Throughput speed. Bandwidth in IP networks: calculation and selection of network equipment. Calculation using programs

04.05.2020

Bandwidth- a metric characteristic showing the ratio of the maximum number of passing units (information, objects, volume) per unit of time through a channel, system, node.

Used in various fields:

in communications and computer science, P.S. is the maximum achievable amount of passing information;
in transport PS - the number of transport units;
in mechanical engineering - the volume of passing air (oil, grease).

It can be measured in various, sometimes very specialized, units - pieces, bits/sec, tons, cubic meters, etc.

In computer science, the definition of throughput usually applies to a communication channel and is defined as the maximum amount of information transmitted or received per unit of time.
Bandwidth is one of the most important factors from a user's point of view. It is estimated by the amount of data that the network can, in the limit, transfer per unit of time from one device connected to it to another.

Channel capacity

The highest possible information transmission speed in a given channel is called its throughput. Channel capacity is the speed of information transmission when using the “best” (optimal) source, encoder and decoder for a given channel, so it characterizes only the channel.

Throughput of a discrete (digital) channel without interference

C = log(m) bits/symbol

where m is the base of the signal code used in the channel. The speed of information transmission in a discrete channel without noise (ideal channel) is equal to its capacity when the symbols in the channel are independent and all m symbols of the alphabet are equally probable (used equally often).

Neural Network Bandwidth

The throughput of a neural network is the arithmetic average between the volumes of processed and created information neural network per unit of time.

Table of pipe capacity for liquids, gas, water vapor.

Type of liquid	Speed (m/sec)
City water
Water pipeline
Central heating water
Pressure system water in pipeline line
Hydraulic fluid	up to 12m/sec
Oil pipeline line
Oil in the pressure system of the pipeline line
Steam in the heating system
Steam central piping system
Steam in a high temperature heating system
Air and gas in the central piping system

Most often, ordinary water is used as a coolant. The rate of decrease in throughput in pipes depends on its quality. The higher the quality of the coolant, the longer the pipeline made of any material (steel, cast iron, copper or plastic) will last.

Calculation of pipe capacity.

For accurate and professional calculations, it is necessary to use the following indicators:

The material from which pipes and other elements of the system are made;
Pipe length
Number of water consumption points (for water supply system)

The most popular calculation methods:

1. Formula. A rather complex formula, which is understandable only to professionals, takes into account several values at once. The main parameters that are taken into account are the material of the pipes (surface roughness) and their slope.

2. Table. This is a simpler way by which anyone can determine the throughput of a pipeline. An example is the engineering table of F. Shevelev, from which you can find out the throughput capacity based on the pipe material.

3. Computer program. One of these programs can be easily found and downloaded on the Internet. It is designed specifically to determine the throughput for pipes of any circuit. In order to find out the value, you need to enter initial data into the program, such as material, pipe length, coolant quality, etc.

It should be said that the latter method, although the most accurate, is not suitable for calculating simple household systems. It is quite complex and requires knowledge of the values of a wide variety of indicators. To calculate a simple system in a private house, it is better to use tables.

An example of calculating pipeline capacity.

Pipeline length is an important indicator when calculating throughput. The length of the pipeline has a significant impact on throughput indicators. The greater the distance water travels, the less pressure it creates in the pipes, which means the flow speed decreases.

Here are some examples. Based on tables developed by engineers for these purposes.

Pipe capacity:

0.182 t/h with a diameter of 15 mm
0.65 t/h with pipe diameter 25 mm
4 t/h with a diameter of 50 mm

As can be seen from the examples given, a larger diameter increases the flow rate. If the diameter is doubled, the throughput will also increase. This dependence must be taken into account when installing any liquid system, be it plumbing, drainage or heat supply. This is especially true for heating systems, since in most cases they are closed, and the heat supply in the building depends on the uniform circulation of the liquid.

Internet channel bandwidth or, more simply put, Internet speed, represents the maximum number of data received by a personal computer or transmitted to the Network in a certain unit of time.

Most often you can find a measurement of data transfer speed in kilobits/second (Kbps; Kbps) or in megabits (Mbps; Mbps). File sizes are usually always specified in bytes, KB, MB and GB.

Since 1 byte is 8 bits, in practice this will mean that if the speed of your Internet connection is 100 Mbps, then the computer can receive or transmit no more than 12.5 Mb of information per second (100/8 = 12.5). This is simpler. can be explained in this way, if you want to download a video whose volume is 1.5 Gb, then it will take you only 2 minutes.

