Transformers tsp, tszp and tszps. Resistance thermal converters. characteristics, decoding of the symbol of resistance thermal converters TSM, TSP, TSP, TSM, Metran What is it on a TSP car

These days, bank cards are no longer a rarity, and each of us no longer makes one or two transactions per quarter, but three or four daily. Tens of millions of cards issued, hundreds of thousands of transactions per hour, tens of thousands of terminal devices for accepting cards - this is today’s reality. There is a steady trend of shifting the emphasis from cash receipt transactions towards payment transactions for goods/services in trade and service enterprises (hereinafter referred to as TSPs).
Let us briefly recall what the general procedure for paying by card at merchants looks like.

The client (card holder) makes a purchase of a product or service at a merchant that accepts cards for payment, as evidenced by stickers at the entrance to the store premises or at the checkout. Approaching the cashier, the client presents the card and informs the seller that he intends to pay with it. The seller takes the card and conducts an initial check to ensure there are no obvious signs of counterfeit (he does not have to be an expert, he just needs to make sure that it is clearly not counterfeit). Next, the seller reads the data from the magnetic stripe or microprocessor (chip) of the card, using the corresponding connector of the electronic terminal (hereinafter referred to as ET). Then he enters the transaction amount, ET generates an authorization request and sends it to the acquiring bank. Next, the authorization request via the MPS channel reaches the host of the issuing bank, which allows or prohibits the execution of this operation (transaction). If the transaction is authorized, the issuer issues an authorization code and a response code (RC) '00'. Otherwise, the issuer's response is different from '00' and the authorization code is not issued (the transaction is not approved; the issuer does not confirm payment). Upon positive completion, the merchant merchant prints two copies of the check and the client confirms his agreement to pay for the transaction, either by signing the check (signature-based transaction, SBT), or by entering a PIN (PIN-based transaction, PBT). With SBT, the merchant must complete the transaction by matching the signature on the check with the customer's sample signature in the designated area on the back of the card.

Posting information for buyers

Let's start with the fact that each merchant, by sticking posters with MPS logos on its doors, thereby assumes an obligation (precisely an obligation, and not just a wish) to accept cards of the corresponding system for payment.

Processing payment transactions using bank cards in trade and service enterprises

And if the MasterCard logo hangs at the cash register, then this merchant is obliged to accept the corresponding card for payment (but not a Visa card, and vice versa). Moreover, in merchant outlets that accept cards, in places accessible to customers (“buyer’s corner”), information should be posted explaining the policy of this point regarding the return and exchange of goods paid for by card. The absence of such information resource is a violation of the rules of the Ministry of Railways.

Cashier's reluctance to accept card for payment

Quite often there are situations when at the entrance to a merchant there is a sticker indicating that you can pay with a card, but at the time of payment it suddenly turns out that the cashier or seller does not want to accept the card for payment without explaining the reasons for the refusal. Such actions are a serious violation of the IPS rules and can entail the imposition of quite significant financial sanctions on the acquiring bank, which in turn can transmit them later to the merchant, if this is provided for by the terms of the agreement between them.

Requiring a passport when paying by card

The IPS rules clearly state that when making a payment by card, the seller does not have the right to request from the client (card bearer) data confirming the latter’s identity or other personal data, except in cases where this is necessary to complete the transaction (for example, indicating the customer’s residential address for the purpose of subsequent delivery of the goods) or when this is clearly stated in the requirements of local legislation. The seller has no authority to require the client to present a passport or other identification documents. As a striking example, we can cite the following situation: imagine that a client from China or a citizen of another country, exotic for us, who does not speak either Russian or English, pays with a card at a Russian retail outlet. In this case, the seller and buyer will not be able to communicate at all (of course, if the seller is not a polyglot). From the point of view of the rules of the Ministry of Railways, this practice of requiring documents when paying by card is punishable (a fine may be imposed on the acquiring bank with all the ensuing consequences for the merchant). However, some types of transactions (which primarily include cash withdrawal operations in bank offices and branches) must be performed only if the client presents an identification document.

