Standard Organization In Data Communication And Networking Pdf
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A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network. Essentially, it allows connected devices to communicate with each other, regardless of any differences in their internal processes, structure or design. Network protocols are the reason you can easily communicate with people all over the world, and thus play a critical role in modern digital communications. Neither local area networks LAN nor wide area networks WAN could function the way they do today without the use of network protocols. Network protocols take large-scale processes and break them down into small, specific tasks or functions.
A communication protocol is a system of rules that allow two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax , semantics and synchronization of communication and possible error recovery methods.
Protocols may be implemented by hardware , software , or a combination of both. Communicating systems use well-defined formats for exchanging various messages.
Each message has an exact meaning intended to elicit a response from a range of possible responses pre-determined for that particular situation. The specified behavior is typically independent of how it is to be implemented. Communication protocols have to be agreed upon by the parties involved. A programming language describes the same for computations, so there is a close analogy between protocols and programming languages: protocols are to communication what programming languages are to computations.
Multiple protocols often describe different aspects of a single communication. A group of protocols designed to work together is known as a protocol suite; when implemented in software they are a protocol stack.
Networking research in the early s by Robert E. TCP software was redesigned as a modular protocol stack. International work on a reference model for communication standards led to the OSI model , published in For a period in the late s and early s, engineers, organizations and nations became polarized over the issue of which standard , the OSI model or the Internet protocol suite, would result in the best and most robust computer networks.
The information exchanged between devices through a network or other media is governed by rules and conventions that can be set out in communication protocol specifications.
The nature of communication, the actual data exchanged and any state -dependent behaviors, is defined by these specifications. In digital computing systems, the rules can be expressed by algorithms and data structures.
Protocols are to communication what algorithms or programming languages are to computations. Operating systems usually contain a set of cooperating processes that manipulate shared data to communicate with each other.
This communication is governed by well-understood protocols, which can be embedded in the process code itself. Transmission is not necessarily reliable, and individual systems may use different hardware or operating systems. To implement a networking protocol, the protocol software modules are interfaced with a framework implemented on the machine's operating system. This framework implements the networking functionality of the operating system.
At the time the Internet was developed, abstraction layering had proven to be a successful design approach for both compiler and operating system design and, given the similarities between programming languages and communication protocols, the originally monolithic networking programs were decomposed into cooperating protocols. Systems typically do not use a single protocol to handle a transmission.
Instead they use a set of cooperating protocols, sometimes called a protocol suite. The protocols can be arranged based on functionality in groups, for instance, there is a group of transport protocols. The functionalities are mapped onto the layers, each layer solving a distinct class of problems relating to, for instance: application-, transport-, internet- and network interface-functions.
The selection of the next protocol is accomplished by extending the message with a protocol selector for each layer. Getting the data across a network is only part of the problem for a protocol. The data received has to be evaluated in the context of the progress of the conversation, so a protocol must include rules describing the context. These kind of rules are said to express the syntax of the communication.
Other rules determine whether the data is meaningful for the context in which the exchange takes place. These kind of rules are said to express the semantics of the communication. Messages are sent and received on communicating systems to establish communication. Protocols should therefore specify rules governing the transmission.
In general, much of the following should be addressed: . Systems engineering principles have been applied to create a set of common network protocol design principles.
The design of complex protocols often involves decomposition into simpler, cooperating protocols. Such a set of cooperating protocols is sometimes called a protocol family or a protocol suite,  within a conceptual framework. Communicating systems operate concurrently. An important aspect of concurrent programming is the synchronization of software for receiving and transmitting messages of communication in proper sequencing.
Concurrent programming has traditionally been a topic in operating systems theory texts. Mealy and Moore machines are in use as design tools in digital electronics systems encountered in the form of hardware used in telecommunication or electronic devices in general. The literature presents numerous analogies between computer communication and programming. In analogy, a transfer mechanism of a protocol is comparable to a central processing unit CPU.
The framework introduces rules that allow the programmer to design cooperating protocols independently of one another.
In modern protocol design, protocols are layered to form a protocol stack. Layering is a design principle that divides the protocol design task into smaller steps, each of which accomplishes a specific part, interacting with the other parts of the protocol only in a small number of well-defined ways. Layering allows the parts of a protocol to be designed and tested without a combinatorial explosion of cases, keeping each design relatively simple. The communication protocols in use on the Internet are designed to function in diverse and complex settings.
Internet protocols are designed for simplicity and modularity and fit into a coarse hierarchy of functional layers defined in the Internet Protocol Suite. The OSI model was developed internationally based on experience with networks that predated the internet as a reference model for general communication with much stricter rules of protocol interaction and rigorous layering.
Typically, application software is built upon a robust data transport layer. Underlying this transport layer is a datagram delivery and routing mechanism that is typically connectionless in the Internet. Packet relaying across networks happens over another layer that involves only network link technologies, which are often specific to certain physical layer technologies, such as Ethernet.
Layering provides opportunities to exchange technologies when needed, for example, protocols are often stacked in a tunneling arrangement to accommodate the connection of dissimilar networks. Protocol layering forms the basis of protocol design. Together, the layers make up a layering scheme or model. Computations deal with algorithms and data; Communication involves protocols and messages; So the analog of a data flow diagram is some kind of message flow diagram.