Naturally, the above calculations were made under ideal laboratory conditions. For example, the reality may be completely different:

Here we see three numbers:

Ping – this number means the time it takes to transmit Network Packets. The smaller the value of this number, the better quality Internet connection (preferably the value should be less than 100ms).
Next comes the speed of receiving information (incoming). This is exactly the number that Internet providers offer when connecting (it is for this number of “Megabits” that you have to pay your hard-earned dollars/hryvnia/rubles, etc.).
The third number remains, indicating the information transfer speed (outgoing). Naturally, it will be less than the speed of receiving data, but providers are usually silent about this (although, in fact, a higher outgoing speed is rarely required).

What determines the speed of an Internet connection?

The speed of the Internet connection depends on the tariff plan set by the provider.
The speed is also affected by the technology of the information transmission channel and the load on the Network by other users. If the overall channel capacity is limited, then the more users are on the Internet and the more information they download, the more the speed drops, since there is less “free space” left.
There is also a dependence on the loading speed of the sites you access. For example, if at the time of loading the server can provide data to the user at a speed of less than 10 Mbit/sec, then even if you have a maximum connection tariff plan, you won't achieve more.

Factors that also affect Internet speed:

When checking, the speed of the server you are accessing.
Setup and speed Wi-Fi router, if you are connected to the local network through it.
At the time of scanning, all programs and applications running on the computer.
Firewalls and antiviruses that run in the background.
Your settings operating system and the computer itself.

How to increase internet speed

If there is malware or unwanted software on your computer, then this may affect the speed of your Internet connection. Trojans, viruses, worms, etc. that get into the computer can take part of the channel bandwidth for their needs. To neutralize them, you must use anti-virus applications.

If you use Wi-Fi that is not password protected, then other users will usually connect to it and are not averse to using free traffic. Be sure to set a password to connect to Wi-Fi.

Parallel running programs also reduce speed. For example, simultaneous download managers, Internet messengers, automatic update operating system leads to an increase in processor load and therefore the speed of the Internet connection decreases.

These actions, in some cases, help increase Internet speed:

If you have a high Internet connection, but the speed leaves much to be desired, increase the port bandwidth. This is quite easy to do. Go to the “Control Panel”, then to “System” and to the “Hardware” section, then click on “Device Manager”. Find “Ports (COM or LPT)”, then expand their contents and look for “Serial port (COM 1)”.

After that you click right click mouse and open "Properties". After this, a window will open in which you need to go to the “Port parameters” column. Find the “Speed” parameter (bits per second) and click on the number 115200 – then OK! Congratulations! Now your port throughput speed has been increased. Because the default speed is set to 9600 bps.

To increase speed, you can also try disabling the QoS packet scheduler: Run the gpedit.msc utility (Start - Run or Search - gpedit.msc). Next: Computer Configuration - Administrative Templates - Network - QoS Packet Scheduler - Limit reserved bandwidth - Enable - set to 0%. Click "Apply" and restart the computer.

There are very favorable rates hosting for hosting a website. But sometimes they scare you with restrictions on traffic volume. Let's figure out how to determine whether the site will fit into established framework.

Bandwidth Calculation

A simple calculation can tell you a lot of interesting things:
Required traffic = average number of page views x average page weight x average number of visitors per day x number of days in a month x reserve.
The average number of visitors per day is the total number of visitors per month, divided by 30.

Average page weight is the average size of a single page file.
Average Page Views is the average number of page views per visitor.
Reserve is a safety factor that varies between 1.3-1.8.

We put the numbers together and get a rough estimate of the bandwidth your site requires.

Calculation of the bandwidth of the site from which you can download a file

The calculation is carried out in a similar way, only you will need to determine additional channels for loading. Website and download throughput is easily calculated using the formula:
Traffic needed = [(Average page views x average page weight x average daily visitors) + (average daily downloads x average file size)] x number of days in a month x reserve.
Average number of visitors per day - this is the total number of visitors per month divided by 30

Average page weight is the average size of a single page file
Average page views is the average number of page views per visitor
Average file size is the total size of the site's files divided by the number.
Reserve is a safety factor that varies between 1.3 - 1.8.

Excess Bandwidth

Now you understand that there is a certain safety margin, ranging from 30% to 80%, which is used in calculating throughput. The reason for this is that reserve capacity is critical, if necessary, to withstand sharp jumps traffic.