Requirement to enter a PIN when paying with a card with a magnetic stripe

Today, more and more banks are issuing cards equipped not only with a magnetic stripe, but also with a microprocessor (chip). Such cards are called hybrid, and they can be used to make transactions using either a magnetic stripe or a chip. This is an undoubted advantage, since it is believed that the chip cannot be made at home, which, in turn, deprives fraudsters of the opportunity to make a counterfeit card by issuing a duplicate of it with a copy of the magnetic stripe track (so-called skimming). But often there is a situation when the merchant merchant, having read the card data from the magnetic stripe (not from the chip), asks the client to confirm his consent to make the payment by entering a PIN. This is completely unacceptable, as it carries the risk of complete compromise of the card data (i.e. magnetic stripe track/track and PIN), which could theoretically lead to the loss of all funds from the card account. Sellers explain their actions by saying that “the electronic terminal is programmed this way,” but most often the error lies in their actions: when working with electronic devices, they mistakenly indicate that the card type is not MasterCard, but Cirrus/Maestro. It is noteworthy that on the territory of the Russian Federation all transactions using Cirrus/Maestro cards must be carried out exactly as PBT!
Interesting fact: the Visa IPS rules state that in any case, when making a payment transaction for goods or services at a merchant, the client has the right to demand an SBT transaction. And this has a completely reasonable explanation: not all clients remember their PIN and some banks generally issue cards without a PIN for them. Of course, all of the above applies to cards with a magnetic stripe. For cards with a chip, the vast majority of transactions in merchants are confirmed by the client by entering a PIN.

Recently, MasterCard IPS issued a circular (operational bulletin) in which it notified all payment participants that from June 8, 2012, in the Russian Federation it is allowed to request a PIN to confirm by clients transactions with magnetic stripe cards carried out at merchants.

Thus, at present, on the territory of the Russian Federation, when registering transactions at merchants using cards with an MPS Visa magnetic stripe, entering a PIN is prohibited, but for cards with a MasterCard magnetic stripe, it is allowed. For cards with a microprocessor (so-called chip), entering a PIN is almost mandatory for both MPS.

Refusal to accept cards without the holder's name

To quickly enter the market, many issuers use so-called non-personalized, non-personalized cards, on the front side of which there is only a number and expiration date, but no last name and first name of the client (and this data, accordingly, is also absent on the first track of the magnetic stripe). The IPS rules clearly state that such cards are an absolutely legitimate means of payment and should be accepted on an equal basis with all other IPS products. Acquirers also specifically stipulate this point in their instructions for sellers, and yet, quite often, unfortunately, it happens that sellers flatly refuse to accept such cards for payment. As arguments, sellers argue that they have nothing to compare the client’s last and first name with (bearing in mind the prohibited practice of requesting supporting documents, which was discussed above). Such actions by TSP employees also contradict world practice and are subject to elaboration on the part of acquiring banks.

Increase in price (surcharge) for goods when paying by card

As is known, when concluding an acquiring agreement with a merchant, the bank indicates the amount of the so-called acquirer concession (commission), which will be charged (underpaid) to the merchant for all card transactions. This commission varies by country and type of activity of the merchant, taking into account the latter’s turnover. As a guide, you can keep in mind a value of the order of 1.5 - 2.5%. Thus, if the transaction amount is 1000 rubles, the acquiring bank will credit the current account with the amount minus this commission, that is, 975 - 985 rubles. The difference is the most important component of the acquirer’s activities and will be charged to operating income. This is a completely normal practice, generally accepted throughout the world, and the opinion that it is unprofitable for merchants is nothing more than a misconception: when paying in cash, other overhead costs arise that are quite comparable to these “losses” for acquiring. This includes the costs of merchants for cash conversion, their safe storage, collection, etc. Nevertheless, many merchants practice setting surcharges when paying for goods and services with cards, and the size of such “markups” is approximately equal to the size of the acquiring commission. This practice is completely unacceptable, which is clearly stated in the rules of the Ministry of Railways. The same rules of the Ministry of Railways provide a kind of loophole for merchants, namely: it states that merchants have the right to provide a discount for paying in cash. That is, in general, the price of a product or service when paying by card should not exceed the usual one, but you can give a discount to the client if he pays in cash.

