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Data Network Identification Code
X.121 is the ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between public data networks (PDNs), connecting two network user addresses (NUAs). It consists of a maximum of fourteen binary-coded decimal digits and is sent over the Packet Layer Protocol (PLP) after the packet type identifier (PTI). Description The address is made up of the international data number (IDN), which consists of two fields: the 4 digit data network identification code (DNIC) and the (up to) 10 digit national terminal number (NTN). The DNIC has three digits to identify the country (one to identify a zone and two to identify the country within the zone) and one to identify the PDN (allowing only ten in each country). The NTN identifies the exact network device (DTE, data terminal equipment) in the packet-switched network (PSN) and is often provided as an NUA. There are no rules to the structure of the NTN. IPv4 addresses can be mapped t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T
The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating Standardization, standards for telecommunications and Information Communication Technology, such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, convenes every four years. ITU-T has a permanent Secretariat (administrative office), secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Seizo Onoe (of Japan), whose 4-year term commenced on 1 January 2023. Seizo Onoe succeeded Chaesub Lee of South Korea, who was director from 1 J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protocol Suite
The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the ''suite'' is the definition of the communication protocols, and the ''stack'' is the software implementation of them. Individual protocols within a suite are often designed with a single purpose in mind. This modularization simplifies design and evaluation. Because each protocol module usually communicates with two others, they are commonly imagined as layers in a stack of protocols. The lowest protocol always deals with low-level interaction with the communications hardware. Each higher layer adds additional capabilities. User applications usually deal only with the topmost layers. General protocol suite description T ~ ~ ~ T ____ Imagine three computers: ''A'', ''B'', and ''C''. ''A'' and ''B'' both have radio equipment and can communicate via the airwaves using a suitable net ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Circuit
A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is first established across the network between two endpoints. The network, rather than having a fixed data rate reservation per connection as in circuit switching, takes advantage of the statistical multiplexing on its transmission links, an intrinsic feature of packet switching. A 1978 standardization of virtual circuits by the CCITT imposes per-connection Flow control (data), flow controls at all user-to-network and network-to-network interfaces. This permits participation in congestion control and reduces the likelihood of packet loss in a heavily loaded network. Some circuit protocols provide Reliability (computer networking), reliable communication service through the use of data retransmissions invoked by error detection and automatic repeat request (ARQ). Before a virtual circuit may be used, it must be established between network nodes in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Public Data Network
A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public packet switching networks were RETD in Spain (1972), the experimental RCP network in France (1972) and Telenet in the United States (1975). "Public data network" was the common name given to the collection of X.25 providers, the first of which were Telenet in the U.S. and DATAPAC in Canada (both in 1976), and Transpac in France (in 1978). The International Packet Switched Service (IPSS) was the first commercial and international packet-switched network (1978). The networks were interconnected with gateways using X.75. These combined networks had large global coverage during the 1980s and into the 1990s. The networks later provided the infrastructure for the early Internet. Description In communications, a PDN is a circuit- or p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network User Address
Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics * Networks, a graph with attributes studied in network theory ** Scale-free network, a network whose degree distribution follows a power law ** Small-world network, a mathematical graph in which most nodes are not neighbors, but have neighbors in common * Flow network, a directed graph where each edge has a capacity and each edge receives a flow Biology * Biological network, any network that applies to biological systems * Ecological network, a representation of interacting species in an ecosystem * Neural network, a network or circuit of neurons Technology and communication * Artificial neural network, a computing system inspired by animal brains * Broadcast network, radio stations, television stations, or other electronic media outlet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary-coded Decimal
In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for a sign or other indications (e.g. error or overflow). In byte-oriented systems (i.e. most modern computers), the term ''unpacked'' BCD usually implies a full byte for each digit (often including a sign), whereas ''packed'' BCD typically encodes two digits within a single byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9. The precise four-bit encoding, however, may vary for technical reasons (e.g. Excess-3). The ten states representing a BCD digit are sometimes called '' tetrades'' (the nibble typically needed to hold them is also known as a tetrade) while the unused, don't care-states are named ''pseudo-tetrad(e)s'', ''pseudo-decimals'', or ''pseudo-decimal digits''. BCD's main virtue, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Layer Protocol