That is, the higher the reserve indicator, the more stable the server. This means that it can cope with an unexpected surge in traffic that can erase all the differences between a successful and unsuccessful website advertising campaign.

For example, your article appeared on the first page of Google for search query"iphone" - and the server cannot cope with the sharp increase in traffic. This is how a good advertising campaign suddenly ended very unsuccessfully.

How can you tell if your site needs more bandwidth?

Typically, if a site is constantly busy and slow, this is the first sign that more bandwidth is needed.

The possibility that the provider simply does not have enough reserve bandwidth is also possible. To solve this problem, you need to increase your bandwidth, or switch to a dedicated server, since here you will not need to share the site’s bandwidth with other hosting clients.

In addition, you can use file hosting services, which not only allows you to save an impressive amount of website bandwidth, but also make a profit for downloading your files.

Conclusion

When choosing a suitable hosting plan, you should pay special attention to some other details in addition to the amount of bandwidth.

Processor frequency, number of databases, RAM- this is just an incomplete list. In fact, without high-quality resources for these parameters, unlimited bandwidth loses its meaning.

Do you want to know how the choice of domain affects the position of the site in search results? .

1.What is the process of information transfer?

Transfer of information- a physical process through which information is moved in space. We recorded the information on a disk and moved it to another room. This process characterized by the presence of the following components:

A source of information. Information receiver. Information carrier. Transmission medium.

Information transmission scheme:

Source of information – information channel – receiver of information.

Information is presented and transmitted in the form of a sequence of signals and symbols. From the source to the receiver, the message is transmitted through some material medium. If technical means of communication are used in the transmission process, they are called information transmission channels (information channels). These include telephone, radio, TV. Human sense organs play the role of biological information channels.

The process of transmitting information technical channels communication proceeds according to the following scheme (according to Shannon):

The term “noise” refers to various types of interference that distort the transmitted signal and lead to loss of information. Such interference primarily occurs due to technical reasons: poor quality of communication lines, insecurity of different streams of information transmitted over the same channels from each other. Used for noise protection different ways, for example, the use of various kinds of filters that separate the useful signal from the noise.

Claude Shannon developed a special coding theory that provides methods for dealing with noise. One of the important ideas of this theory is that the code transmitted over the communication line must be redundant. Due to this, the loss of some part of the information during transmission can be compensated. However, the redundancy should not be too large. This will lead to delays and increased communication costs.

2. General scheme of information transfer

3.List the communication channels you know

Communication channel (English channel, data line) - system technical means and a signal propagation medium for transmitting messages (not just data) from source to destination (and vice versa). A communication channel, understood in a narrow sense (communication path), represents only the physical medium of signal propagation, for example, physical line communications.

Based on the type of distribution medium, communication channels are divided into:

wired; acoustic; optical; infrared; radio channels.

4. What are telecommunications and computer telecommunications?

Telecommunications(Greek tele - into the distance, far away and lat. communicatio - communication) is the transmission and reception of any information (sound, image, data, text) over a distance via various electromagnetic systems (cable and fiber optic channels, radio channels and other wired and wireless channels communications).

Telecommunications network is a system of technical means through which telecommunications are carried out.

Telecommunication networks include:

1. Computer networks (for data transmission)

2. Telephone networks (transmission of voice information)

3. Radio networks (transmission of voice information - broadcast services)

4. Television networks (voice and image - broadcast services)

Computer telecommunications - telecommunications, terminal devices which are computers.

The transfer of information from computer to computer is called synchronous communication, and through an intermediate computer, which allows messages to be accumulated and transmitted to personal computers as requested by the user - asynchronous.

Computer telecommunications are beginning to be introduced into education. IN higher school they are used for coordination scientific research, prompt exchange of information between project participants, distance learning, consultations. In the school education system - to increase the efficiency of students’ independent activities related to various types of creative work, including educational activities, based on the widespread use of research methods, free access to databases, and exchange of information with partners both within the country and abroad.

5. What is the bandwidth of an information transmission channel?

Bandwidth- metric characteristic, showing the ratio maximum number of passing units ( information, objects, volume ) per unit of time through a channel, system, node.

In computer science, the definition of bandwidth is usually applied to a communication channel and is determined by the maximum amount of information transmitted/received per unit of time.

Bandwidth is one of the most important factors from a user's point of view. It is estimated by the amount of data that the network can, in the limit, transfer per unit of time from one device connected to it to another.