Refusal to accept an unsigned card for payment

According to the rules of the Ministry of Railways, a special strip must be placed on the back of the card, intended for a sample signature of the legal card holder. When completing a payment transaction for goods or services at a merchant, the cashier must invite the buyer to confirm his willingness to pay for the transaction by either entering a PIN or signing a receipt from an electronic terminal. If consent is confirmed by signature, the cashier should compare the signature on the check with the sample signature on the back of the card. However, quite often, when receiving a card, the client does not put his signature (which is a violation of the IPS requirements and carries an increased risk of illegal use of the card by fraudsters if it is lost). Merchant merchants, seeing that a client is offering them an unsigned card, often refuse to accept such a means of payment, which is also unacceptable. According to the rules of the Ministry of Railways, in such cases the cashier should invite the buyer to present an identification document containing a photograph and a sample signature, then offer to sign the card, compare the signature on the card with the sample in the document and then complete the transaction in the usual way. If the buyer refuses to present a passport and (or) sign the card, the transaction should not be completed.

Setting the minimum purchase price/product for payment by card

There are often situations when a store arbitrarily sets a minimum amount, starting from which the seller agrees to accept the card for payment. For example, the purchase amount when paying by card should not be less than 100 rubles. (or 1000, 10,000, etc.). This practice is categorically unacceptable, since according to the rules of the Ministry of Railways, the terms of payment by card must fully comply with the terms of payment in cash.

Procedure for returning goods and spent funds

It happens that for some reason the client wants to return the purchased product back. If the goods were paid for using a card, then the money should be returned to the card account, and not in cash. Moreover, the refund must be made to the account of the exact card on which the initial payment was made. If the goods are returned, the merchant employee must complete the corresponding operation on the electronic terminal (refund/credit - return/credit). As a result of this operation, a credit receipt is printed on the terminal, which is confirmation and basis for the return of funds to the payer’s account. According to the rules of the Ministry of Railways, refunds must be made within 30 days from the date of execution of the credit transaction. If there is no receipt of funds to the card account after this period, the client can file a claim with the issuing bank, and cash will be returned based on the results of the claims cycle on the basis of “the loan has not been processed.”

Issuing receipts for card transactions

IPS have very strict requirements for the contents of electronic terminal receipts printed upon completion of the transaction. So, the following information must be indicated on the check:

description/price of each paid product/service;
date and time of operation;
transaction amount and currency;
card number (for security reasons, only the last four digits);
country, city, address of the location of the point or bank branch;
the name of the TSP or DBA (doing business as, DBA name, for example, VimpelCom OJSC is known on the market as Beeline);
authorization code (if any);
type of transaction (payment for goods, return);
space for the client's signature;
space for the initials of the seller, cashier or other identifier (for example, department number in a supermarket) of the department that serviced the card;
space for the seller’s signature (in case of a credit transaction);
the buyer's copy must contain text in Russian or English language approximately as follows: “Important: save this check to control transactions in the statement”;
other parameters in accordance with the requirements of local laws.

According to the requirements of the Bank of Russia, on checks of Russian merchants it is necessary to place a text about the amount of commission (usually they write “There is no acquirer commission”) charged to the buyer.

You also need to have text approximately as follows: “I hereby authorize my issuing bank to pay for this purchase and undertake to reimburse the issuer for the amount indicated in the “Total” column, plus all applicable fees.”

Customers must keep copies of receipts for at least six months to ensure they can verify the correct debits on their card transaction statements. The main purpose of the information on the check is to provide the ability to unambiguously correlate the information reflected in the statement with the data on the check. If the data on the check and the statement differ significantly, the client has the right to file a claim with all the ensuing dire consequences for the acquirer.

