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ADCCP
In telecommunications, Advanced Data Communication Control Procedures (or Protocol) (ADCCP) is a bit-oriented data link layer protocol developed by the American National Standards Institute. It is functionally equivalent to the ISO High-Level Data Link Control (HDLC) protocol. Although the ISO and ANSI standards writers coordinated their work, so the differences between the standards are mainly editorial, there is one meaningful difference: ADCCP's definition of the basic subset required to implement balanced asynchronous mode includes the RSET frame, while HDLC makes it optional. One major difference between the two is the unnumbered (U) format. When extended (7-bit) sequence numbers are used, I and S frames have two-byte control fields. Like early versions of HDLC, ADCCP specifies a 2-byte control field format with the P/F flag duplicated. Later HDLC specifications, in particular ISO/IEC 13239, changed that to specify that U frames have 1-byte control fields in all cases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-Level Data Link Control
High-Level Data Link Control (HDLC) is a communication protocol used for transmitting data between devices in telecommunication and networking. Developed by the International Organization for Standardization (ISO), it is defined in the standard ISO/IEC 13239:2002. HDLC ensures reliable data transfer, allowing one device to understand data sent by another. It can operate with or without a continuous connection between devices, making it versatile for various network configurations. Originally, HDLC was used in multi-device networks, where one device acted as the master and others as slaves, through modes like Normal Response Mode (NRM) and Asynchronous Response Mode (ARM). These modes are now rarely used. Currently, HDLC is primarily employed in point-to-point connections, such as between routers or network interfaces, using a mode called Asynchronous Balanced Mode (ABM). History HDLC is based on IBM's SDLC protocol, which is the layer 2 protocol for IBM's Systems Network A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-synchronizing Code
In coding theory, especially in telecommunications, a self-synchronizing code is a uniquely decodable code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. Put another way, a set of strings (called "code words") over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring. Every self-synchronizing code is a prefix code, but not all prefix codes are self-synchronizing. Other terms for self-synchronizing code are synchronized code or, ambiguously, comma-free code. A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream; external synchronization is not required. Self-synchronizing codes also allow recovery from uncor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent Session (computer science), communication sessions. Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the electrical telegraph, telegraph, telephone, television, and radio. Early telecommunication networks used metal wires as the medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi, who won the 1909 Nobel Prize in Physics. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bit-oriented Protocol
A bit-oriented protocol is a communications protocol that sees the transmitted data as an ''opaque'' stream of bits with no semantics, or meaning. Control codes are defined in terms of bit sequences instead of characters. Bit oriented protocol can transfer data frames regardless of frame contents. It can also be stated as "bit stuffing". Synchronous framing High-Level Data Link Control may work like this: * Each frame begins and ends with a special bit pattern 01111110, called a flag byte. * A bit stuffing In data transmission and telecommunications, bit stuffing (also known—uncommonly—as positive justification) is the insertion of non-information bits into data. Stuffed bits should not be confused with overhead bits. Bit stuffing is used f ... technique is used to prevent the receiver from detecting the special flag byte in user data e.g. whenever the sender's data link layer encounters 5 consecutive 1 (one) in the data, it automatically stuffs 0 into the outgoing strea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Link Layer
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer. The data link layer is concerned with local delivery of frames between nodes on the same level of the network. Data-link frames, as these protocol data units are called, do not cross the boundaries of a local area network. Inter-network routing and global addressing are higher-layer functions, allowing data-link protocols to focus on local delivery, addressing, and media arbitration. In this way, the data link layer is analogous to a neighborhood traffic cop; it endeavors to arbitrate between parties contending for access to a medium, without c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communication Protocol
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics (computer science), semantics, and synchronization of communication and possible Error detection and correction, error recovery methods. Protocols may be implemented by Computer hardware, 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 predetermined for that particular situation. The specified behavior is typically independent of how it is to be Implementation, implemented. Communication protocols have to be agreed upon by the parties involved. To reach an agreement, a protocol may be developed into a technical standard. A programming language describes the same for computations, so there ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American National Standards Institute
The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide. ANSI accredits standards that are developed by representatives of other standards organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards. The organization's headquarters are in Washington, D.C. ANSI's operations office is located in New York City. The ANSI annual operating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Link Layer
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer. The data link layer is concerned with local delivery of frames between nodes on the same level of the network. Data-link frames, as these protocol data units are called, do not cross the boundaries of a local area network. Inter-network routing and global addressing are higher-layer functions, allowing data-link protocols to focus on local delivery, addressing, and media arbitration. In this way, the data link layer is analogous to a neighborhood traffic cop; it endeavors to arbitrate between parties contending for access to a medium, without c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