The speed of information transfer depends largely on the speed of its creation (source performance), encoding and decoding methods. The highest possible information transmission speed in a given channel is called its throughput. The channel capacity, by definition, is

the information transmission rate when using the “best” (optimal) source, encoder and decoder for a given channel, so it characterizes only the channel.

5. In what units is the capacity of information transmission channels measured?

Can be measured in various, sometimes very specialized, units - pieces, bits/sec, tons, Cubic Meters etc.

6. Classification of computer communication channels (by coding method, by communication method, by signal transmission method)

broadcast networks; networks with transmission from node to node.

7. Characteristics of cable channels for transmitting information (coaxial cable, twisted pair, telephone cable, fiber optic cable)

wired – telephone, telegraph (air) communication lines; cable – twisted pair copper, coaxial, fiber optic;

and also based on electromagnetic radiation:

radio channels terrestrial and satellite communications; based on infrared rays.

cables based on twisted pairs copper wires; coaxial cables (central core and copper braid); fiber optic cables.

Cables based twisted pairs

Cables based on twisted pairs are used to transmit digital data and are widely used in computer networks. It is also possible to use them to transmit analog signals. Twisting the wires reduces the influence of external noise on useful signals and reduces radiated electromagnetic vibrations into external space. Shielding increases the cost of the cable, complicates installation and requires high-quality grounding. In Fig. A typical UTP design based on two twisted pairs is presented.

Rice. Cable design with unprotected twisted pair.

Depending on the presence of protection - an electrically grounded copper braid or aluminum foil around twisted pairs, the types of cables based on twisted pairs are determined:

unprotected twisted pair UTP (Unshielded twisted pair) – there is no protective shield around an individual pair;

foil twisted pair FTP (Foiled twisted pair) – there is one common external shield in the form of foil;

protected twisted pair STP (Shielded twisted pair) – there is a protective screen for each pair and a common external screen in the form of a mesh;

foil shielded twisted pair S/FTP (Screened Foiled twisted pair) – there is a protective screen for each pair in foil braid and an outer screen made of copper braid;

unprotected shielded twisted pair SF/UTP (Screened Foiled Unshielded twisted pair) – double external shield made of copper braid and foil, each twisted pair without protection.

1.5.2.2. Coaxial cable

The purpose of a coaxial cable is signal transmission in various fields of technology: communication systems; broadcast networks; computer networks; antenna-feeder systems of communication equipment, etc. This type of cable has an asymmetrical design and consists of an internal copper core and braid, separated from the core by an insulation layer.

A typical coaxial cable design is shown in Fig. 1.22.

Rice. 1.22. Typical coaxial cable design

Thanks to the metal shielding braid, it has high noise immunity. The main advantage of coax over twisted pair is its wide bandwidth, which provides potentially higher data transfer rates of up to 500 Mbps compared to twisted pair cables. In addition, coaxial provides significantly greater permissible signal transmission distances (up to a kilometer), it is more difficult to mechanically connect to it for unauthorized wiretapping of the network, and it also pollutes the environment significantly less with electromagnetic radiation. However, installation and repair of coaxial cable is more difficult than twisted pair cable, and the cost is higher.

It uses conventional LED transceivers, which reduces cost and increases service life compared to single-mode cable. In Fig. 1.24. The characteristic of signal attenuation in optical fiber is given. Compared to other types of cables used for communication lines, this type of cable has significantly lower signal attenuation values, which usually range from 0.2 to 5 dB per 1000 m of length. Multimode optical fiber is characterized by attenuation transparency windows in the wavelength ranges 380-850, 850-1310 (nm), and single-mode fiber, respectively, 850-1310, 1310-1550 (nm).

Figure 1.24. Fiber transparency windows.

Advantages of fiber optic communication:

Wide bandwidth.

Extremely conditioned high frequency carrier vibration. When using the technology of spectral multiplexing of communication channels using the wave

Multiplexing in 2009, signals from 155 communication channels with a transmission speed of 100 Gbit/s each were transmitted over a distance of 7,000 kilometers. Thus, the total data transfer rate over optical fiber was 15.5 Tbit/s. (Tera = 1000 Giga);

Low attenuation of the light signal in the fiber.

Allows you to build long-length fiber-optic communication lines without intermediate signal amplification;

Low noise level in fiber optic cable.

Allows you to increase the bandwidth by transmitting various modulations of signals with low code redundancy;

High noise immunity and protection from unauthorized access.