Filing claims based on detected violations

In all cases described in this article, affected customers - bank card holders need to contact only their issuing bank that issued the card. In this case, it will be necessary to provide the bank with such data as the exact address of the merchant, name, date, time, identifier or name of the acquiring bank (if the card transaction did not take place at all, i.e. the authorization request was not generated and did not go online , the issuer will not be able to determine this data independently), and the essence of the complaint (refusal to accept the card, requirement to present a passport, enter a PIN, etc.).

Obviously, there is no point in even trying to contact the acquiring bank, since in general, a situation with a violation of the rules for processing card transactions can take place anywhere in the world and the victim will not always be able to find time to visit the right place and is unlikely to have special knowledge and master terminology in the local dialect.

Based on such a request, the issuer has every right to send, in turn, a claim to the authorized body of the Ministry of Railways, and various sanctions can be applied to the acquirer - ranging from a warning and a requirement to conduct additional training for employees of the offending merchant network, up to the imposition of significant financial fines (hundreds and thousands of dollars or euros depending on the tariffs of the Ministry of Railways).

In our dynamic age, when non-cash payments are rapidly invading all areas of life, and transactions with bank cards have become an everyday occurrence, the aspect of customer literacy is very important. This question includes both the basics of the correct use of cards in everyday situations, and the nuances highlighted in this article, namely: what rights does the buyer have when paying for goods or services in a network of trade and service enterprises using a card and what exactly needs to be done in the event identifying violations of procedures for processing such transactions.

Since international payment systems work not with end clients (cardholders and merchants), but with financial institutions and primarily ensure that their products (cards) are accepted everywhere and without restrictions, acquirers are subject to very stringent requirements in terms of warranty and compliance with the procedures for accepting MPS cards in the network of their merchants. In cases of violations of the procedures and conditions for accepting cards, holders should complain to the issuing banks, which in turn have the right and obligation to inform the relevant MPS about such incidents, which ultimately can lead to very unpleasant sanctions for acquirers and incorrectly operating merchants and their employees.

September 2012

Trade and service companies

The use of Internet solutions CyberPlat® (“CyberPlat”) has a number of significant advantages for trading companies, namely: convenience and simplicity of the interface, minimal document flow, speed of settlements and optimization of costs for accepting payments at retail and service points. The proposed technology for making settlements for accepting payments works exclusively in real time - the payer deposits funds into the cash desk of the trade and service enterprise and the current account of the service provider company and the payer’s personal account in the provider’s billing system are instantly replenished.

Announcement

Any organization that provides services to the public can act as a service provider ( mobile operators, housing and communal services, electricity generating companies, digital and cable television operators, Internet providers, satellite signaling systems and others) - currently there are almost 4,700 of them.

To get started, you need to open a current account for a trade and service company in CB Platina and maintain a certain working balance on the account, within which payments are accepted. At the time of the transaction to accept payment, the client’s personal account is replenished online, and the funds are debited from the current account in CB Platina and transferred to the operator’s account.

A significant achievement of the CyberPlat® electronic payment system is the ability to choose a payment method and use various devices to process the payment depending on the capabilities of the dealers.

Payment can be made through the cashier:

(for example, a dealer company) using a computer connected to the Internet (or even a smartphone) and making a payment through the CyberPlat® system website ("CyberPlat")
using an automated cash register (for example, in a retail store) - in this case, interaction with the CyberPlat® electronic payment system is carried out through the retailer's server
application of 1C Enterprise technology
POS terminals
any phones and smartphones supporting Android, IOS, Java
other hardware.

and without human intervention:

payment terminals (cash-in)
ATMs

For example,

POS terminals are used for retail chains;
for the Eldorado network – special technology using the company's internal network;
large dealer networks (Svyaznoy, Euroset, Know-How, retail network MTS, Tele2 and others) use a solution based on a web interface;
small dealers and subdealers use “light” versions of the client part software, capable of working also via GPRS.

