Communication protocol: data transmission

The functioning of both local and global computer networks, mobile and other communication services involves the use of various communication protocols. Which of them can be considered the most common? What could be the significance of the relevant standards?

What are the communication protocols?

A communications protocol is a list of unified instructions that establish how certain software or hardware interfaces should provide data transfer - for example, text, graphics, audio and video streams. The corresponding protocols are created mainly to facilitate the scaling of various computer networks. For example, the implementation of the TCP / IP protocol has made it possible to unify data transmission virtually all over the world, making it possible to combine computers into the global Internet.

In the modern market of information technologies, communication channel protocols are used at various levels of implementation of communication interfaces. They are constantly being updated, updated. Periodically, new protocols are developed that reflect the specifics of the development of the communication market. Various communication protocols can be used in networks for both domestic and industrial use, based on the infrastructure of research centers, etc. Among the most common standards of the appropriate type are Ethernet, CAN, HART.

The use of communication protocols is also carried out in the field of mobile communication services. Among them - 3G, 4G, GPRS.

These protocols in the networks of mobile operators are different, in particular:

- the speed of data transfer between the subscriber and the provider of communication services;

- by frequency bands;

- in terms of the maximum distance of the communication device to the base station.

As for the classification of computer communication protocols, it is characterized by a rather high level of complexity. Let us consider its specifics in more detail.

Classification of computer communication protocols

The classification of the relevant protocols can be carried out using a sufficiently large number of approaches. It is common that the standards of communication can be subdivided into lower and higher levels. Among them are:

- Applied;

- Representative;

- session;

- transport;

- Networking;

- channel;

- Physical.

Let's study them in more detail.

Applied level of network protocols

The considered level, within which a certain communication protocol can be classified, refers, first of all, to applications. That is, it provides communication between the network infrastructure and specific user programs. Here, protocols such as HTTP, Telnet, DNS, IRC, BitTorrent and many others are used, through which modern online services are delivered.

Representative level of network protocols

At the appropriate level, the communication protocol assumes the presentation of certain data. Here you can perform procedures for converting one protocol to another, encoding, compressing files, managing various queries.

Specific applications specify specific requests to the network, and then - they are converted into a language that is understandable to the server. Then the request is processed. Then the response from the server is converted, in turn, into a language that the application understands. Among the popular protocols of the corresponding type are ASN, FTP, SMTP. It can also be attributed to a certain extent to HTTP and FTP.

Session layer communication protocols

At this level, the communication protocol is used to perform a specific operation - for example, synchronizing certain tasks, creating a communication session, sending or receiving a file. Among the common protocols that are used for such purposes - ASP, DLC, SOCKS.

Transport layer of communication protocols

Appropriate type of standards are used to directly deliver certain types of data from one network object to another. In many cases, the files are divided into separate elements - to facilitate their transfer. The protocols of the appropriate type include TCP, UDP, RMTP.

Network protocol layer

The following type of standards, on the basis of which the communication system can operate - network layer protocols. They are responsible, first of all, for the methods of data transmission, address translation, switching, monitoring of the quality of the operation of the infrastructure. These protocols include, in particular, the same TCP / IP, ICMP. DHCP.

Link layer protocols

These standards are used to ensure the operation of key hardware components of the network. The corresponding protocols allow the system, first of all, to check the data coming from the physical layer for errors. If necessary, they are also adjusted. Among these standards are the widespread PPP communication protocol, algorithms such as SLIP, L2F, PROFIBUS. In principle, Ethernet can be referred to channel protocols.

Physical layer of protocols

The next level of action of the standards in question is physical. Here, the communication protocol is a tool through which the transmission of a digital data stream is carried out directly - by sending a signal through a cable or via a radio channel.

In the case of wired transmission, standards such as RS-232, xDSL, 100BASE-T may be used. Common wireless communication protocols - in particular, implemented using Wi-Fi routers - are those that are of the IEEE 802.11 type.

The classification of standards we have studied can be considered very conditional. So, within the framework of it, it can be very problematic to classify a particular protocol as a specific category: it often happens that the standard is applied immediately on several levels. It will be useful to consider in more detail the specifics of the most popular protocols on the modern IT market. Such as, for example, the PPP control protocol (a link - it is the object of the impact of algorithms that are provided by the corresponding standard).

What is the PPP protocol?

The protocol in question refers, as we noted above, to standards that are designed to support the operation of a network infrastructure at the data link layer. It is universal: by means of the appropriate protocol it is possible to implement device authentication, use the data encryption mechanism, and, if necessary, compress the files.

The protocol under consideration ensures the functioning of networks based on common communication resources - such as telephone lines, cellular channels. протокол PPP связью был прерван, то это, скорее всего, будет означать невозможность получения пользователем фактического доступа к сетевым ресурсам, что предоставляются его провайдером. If an inscription appears in a program that the PPP connection has been interrupted, this will most likely mean that the user can not actually access the network resources provided by his provider.

There are several versions of the corresponding standard - for example, PPPoE, PPPoA. At the same time, the protocol structure in question includes several standards: LCP, NCP, PAP, CHAP, MLPPP. Another protocol common in the modern IT market is HTTP.

What is the HTTP protocol?