It provides absolute protection of the optical fiber from electrical interference, interference and a complete absence of radiation into the external environment. This is explained by the nature of light vibration, which does not interact with electromagnetic fields of other frequency ranges, like the optical fiber itself, which is a dielectric. By exploiting a number of light propagation properties in fiber optics, optical link integrity monitoring systems can instantly shut down a compromised link and sound an alarm. Such systems are especially necessary when creating communication lines in government, banking and some other special services that have increased requirements for data protection;

No need for galvanic isolation of network nodes.

Fiber optic networks fundamentally cannot have electrical ground loops, which occur when two network devices have grounding connections at different points of the building;

 High explosion and fire safety, resistance to aggressive environments.

Due to the absence of the possibility of sparking, optical fiber increases network security at chemical and oil refineries, when servicing high-risk technological processes;

 Light weight, volume, cost-effectiveness of fiber optic cable.

The fiber is based on quartz (silicon dioxide), which is a widely available inexpensive material. Currently, the cost of fiber relative to a copper pair is 2:5. The cost of the fiber optic cable itself is constantly decreasing, but the use of special optical receivers and transmitters (fiber optic modems) that convert light signals into electrical signals and vice versa significantly increases the cost of the network as a whole;

 Long service life.

The service life of optical fiber is at least 25 years. Fiber optic cable also has some disadvantages. The main one is the high complexity of installation. When connecting the ends of the cable, it is necessary to ensure high accuracy of the cross-section of the fiberglass, subsequent polishing of the cut and alignment of the fiberglass when installed in the connector. Installation of connectors is carried out by welding the joint or by gluing using a special gel that has the same refractive index of light as fiberglass. In any case, this requires highly qualified personnel and special tools. In addition, fiber optic cable is less durable and less flexible than electrical cable, and is sensitive to mechanical stress. It is also sensitive to ionizing radiation, which reduces the transparency of the glass fiber, that is, increases the signal attenuation in the cable. Sudden temperature changes can cause fiberglass to crack. To reduce the influence of these factors, various design solutions are used, which affects the cost of the cable.

Taking into account the unique properties of optical fiber, telecommunications based on it are increasingly used in all areas of technology. These are computer networks, city, regional, federal, as well as intercontinental underwater primary communication networks, and much more. Using fiber optic communication channels, the following is carried out: cable TV, remote video surveillance, video conferences and video broadcasts, telemetry and other information systems.

8. Characteristics wireless channels information transmission (satellite,

radio channels, Wi-Fi, Bluetooth)

Wireless technologies- subclass information technologies, serve to transmit information over a distance between two or more points, without requiring their connection by wires. Can be used to transmit informationinfrared radiation, radio waves, optical or laser radiation.

Currently there are many wireless technologies, most commonly known to users by their marketing names such as Wi-Fi, WiMAX, Bluetooth. Each technology has certain characteristics that determine its scope of application.

There are different approaches to classifying wireless technologies.

By range:

o Wireless Personal Area Networks ( WPAN - Wireless Personal Area Networks). Examples of technologies are Bluetooth.

o Wireless local networks ( WLAN - Wireless Local Area Networks).

Examples of technologies are Wi-Fi.

o City-scale wireless networks ( WMAN - Wireless Metropolitan Area Networks). Examples of technologies are WiMAX.

o Wireless global networks ( WWAN - Wireless Wide Area Network).

Examples of technologies are CSD, GPRS, EDGE, EV-DO, HSPA.

By topology:

o "Point-to-point".

o "Point-to-multipoint".

By area of application:

o Corporate (departmental) wireless network- created by companies for their own needs.

o Operator wireless networks - created by telecom operators to provide services for a fee.

A short but concise way of classification can be to simultaneously display the two most significant characteristics of wireless technologies on two axes: maximum information transfer speed and maximum distance.

Tasks Task 1. In 10 s, 500 bytes of information are transmitted over the communication channel. What is it equal to

channel capacity? (500/10=50 bytes/s=400bit/s)

Task 2. How much information can be transmitted over a channel with a bandwidth of 10 kbit/s in 1 minute? (10 kbit/s*60 s = 600 kbit)

Problem 3. The average data transfer speed using a modem is 36864 bps. How many seconds will it take for the modem to transmit 4 pages of text in KOI-8 encoding, assuming that each page has an average of 2304 characters.

Solution: Number of characters in the text: 2304*4 = 9216 characters.

In KOI-8 encoding, each character is encoded as one byte, then the information volume of the text is 9216 * 8 = 73,728 bits.

Time = volume / speed. 73728: 36864 = 2 s