The CyberPlat® system keeps detailed records of all transactions when using any of the listed mechanisms, and complete payment statistics are available online to the dealer administrator on the company’s website

What is mcc code

MCC code — Merchant Category Code- a four-digit code reflecting the affiliation of a trade and service enterprise with a specific type of activity.

A specific MCC code is assigned to the seller by the bank servicing the payment terminal (acquiring bank) at the time of installation of the terminal. If the outlet is engaged in several types of activities, then mcc code assigned as main activity code(according to OKVED).

For different payment systems (Visa, Mastercard, MIR, etc.), specific codes for one type of activity may differ, but in general they correspond to the following ranges:

0001 - 1499 - agricultural sector;
1500 - 2999 - contract services;
3000 - 3299 - airline services;
3300 - 3499 - car rental;
3500 - 3999 - rental housing;
4000 - 4799 - transport services;
4800 - 4999 - utilities, telecommunications services;
5000 - 5599 - trade;
5600 - 5699 - clothing stores;
5700 - 7299 - other stores;
7300 - 7999 - business services;
8000 - 8999 - professional services and membership organizations;
9000 - 9999 - government services

Why do you need an mcc code?

Banks use MCC codes to generate statistics, analyze customer behavior, and to calculate cashback and bonuses according to loyalty programs.

Why do we, intelligent buyers, need this code? - For determining whether a retail outlet belongs to one or another category of retail outlets and to commit shopping with maximum benefit, using bank card with maximum cashback in the corresponding category.

How to find out the MCC code of a specific store

Before making a major purchase that offers a large cashback on one of your cards, it would be a good idea to make sure in advance that this purchase is definitely bonused (rewarded) by the Bank.

To do this you need in advance (even before paying for the purchase) find out the MCC code of the merchant. The following options are available:

1. MCC code - what is it, why is it needed, how to find out the category of retail outlets and what does cashback have to do with it

Directory of mcc codes

The easiest way is to contact mcc code directory(For example, mcc-codes.ru), and, using a search by name and city, find the point of interest and its MSS. It should be noted that the directory contains mainly chain and large stores, and perhaps mcc code of an unpopular or local outlet can't be found.

2. Flagon card and test (small) purchase

You can find out the mcc code by making a small purchase using flagometer cards(cards that display MCC codes for completed transactions in the Internet bank). To such marker cards include:

3. Incomplete (unpaid) purchase with a marker card

In order to find out mcc code this way, we need any card Bank Avangard. Determine mcc-code the desired point of sale as follows:

Make sure the card balance is zero (or there is a clear lack of funds on the card for a test, “false purchase”)
Select "product of interest" in the store
Make an unsuccessful attempt to pay for the "purchase"
After this, both in Internet banking and in mobile application an unsuccessful payment transaction will be reflected indicating MCC code of the trading terminal.

After this, you will be able to select the most profitable card for purchase using this mcc.

Don't forget to check out our list debit cards with cashback and interest for the remainder, he will help you choose the best card option. Also read: TOP debit cards with cashback at gas stations.

What is mcc code

MCC code - Merchant Category Code- a four-digit code reflecting the affiliation of a trade and service enterprise with a specific type of activity.

For different payment systems (Visa, Mastercard, MIR, etc.), specific codes for one type of activity may differ, but in general they correspond to the following ranges:

0001 - 1499 - agricultural sector;

1500 - 2999 - contract services;

3000 - 3299 - airline services;

3300 - 3499 - car rental;

3500 - 3999 - rental housing;

4000 - 4799 - transport services;

4800 - 4999 - utilities, telecommunications services;

5000 - 5599 - trade;

5600 - 5699 - clothing stores;

5700 - 7299 - other stores;

7300 - 7999 - business services;

8000 - 8999 - professional services and membership organizations;

9000 - 9999 - government services

Why do you need an mcc code?

