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 might be the relevance of the relevant standards?
What are communication protocols?
A communication protocol is a list of unified instructions that establish how certain software or hardware interfaces should provide data transfer - for example, text, graphic, audio and video streams. Corresponding protocols are created mainly to facilitate the scaling of various computer networks. For example, the introduction of the TCP / IP protocol made it possible to unify data transfer virtually throughout the world, making it possible to integrate 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 refined, updated. New protocols are periodically developed that reflect the specifics of the development of the communication market. Various communication protocols can be used in both domestic and industrial networks, implemented on the basis of the infrastructure of research centers, etc. Among the most common standards of the corresponding type are Ethernet, CAN, HART.
The use of communication protocols is also carried out in the field of mobile communications services. Among them - 3G, 4G, GPRS.
These protocols in the networks of mobile operators differ, in particular:
- by the speed of data transfer between the subscriber and the communication service provider;
- by frequency ranges;
- 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. Consider its specifics in more detail.
Classification of computer communication protocols
The classification of relevant protocols can be carried out using a sufficiently large number of approaches. It is common that telecommunication standards can be subdivided into lower and higher levels. Among those:
- applied;
- representative;
- session;
- transport;
- network;
- channel;
- physical.
We will study them in more detail.
Network layer application layer
The level under consideration, in the framework of which a particular communication protocol can be classified, relates primarily to applications. That is, it provides communication between the network infrastructure and specific user programs. It uses such protocols as HTTP, Telnet, DNS, IRC, BitTorrent and many others, through which the delivery of modern online services is carried out.
Executive Network Protocol
At an appropriate level, the communication protocol involves the presentation of certain data. Here, the procedures for converting one protocol to another, encoding, file compression, and managing various requests can be implemented.
Specific applications set certain requests to the network, after which they are converted into a language that the server understands. Next, 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 some extent to those of HTTP and FTP.
Session layer communication protocols
At this level, the communication protocol is used to implement 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 are ASP, DLC, SOCKS.
Transport layer of communication protocols
Corresponding type of standards are used to directly deliver certain types of data from one network object to another. In many cases, there is a division of files into separate elements - to facilitate their transfer. Protocols of the corresponding type include TCP, UDP, RMTP.
Network layer protocols
The next type of standards on the basis of which a communication system can function is network layer protocols. They are responsible, first of all, for data transmission methods, address translation, switching, monitoring the quality of infrastructure work. Such protocols include, in particular, the same TCP / IP, ICMP. DHCP
Link layer protocols
These standards are applied to ensure the functioning of key network hardware components. Corresponding protocols allow the system, first of all, to check the data coming from the physical layer for errors. If necessary, their adjustment is also carried out. Among such standards - the common communication protocol PPP, algorithms such as SLIP, L2F, PROFIBUS. In principle, Ethernet can also be referred to as channel protocols.
Protocol Physical Layer
The next level of validity of the standards in question is physical. Here, the communication protocol is a tool through which the digital data stream is transmitted 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 can be used. Common wireless protocols - in particular, implemented using Wi-Fi routers - are those that are of type IEEE 802.11.
The classification of standards we have studied can be considered very conditional. So, within the framework of it, it can be very problematic to attribute a particular protocol to a specific category: it often happens that the standard is applied at once at several levels. It will be useful to consider in more detail the specifics of the protocols most popular in the modern information technology market. Such as, for example, the PPP control protocol (communication - it is it that is the subject of the influence of the algorithms that are provided for by the corresponding standard).
What is PPP?
The protocol under consideration refers, as we noted above, to standards that are designed to ensure the functioning of network infrastructure at the data link layer. It is universal: through the appropriate protocol, you can implement device authentication, use the data encryption mechanism, and if necessary, file compression.
The protocol under consideration ensures the functioning of networks based on common communication resources - such as telephone lines, cellular communication channels. If an inscription pops up in a program stating that the PPP connection was interrupted, then this will most likely mean that the user cannot get actual access to network resources, which are provided by his provider.
There are several varieties of the corresponding standard - for example, PPPoE, PPPoA. Moreover, the protocol structure in question includes several standards: LCP, NCP, PAP, CHAP, MLPPP. Another protocol common in today's IT market is HTTP.
What is the HTTP protocol?
The corresponding standard is used to ensure the operation of the infrastructure for the exchange of hypertext data - in the general case between computers and servers on the Internet. Refers to the fundamental protocols that support the World Wide Web. By default, it is supported by most modern communication software tools in common operating systems. It is distinguished by stability - it is difficult to imagine a situation in which an HTTP program message pops up on the user’s screen like “the PPP connection protocol was interrupted”. In the extreme case, if for some reason the tools for using the HTTP standard are not available, you can use, for example, the FTP protocol to transfer files online, although in many cases its use may not be the best solution.