Packet Layer Protocol or PLP operates on the Network-Layer of the OSI model for the X.25 protocol suite. It's responsible for addressing, routing, and delivering data packets across different networks. PLP manages the packet exchanges between DTE (data terminal) devices across VCs (virtual circuits). PLP also can be used on ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. ... using Link Access Procedures, D channel (LAPD). There are 5 modes of PLP: call setup, data transfer, idle, call clearing, and restarting. * ''Call setup mode'' is used to create VCs (virtual circuits) between DTE devices. A PLP uses the 14-digit X.121 addressing scheme to set up the virtual circuit. * ''Data transfer mode'' is used to send data between DTE devices across a virtual circuit. At this level ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Terminal Equipment
Data terminal equipment (DTE) is an end instrument that converts user information into signals or reconverts received signals. It is also called data processing terminal equipment or tail circuit. A DTE device communicates with the data circuit-terminating equipment (DCE), such as a modem. The DTE/DCE classification was introduced by IBM. A DTE is the functional unit of a data station (''station'', ''terminal'') that serves as a data source or a data sink and provides for the data communication control function to be performed in accordance with the link protocol. Usually, the DTE device is the terminal (or a computer emulating a terminal), and the DCE is a modem or another carrier-owned device. The data terminal equipment may be a single piece of equipment or an interconnected subsystem of multiple pieces of equipment that perform all the required functions necessary to permit users to communicate. A user interacts with the DTE (e.g. through a human-machine interface) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet-switched Network
In telecommunications, packet switching is a method of grouping data into short messages in fixed format, i.e. '' packets,'' that are transmitted over a digital network. Packets consist of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. During the early 1960s, American engineer Paul Baran developed a concept he called ''distributed adaptive message block switching'', with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted then-established principles of pre-allocation of network bandwidth, exemplified by the development of telecommun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPv4 Address Exhaustion
IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 1000000000 (number), billion addresses available, depletion has been anticipated since the late 1980s when the Internet started experiencing dramatic growth. This depletion is one of the reasons for the development and IPv6 deployment, deployment of its successor protocol, IPv6. IPv4 and IPv6 coexist on the Internet. The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registry, regional Internet registries (RIRs) responsible in their designated territories for assignment to end users and local Internet registry, local Internet registries, such as Internet service providers. The main market forces that accelerated IPv4 address depletion included the rapidly growing number of Internet users, always-on devices, and mobile devices. The anticipated shortage has been the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Videotex
Videotex (or interactive videotex) was one of the earliest implementations of an end-user information system. From the late 1970s to early 2010s, it was used to deliver information (usually pages of text) to a user in computer-like format, typically to be displayed on a television or a dumb terminal. In a strict definition, videotex is any system that provides interactive content and displays it on a video monitor such as a television, typically using modems to send data in both directions. A close relative is teletext, which sends data in one direction only, typically encoded in a television signal. All such systems are occasionally referred to as ''viewdata''. Unlike the modern Internet, traditional videotex services were highly centralized. Videotex in its broader definition can be used to refer to any such service, including teletext, the Internet, bulletin board systems, online service providers, and even the arrival/departure displays at an airport. This usage is no longe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Layer Protocols
Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics * Networks, a graph with attributes studied in network theory ** Scale-free network, a network whose degree distribution follows a power law ** Small-world network, a mathematical graph in which most nodes are not neighbors, but have neighbors in common * Flow network, a directed graph where each edge has a capacity and each edge receives a flow Biology * Biological network, any network that applies to biological systems * Ecological network, a representation of interacting species in an ecosystem * Neural network, a network or circuit of neurons Technology and communication * Artificial neural network, a computing system inspired by animal brains * Broadcast network, radio stations, television stations, or other electronic media ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