Banks use MCC codes to generate statistics, analyze customer behavior, and to calculate cashback and bonuses according to loyalty programs.

Why do we, intelligent buyers, need this code? - For determining whether a retail outlet belongs to one or another category of retail outlets and to commit shopping with maximum benefit, using a bank card with maximum cashback in the corresponding category.

How to find out the MCC code of a specific store

Before making a major purchase that offers a large cashback on one of your cards, it would be a good idea to make sure in advance that this purchase is definitely bonused (rewarded) by the Bank.

To do this you need in advance (even before paying for the purchase) find out the MCC code of the merchant. The following options are available:

1. Directory of mcc codes

2. Flagon card and test (small) purchase

You can find out the mcc code by making a small purchase using flagometer cards(cards that display MCC codes for completed transactions in the Internet bank). To such marker cards include:

Avangard Bank cards
Yandex-Money card
iMoneyBank cards
MTS Bank cards

3. Incomplete (unpaid) purchase with a marker card

In order to find out mcc code this way, we need any card Bank Avangard. Determine mcc-code the desired point of sale as follows:

Make sure the card balance is zero (or there is a clear lack of funds on the card for a test, “false purchase”)
Select "product of interest" in the store
Make an unsuccessful attempt to pay for the "purchase"
After this, the unsuccessful payment transaction will be reflected both in the Internet bank and in the mobile application, indicating MCC code of the trading terminal.

After this, you will be able to select the most profitable card for purchase using this mcc.

Transformers with natural air cooled the TSP, TSZP and TSZPS series are used in the power supply circuits of the converters of sections of metro traction substations, assembled using a three-phase bridge circuit.
Transformers of the TSP, TSZP and TSZPS types are manufactured to replace the previously produced dry-type transformers TSV and TSZV, and are their analogues, the differences are only in the symbol of three-phase transformers. The change in the symbol of power transformers is caused by the reduction regulatory documentation, including the symbol, in accordance with the requirements of GOST.
The insulation of the network windings of transformers TSP, TSZP and TSZPS is thermosetting type "Transterm". The active part of the TSP, TSZP and TSZPS is protected by a casing with doors and is installed on support trolleys with smooth adjustable rollers. The doors are equipped with electric locking. The transformers are equipped with a temperature control device. The valve windings are protected by blow-out fuses. The transformer provides cable connection to the network.

Decoding of transformers TSP, TSZP and TSZPS

TSZPS-H/10M(MN)U3:
T - three-phase;
SZ - natural air cooling in a protected
execution;
P - for power supply of semiconductor converters;
C - own needs;
X - power consumption, kVA;
10 - voltage class of the HV network winding, kV;
M or MN - for metro substations with normal or
increased load capacity; U3 - climatic version and placement category.

