals into a single whole can be called a local network. There are still intermediate types of networks (urban, regional, etc.).

Finally, the largest are global networks that affect large geographic regions and include all other types of networks, as well as computers and telecommunications equipment.

But what is meant by the topology of the local network, as one of the simplest forms of organizing the connection of several computers among themselves, in this case?

On the basis of the described processes and structures, they are divided into several types:

• Physical - a description of the existing structure of the location of computers and nodes of the network, taking into account the relationships between them;
• logical - the description of the passage of the signal through the network;
• information - a description of the movement, direction and redirection of data within the network;
• exchange management - a description of the principle of using or transferring rights to use the network.

Network Topology: types

Now a few words about the generally acceptedClassification of types of topologies by links. In the context of what a topology is, it is worth mentioning another type of classification that describes only the way the computer connects to the network or the principle of its interaction with other terminals or main nodes. In this case, the concepts of fully connected and incompletely connected topologies become topical.

A fully bonded structure (and this is recognized throughoutworld) is extremely cumbersome due to the fact that each single terminal that is part of a single network structure is connected to all the others. The disadvantage in this case is that for each computer it is necessary to install additional communication equipment, and the terminal itself must be equipped with a sufficiently large number of communication ports. And as a rule, such structures, if applicable, are extremely rare.

The loose topology in this plan looks likeis much preferable, since each individual terminal does not connect to all other computers, but receives or transmits information through specific network nodes or refers directly to a central hub or hub. A striking example of this is the topology of the "star" network.

Since it was about the basic methodsthe connection of terminals into a single whole (network), one should dwell on the basic topologies of all the main types, among which the main are "bus", "star" and "ring", although there are some mixed types.

Network topology "bus"

This type of connection of terminals to the network is quite popular, although it has very serious drawbacks.

Consider what a topology is"Bus", you can on a simple example. Imagine a cable with several branches on either side. At the end of each such branch is a computer terminal. They are not directly connected to each other, but the information is received and transmitted through a single trunk, at both ends of which special terminators are installed that prevent reflection of the signal. This is the standard linear network topology.

The advantage of such a connection is thatthe length of the main highway is significantly reduced, and the output of a single terminal is not affected by the network as a whole. The main drawback is that when the bus itself is disrupted, the entire network is unworkable. In addition, the topology of the "bus" is limited in the number of connected workstations and has a fairly low performance due to the allocation of resources between all terminals in the network. The distribution can be uniform or uneven.

The star topology (star)

The topology of the "star" network in a senseresembles a "bus", with the only difference that all terminals are connected to a central switchgear (hub) rather than to a single mainline.

Just through the hub, all computers caninteract with each other. Information is transferred from the hub to all devices, but it is received only by those to which it is intended. The advantages of such a connection include the possibility of centralized management of all network terminals, as well as the connection of new ones. However, as with the "bus", the failure of the central switching device is fraught with consequences for the entire network.

Topology "ring" (ring)

Finally, we have another type of connection -ring topology of the network. As, probably, it is already clear from the title, the connection of computers is carried out sequentially from one to another through intermediate nodes, as a result of which a closed circle is formed (naturally, the circle in this case is a conditional concept).

When sending information from the starting pointpasses through all the terminals that face the final recipient. But the final beneficiary is recognized on the basis of marker access. That is, the information received is only a terminal marked in the information stream. This scheme is almost never used because the failure of one computer automatically entails a disruption in the operation of the entire network.

Mesh and mixed topology

This type of connection can be obtained by removing some links from the above connections or adding them in addition. In most cases, this scheme is used in large networks.

In this regard, you can define severalbasic derivatives. The most common are schemes like "double ring", "tree", "lattice", "snowflake", "network Klosa", etc. As can be seen even from the names, all these are variations on the theme of the main types of connections that are taken for the basis.

There is also a mixed type of topology, which can combine several other (subnets), grouped by some characteristic features.

Conclusion

Now, probably, it is clear what istopology. If we make a general summary, this concept is a description of how to connect the computers in the network and the interaction between them. How this is done depends solely on the method of integrating the terminals into one whole. And to say that today it is possible to single out one universal connection option, it is impossible. In each case and depending on the needs, one or another type of connection can be used. But in local networks, if we talk about them, the most common is the "star" scheme, although the "bus" is still widely used.

It remains to add that in the network topology,to meet still notions of centralization and decentralization, but they are mostly connected not with connections, but with a network terminal management system and exercising control over them. Centralization is clearly expressed in "star" connections, but decentralization is also applicable for this type, providing the input of additional elements in order to increase the reliability of the network when the central switch fails. A sufficiently effective development in this respect is the "hypercube" scheme, but it is very difficult to develop.