The systems, A and B, both make use of the same protocol suite. The vertical flows and protocols are in-system and the horizontal message flows and protocols are between systems. The message flows are governed by rules, and data formats specified by protocols.
The blue lines mark the boundaries of the horizontal protocol layers. The software supporting protocols has a layered organization and its relationship with protocol layering is shown in figure 5. To send a message on system A, the top-layer software module interacts with the module directly below it and hands over the message to be encapsulated. The lower module fills in the header data in accordance with the protocol it implements and interacts with the bottom module which sends the message over the communications channel to the bottom module of system B.
On the receiving system B the reverse happens, so ultimately the message gets delivered in its original form to the top module of system B. Program translation is divided into subproblems. As a result, the translation software is layered as well, allowing the software layers to be designed independently.
The modules below the application layer are generally considered part of the operating system. Passing data between these modules is much less expensive than passing data between an application program and the transport layer. The boundary between the application layer and the transport layer is called the operating system boundary. Strictly adhering to a layered model, a practice known as strict layering, is not always the best approach to networking.
While the use of protocol layering is today ubiquitous across the field of computer networking, it has been historically criticized by many researchers  for two principal reasons. Firstly, abstracting the protocol stack in this way may cause a higher layer to duplicate the functionality of a lower layer, a prime example being error recovery on both a per-link basis and an end-to-end basis.
The others address issues in either both areas or just the latter. Finite state machine models   and communicating finite-state machines  are used to formally describe the possible interactions of the protocol. For communication to occur, protocols have to be selected. The rules can be expressed by algorithms and data structures. Hardware and operating system independence is enhanced by expressing the algorithms in a portable programming language.
Source independence of the specification provides wider interoperability. Protocol standards are commonly created by obtaining the approval or support of a standards organization, which initiates the standardization process.
This activity is referred to as protocol development. The members of the standards organization agree to adhere to the work result on a voluntary basis. Often the members are in control of large market-shares relevant to the protocol and in many cases, standards are enforced by law or the government because they are thought to serve an important public interest, so getting approval can be very important for the protocol.
BSC is an early link-level protocol used to connect two separate nodes. It was originally not intended to be used in a multinode network, but doing so revealed several deficiencies of the protocol. In the absence of standardization, manufacturers and organizations felt free to 'enhance' the protocol, creating incompatible versions on their networks. In some cases, this was deliberately done to discourage users from using equipment from other manufacturers. There are more than 50 variants of the original bi-sync protocol.
One can assume, that a standard would have prevented at least some of this from happening. In some cases, protocols gain market dominance without going through a standardization process. Such protocols are referred to as de facto standards. De facto standards are common in emerging markets, niche markets, or markets that are monopolized or oligopolized.
They can hold a market in a very negative grip, especially when used to scare away competition. From a historical perspective, standardization should be seen as a measure to counteract the ill-effects of de facto standards.
Standardization is therefore not the only solution for open systems interconnection. The IEEE controls many software and hardware protocols in the electronics industry for commercial and consumer devices.
What Is a Network Protocol, and How Does It Work?
Data means information in digital format and communication means to exchange information between two or many users in anyways like speaking, texting, or any other modes of the medium. So, data communication is simply the exchange of data between two or many users through the transmission media like twisted pair cable, coaxial cable, optical fibers, radio wave, satellite microwave, etc. The user or device that sends the data is the source and the user that receives the data is a receiver. For data interchange to take place, the communicating devices must be a part of a system comprising of a combination of hardware and software. Its efficiency depends on four fundamental characteristics.
The Open Systems Interconnection model OSI model is a conceptual model that characterises and standardises the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard communication protocols. The model partitions the flow of data in a communication system into seven abstraction layers , from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. Classes of functionality are realized in software by standardized communication protocols. The OSI model was developed starting in the late s to support the emergence of the diverse computer networking methods that were competing for application in the large national networking efforts in France, the United Kingdom, and the United States. While attempting to provide a comprehensive description of networking, the model failed to garner reliance by the software architects in the design of the early Internet , which is reflected in the less prescriptive Internet Protocol Suite , principally sponsored under the auspices of the Internet Engineering Task Force IETF.
Data Communication is defined as exchange of data between two devices via some form of transmission media such as a cable, wire or it can be air or vacuum also. For occurrence of data communication, communicating devices must be a part of communication system made up of a combination of hardware or software devices and programs. Data Communication System Components : There are mainly five components of a data communication system:. Figure — Components of Data Communication System. A typical example of a data communication system is sending an e-mail. The user which send email act as sender, message is data which user wants to send, receiver is one whom user wants to send message, there are many protocols involved in this entire process, one of them is Simple Mail Transfer Protocol SMTP , both sender and receiver must have an internet connection which uses a wireless medium to send and receive email.
To reduce the design complexity, most of the data communication networks are organized as a series of layers or levels, each one build upon one below it (Divide.
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A communication protocol is a system of rules that allow two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax , semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware , software , or a combination of both. Communicating systems use well-defined formats for exchanging various messages.
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