Technical characteristics of TSP, TSZP, TSZPS *

Type	Nominal power, kVA	Rated voltage of windings, V		Weight, kg	Length x width x height, mm
Type	Nominal power, kVA	network winding, connected in D	valve winding, connected in U	Weight, kg	Length x width x height, mm
TSP-10/0.7-UHL4 (04)	7,3	380; 400; 500; 660	205	85	625 x 305 x 325
TSP-16/0.7-UHL4 (04)	14,6	380; 400; 500; 660	410	120	625 x 305 x 395
TSP-16/0.7-UHL4 (04)	14,6	380; 400; 500; 660	205	120	625 x 305 x 395
TSP-25/0.7-UHL4 (04)	29,1	380; 400; 500; 660	410; 205	160	645 x 355 x 515
TSP-25/0.7-UHL4 (04)	32,7	380	230	160	645 x 355 x 515
TSP-63/0.7-UHL4 (04)	58,0	380; 400; 500; 660	410	270	745 x 405 x 645
TSP-63/0.7-UHL4 (04)	58,0	380; 400; 500; 660	205	270	745 x 405 x 645
TSP-100/0.7-UHL4 (04)	93	380; 400; 660	205	405	865 x 405 x 680
TSP-125/0.7-UHL4 (04)	117	380; 400; 660	410	450	865 x 405 x 730
TSZP-10/0.7-UHL4 (04)	7,3	380; 400; 500; 660	205	100	665 x 400 x 360
TSZP-16/0.7-UHL4 (04)	14,6	380; 400; 500; 660	410	135	665 x 400 x 430
TSZP-16/0.7-UHL4 (04)	14,6	380; 400; 500; 660	205	135	665 x 400 x 430
TSZP-25/0.7-UHL4 (04)	29,1	380; 400; 500; 660	410	175	685 x 410 x 550
TSZP-25/0.7-UHL4 (04)	29,1	380; 400; 500; 660	205	175	685 x 410 x 550
TSZP-25/0.7-UHL4 )**	29,1	380	102,5-60	185	685 x 410 x 550
TSZPS-25/0.7-UHL4	29,1	380	230	185	685 x 410 x 550
TSZP-63/0.7-UHL4 (04)	58,0	380; 400; 500; 660	410; 205	290	790 x 450 x 690
TSZP-63/0.7-UHL4 (04)	65,3	380	230	290	790 x 450 x 690
TSZPS-63/0.7-UHL4	48	380	230	290	790 x 450 x 690
TSZP-100/0.7-UHL4 (04)	93 104,37	380; 400; 660 380	205 230	430	910 x 490 x 730
TSZPS-100/0.7-UHL4	75	380	230	430	910 x 490 x 730
TSZP-125/0.7-UHL4 (04)	117	380; 400; 660	410	480	910 x 490 x 780

*) The transformer windings are connected into a circuit and connection group D/U-11. Transformers of the TSZPS type have a circuit and connection group Un/Un-0.
For transformers of the TSP and TSZP types, by agreement of the parties, versions for voltages of 380/230 V are possible.
Transformers in tropical design (04) are produced with a rated mains winding voltage of 380, 400, 415, 440 V.
The heat resistance class of insulation for temperate climates is “F”, for tropical climates - “N” according to GOST 8865-87.

If really, really in simple language, this is the postal service.

Each member of an IP-compatible network has its own address, which looks something like this: 162.123.058.209. The total number of such addresses for the IPv4 protocol is 4.22 billion.

Let's assume that one computer wants to contact another and send it a message - a "packet". He will contact the TCP/IP "postal service" and give it his package, indicating the address to which it needs to be delivered. Unlike addresses in the real world, the same IP addresses are often assigned to different computers in turn, which means the “postman” does not know where he is physically located the right computer, so he sends the parcel to the nearest "post office" - to network card computer. Perhaps there is information there about where the desired computer is located, or perhaps such information is not there. If it is not there, an address request is sent to all nearby “post offices” (switchboards). This step is repeated by all "post offices" until they find the desired address, while they remember how many "post offices" this request has passed before them and if it passes a certain (large enough) number of them, then it will be returned back with the mark " address not found." The first "post office" will soon receive a bunch of responses from other "branches" with options for routes to the addressee. If no short enough path is found (usually 64 shipments, but no more than 255), the package will be returned to the sender. If one or more paths are found, the package will be transmitted along the shortest of them, while the “post offices” will remember this path for a while, allowing subsequent packages to be quickly transmitted without asking anyone for the address. After delivery, the “postman” will definitely force the recipient to sign a “receipt” stating that he received the parcel and give this “receipt” to the sender as evidence that the parcel was delivered intact - verification of delivery in TCP is mandatory. If the sender does not receive such a receipt after a certain period of time, or the receipt states that the package was damaged or lost during shipment, then he will try to send the package again.

The protocol stack, or colloquially TCP/IP is called network architecture modern devices, designed for use on the network. A stack is a wall in which each component brick lies on top of the other and depends on it. The protocol stack began to be called the “TCP/IP stack” thanks to the two main protocols that were implemented - IP itself, and TCP based on it. However, they are only the main and most common ones. If not hundreds, then dozens of others are still used today for various purposes.