The standard in question involves the transfer of data from a hardware-software object in the status of a client to a server and vice versa. The first sends requests to the second, and he answers 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;
- the possibility of expansion;
- the availability of broad support from software manufacturers.
He also has a number of shortcomings highlighted by experts:
- a sufficiently large value of individual messages;
- inability to distributed computing;
- lack of ability to navigate through resources hosted on the server.
We noted above that the communication standard under consideration is supported by the main user operating systems, as well as by common software products. However, the scope of this protocol is much wider than the implementation of communication algorithms within user solutions. The HTTP standard is applicable in industry, video surveillance systems, in the SCADA infrastructure.
A large number of manufacturers, considering various communication protocols in networks as basic for building a communication infrastructure, choose HTTP - as a functional and reliable tool for organizing access to various online resources, configuring objects, and managing various devices.
Speaking specifically about the industry, Modbus is one of the most popular protocols in the corresponding market segment.
What is the Modbus protocol?
The relevant standard is mainly used to ensure the interaction between the various elements within the framework of the automation infrastructure in the workplace. The corresponding protocol can be presented in those varieties that are adapted to transmit data on a specific type of communication channel - wired, wireless (in turn, the resources of the first type may include copper, fiber-optic cables - and they have developed separate modifications of the protocol about which speech).
There are versions of Mobdus adapted for transferring data over TCP / IP. Another popular solution among industrial enterprises is PROFIBUS-FDL.
What is the PROFIBUS-FDL protocol?
The protocol under consideration operates within the framework of the PROFIBUS network, which has become widespread among European industrial enterprises. Its prototype was developed by Siemens specialists and was to be used at production sites where controllers were involved.
Subsequently, based on the development of the German corporation, a network infrastructure was formed in which various technological as well as functional features of serial communications related to the field level were combined. The network protocol under consideration allowed the integration of heterogeneous automation devices within a single production system. It is worth noting that the PROFIBUS-FDL protocol is not the only one that operates on the specified industrial network. However, it is uniform in terms of applicability in order to organize access to the main bus.
One way or another, the communication protocol in question is supplemented by the following standards:
- DP;
- PA;
- FMS.
The PROFIBUS DP protocol is used to organize data exchange between leading industrial devices of the DP type, as well as devices on which I / O is implemented according to a distributed scheme. Moreover, 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 enables data exchange between infrastructure, which consists of field-level equipment. This protocol is optimized for connecting various sensors and mechanisms to a common linear or ring bus.
The PROFIBUS FMS standard is universal. It is intended primarily for organizing the exchange of data between high-tech components of industrial infrastructure - computers, programmers, controllers.
Among the strengths of the protocols operating on the PROFIBUS network are openness (that is, they can be used by any interested industrial enterprises), widespread use (which leads to easier scaling of the industrial infrastructure while expanding markets, opening new industries).
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 transfer within the framework of unified formats. That is - those that can be scaled within the framework of the infrastructure, as a rule, significantly exceeding the scale of a single enterprise.
In fact, we are talking about international standards: modern protocols for cellular communications, wired, Wi-Fi-communications, are very widespread, public, relatively easy to scale. Of course, in some cases, even in such global markets as the provision of cellular communication services, regional protocols are possible, but in the interests of the largest brands - to introduce, if this does not contradict the interests of business, and in some cases the state, as much as possible unified standards, which will enhance international communications.
There are a number of fundamental communication protocols. In the context of the Internet, these include HTTP, TCP / IP. In the segment of network access services, the PPP standard can be classified as such. If a user sees a message stating that the PPP control protocol has been interrupted, then he will most likely not be able to access online resources using either HTTP or TCP / IP. Thus, each standard is of great importance and, moreover, in many cases is inextricably linked with others. If one protocol is interrupted by communication, then it is likely that the user will not be able to access those resources for which other standards are responsible for organizing communications.
Communication protocols are an indispensable tool for solving complex problems both in the field of providing user communications and in industrial and service areas. The successful implementation of the corresponding infrastructure, as well as its effectiveness, in terms of the ratio of system performance and installation costs depends on the competent choice of a specific standard. Thus, an early study of the properties of network protocols, the choice of the optimal one is an important task for the enterprise managers responsible for the implementation and modernization of the company's communication infrastructure.