The corresponding standard is used to ensure the operation of the hypertext exchange infrastructure - in general, between computers and servers on the Internet. Refers to the basic protocols that support the work of the World Wide Web. By default it is supported by the majority of modern software communication tools in common operating systems. It differs in stability - it is difficult to imagine a situation in which an HTTP-program message pops up on the user's screen like "PPP-connection was interrupted". In extreme cases - if for any reason the tools for using the HTTP standard are not available, you can use FTP, for example, to transfer files online, although in many cases its use may not be the most optimal solution.

The standard in question involves the transfer of data from the hardware and software object in the status of the client to the server and vice versa. The first sends the second request, and he responds to them according to the established algorithm. There are several varieties of the protocol under consideration: for example, HTTPS, HTTP-NG. The main advantages that determine the fact that the HTTP communication protocol has become one of the most popular:

- universality;

- ease of implementation;

- possibility of expansion;

- the availability of broad support from software vendors.

There are also a number of shortcomings, allocated by experts:

- a sufficiently large amount of individual messages;

- non-adaptability to distributed computing;

- the lack of the ability to navigate through resources hosted on the server.

Above we noted that the communication standard in question is supported by the basic user operating systems, as well as by the widespread software products. However, the scope of this protocol is much broader than the implementation of communication algorithms within user solutions. The HTTP standard is also applicable in industry, video surveillance systems, in the SCADA infrastructure.

A large number of manufacturers, considering various communication protocols in networks as the base for building a communication infrastructure, choose HTTP - as a functional and reliable tool for organizing access to various online resources, configuring objects, managing various devices.

Speaking specifically about the industry, Modbus is one of the most popular protocols in the relevant market segment.

What is the Modbus protocol?

The relevant standard is mainly used to ensure the interaction between various elements within the automation infrastructure in the workplace. The corresponding protocol can be presented in those versions that are adapted to the transmission of data on a specific type of communication channel - wireline, wireless (in turn, resources of the first type can include copper, fiber cables - and for them, some modifications of the protocol Speech).

There are versions of Mobdus, adapted for transferring data over TCP / IP. The solution is PROFIBUS-FDL, which is popular among industrial enterprises.

What is the PROFIBUS-FDL protocol?

The protocol under consideration functions within the PROFIBUS network, which has become widespread among European industrial enterprises. Its prototype was developed by Siemens specialists and was to be used in production areas where controllers were involved.

Subsequently, based on the developments of the German corporation, a network infrastructure was formed, in which various technological as well as functional features of the serial communications related to the field level were combined. The network protocol under consideration allowed the integration of various types of automation devices within a single production system. It should be noted that PROFIBUS-FDL protocol is not the only one that functions in the specified industrial network. However, it is uniform from the point of view of applicability in order to organize access to the main bus.

Anyway, the communication protocol under consideration is supplemented by the following standards:

- DP;

- PA;

- FMS.

The PROFIBUS DP protocol is used to organize the exchange of data between the leading industrial devices such as DP, as well as devices in which I / O is implemented in a distributed scheme. This protocol allows you to organize data exchange at high speed. It is also characterized by a relatively low cost of implementation, which can make it popular in small enterprises.

The PROFIBUS PA standard allows for the exchange of data between an infrastructure that consists of equipment related to the field level. This protocol is optimized for connecting different sensors and mechanisms to a common linear or ring bus.

The PROFIBUS FMS standard is versatile. It is intended, first of all, for the organization of data exchange between high-tech components of industrial infrastructure - computers, programmers, controllers.

Among the strongest aspects of the protocols functioning in the PROFIBUS network are openness (that is, they can be used by any interested industrial enterprises), a wide prevalence (which makes it easier to scale the industrial infrastructure while expanding markets, opening new production facilities).

Summary

So, we examined the essence of communication protocols, studied the features of some popular varieties of relevant standards. Their main purpose is to ensure data transmission within the framework of standardized formats. That is, those that can be scaled within the infrastructure, usually much larger than the scale of a single enterprise.

In fact, we are talking about international standards: modern protocols of cellular communication, wired, Wi-Fi communications, are widely distributed, widely available, relatively easy to scale. Certainly, in some cases, even in such global markets as the provision of cellular communication services, regional protocols can be used, but in the interests of the largest brands - to introduce, if it does not contradict the interests of business, and in some cases - states, as harmonized standards as possible, Which will make it possible to intensify international communications.

There are a number of fundamental communication protocols. In the context of the Internet, one can include HTTP, TCP / IP. In the segment of services to provide access to the network to such can be referred to the standard of PPP. If the user sees a message that the PPP link control protocol has been interrupted, he most likely will not be able to access online resources using either HTTP or using TCP / IP. Thus, each standard has great significance and, moreover, in many cases is inextricably linked with others. If one communication protocol is interrupted, then it is likely that the user will not be able to access those resources, for the organization of communications with which other standards meet.

Communication protocols are an indispensable tool for solving complex problems both in the field of providing user communications and in the industrial and service spheres. From the competent choice of a specific standard depends the success of the implementation of the relevant infrastructure, as well as its effectiveness - in terms of the ratio of system performance and the cost of its installation. Thus, the advance study of the properties of network protocols, the selection of the optimal one is an important task for enterprise managers responsible for the implementation and modernization of the company's communications infrastructure.