The world wide web we are familiar with is based on the HTTP (hyper-text transfer protocol), which in turn operates on TCP. This is a classic example of using a protocol stack. There are also protocols Email IMAP/POP and SMTP, remote shell protocols SSH, remote desktop RDP, MySQL databases, SSL/TLS, and thousands of other applications with their own protocols (..)

How are all these protocols different? It's quite simple. In addition to the various objectives set during development (for example, speed, safety, stability and other criteria), protocols are created for the purpose of differentiation. For example, there are application level protocols that are different for different applications: IRC, Skype, ICQ, Telegram and Jabber are incompatible with each other. They are designed to perform a specific task, and in this case the ability to make WhatsApp calls in ICQ is simply not technically defined, since the applications use a different protocol. But their protocols are based on the same IP protocol.

A protocol can be called a planned, standard sequence of actions in a process in which there are several subjects; on the network they are called peers (partners), less often - a client and a server, emphasizing the features of a specific protocol. The simplest example of protocol for those who still do not understand is a handshake at a meeting. Both know how and when, but the question why is a question for the developers, not the users of the protocol. By the way, a handshake is available for almost all protocols, for example, to ensure separation of protocols and protection against “flying on the wrong plane.”

Here's what TCP/IP is using the most popular protocols as an example. This shows the dependency hierarchy. It must be said that applications only use the specified protocols, which may or may not be implemented within the OS.

TCP/IP is a set of protocols.

Protocol is a rule. For example, when someone greets you, you say hello back (rather than saying goodbye or wishing you happiness). Programmers will say that we use the hello protocol, for example.

What kind of TCP/IP (now it will be very simple, don’t let your colleagues get bombed):

Information reaches your computer via wires (radio or whatever else is not important). If current is passed through the wires, it means 1. If it is turned off, it means 0. It turns out 10101010110000 and so on. 8 zeros and ones (bits) is a byte. For example 00001111. This can be represented as a number in binary. In decimal form, a byte is a number from 0 to 255. These numbers are mapped to letters. For example, 0 is A, 1 is B. (This is called encoding).

So. In order for two computers to effectively transmit information over wires, they must supply current according to some rules - protocols. For example, they must agree on how often the current can be changed so that they can distinguish a 0 from a second 0.

This is the first protocol.

Computers somehow understand that one of them has stopped giving information (like “I said everything”). To do this, at the beginning of the data sequence 010100101, computers can send a few bits, the length of the message they want to transmit. For example, the first 8 bits could indicate the length of the message. That is, first the encoded number 100 is transmitted in the first 8 bits and then 100 bytes. The receiving computer will then wait for the next 8 bits and the next message.

Here we have another protocol, with its help you can transmit messages (computer ones).

There are a lot of computers, so they can understand who needs to send a message. unique addresses computers and a protocol that allows you to understand to whom this message is addressed. For example, the first 8 bits will indicate the recipient's address, the next 8 will indicate the length of the message. And then the message. We just stuck one protocol inside another. The IP protocol is responsible for addressing.

Communication is not always reliable. For reliable delivery of (computer) messages, TCP is used. When executing the TCP protocol, computers will ask each other whether they received the correct message. There is also UDP - this is when computers do not ask whether they received it. Why is it necessary? Here you are listening to Internet radio. If a couple of bytes arrive with errors, you will hear, for example, “psh” and then music again. Not fatal, and not particularly important - UDP is used for this. But if a couple of bytes get corrupted when loading the site, you’ll get crap on your monitor and won’t understand anything. The site uses TCP.

TCP/IP (UDP/IP) are nested protocols on which the Internet operates. Ultimately, these protocols make it possible to transmit a computer message intact and precisely to the address.

There is also the http protocol. The first line is the site address, the subsequent lines are the text that you send to the site. All http lines are text. Which is shoved into TCP message, which is addressed using IP and so on.

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