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Quality Of Service
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc. In the field of computer networking and other packet-switched telecommunication networks, quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priorities to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. Quality of service is particularly important for the transport of traffic with special requirements. In particular, developers have introduced Voice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephony
Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone. Telephony is commonly referred to as the construction or operation of telephones and telephonic systems and as a system of telecommunications in which telephonic equipment is employed in the transmission of speech or other sound between points, with or without the use of wires. The term is also used frequently to refer to computer hardware, software, and computer network systems, that perform functions traditionally performed by telephone equipment. In this context the technology is specifically referred to as Internet telephony, or voice over Internet Protocol (VoIP). Overview The first telephones were connected directly in pairs. Each user had a separate telephone wired ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Delay
Network delay is a design and performance characteristic of a telecommunications network. It specifies the latency for a bit of data to travel across the network from one communication endpoint to another. It is typically measured in multiples or fractions of a second. Delay may differ slightly, depending on the location of the specific pair of communicating endpoints. Engineers usually report both the maximum and average delay, and they divide the delay into several parts: * Processing delay time it takes a router to process the packet header * Queuing delay time the packet spends in routing queues * Transmission delay time it takes to push the packet's bits onto the link * Propagation delay time for a signal to propagate through the media A certain minimum level of delay is experienced by signals due to the time it takes to transmit a packet serially through a link. This delay is extended by more variable levels of delay due to network congestion. IP network delays can range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streaming Video
Video on demand (VOD) is a media distribution system that allows users to access videos without a traditional video playback device and the constraints of a typical static broadcasting schedule. In the 20th century, broadcasting in the form of over-the-air programming was the most common form of media distribution. As Internet and IPTV technologies continued to develop in the 1990s, consumers began to gravitate towards non-traditional modes of content consumption, which culminated in the arrival of VOD on televisions and personal computers. Unlike broadcast television, VOD systems initially required each user to have an Internet connection with considerable bandwidth to access each system's content. In 2000, the Fraunhofer Institute IIS developed the JPEG2000 codec, which enabled the distribution of movies via Digital Cinema Packages. This technology has since expanded its services from feature-film productions to include broadcast television programmes and has led to lower bandw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latency (engineering)
Latency, from a general point of view, is a time delay between the cause and the effect of some physical change in the system being observed. Lag, as it is known in gaming circles, refers to the latency between the input to a simulation and the visual or auditory response, often occurring because of network delay in online games. Latency is physically a consequence of the limited velocity at which any physical interaction can propagate. The magnitude of this velocity is always less than or equal to the speed of light. Therefore, every physical system with any physical separation (distance) between cause and effect will experience some sort of latency, regardless of the nature of the stimulation at which it has been exposed to. The precise definition of latency depends on the system being observed or the nature of the simulation. In communications, the lower limit of latency is determined by the medium being used to transfer information. In reliable two-way communication syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Congestion
Network congestion in data networking and queueing theory is the reduced quality of service that occurs when a network node or link is carrying more data than it can handle. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of congestion is that an incremental increase in offered load leads either only to a small increase or even a decrease in network throughput. Network protocols that use aggressive retransmissions to compensate for packet loss due to congestion can increase congestion, even after the initial load has been reduced to a level that would not normally have induced network congestion. Such networks exhibit two stable states under the same level of load. The stable state with low throughput is known as congestive collapse. Networks use congestion control and congestion avoidance techniques to try to avoid collapse. These include: exponential backoff in protocols such as CSMA/CA in 802.11 and the similar CSMA/CD i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overprovisioning (networking)
Network planning and design is an iterative process, encompassing topological design, network-synthesis, and network-realization, and is aimed at ensuring that a new telecommunications network or service meets the needs of the subscriber and operator.Penttinen A., ''Chapter 10 – Network Planning and Dimensioning, Lecture Notes: S-38.145 - Introduction to Teletraffic Theory'', Helsinki University of Technology, Fall 1999. The process can be tailored according to each new network or service.Farr R.E., ''Telecommunications Traffic, Tariffs and Costs – An Introduction For Managers'', Peter Peregrinus Ltd, 1988. A network planning methodology A traditional network planning methodology in the context of business decisions involves five layers of planning, namely: * need assessment and resource assessment * short-term network planning * IT resource * long-term and medium-term network planning * operations and maintenance. Each of these layers incorporates plans for different t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Best-effort Network
Best-effort delivery describes a network service in which the network does ''not'' provide any guarantee that data is delivered or that delivery meets any quality of service. In a best-effort network, all users obtain best-effort service. Under best-effort, network performance characteristics such as network delay and packet loss depend on the current network traffic load, and the network hardware capacity. When network load increases, this can lead to packet loss, retransmission, packet delay variation, and further network delay, or even timeout and session disconnect. Best-effort can be contrasted with reliable delivery, which can be built on top of best-effort delivery (possibly without latency and throughput guarantees), or with virtual circuit schemes which can maintain a defined quality of service. Network examples Physical services The postal service (''snail mail'') physically delivers letters using a best-effort delivery approach. The delivery of a certain lette ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clearing (telecommunications)
Clearing, in telecommunications means: * A sequence of events used to disconnect a call and return to the ready state for the next call setup. It is sometimes, particularly in the context of common-channel signaling, called teardown. * Removal of data from an automated information system (AIS), its storage devices, and other peripheral devices with storage capacity, in such a way that the data may not be reconstructed using normal system capabilities (i.e. through the keyboard). ''Note:'' An AIS need not be disconnected from any external network before clearing takes place. Clearing enables a product to be reused within, but not outside of, a secure facility. It does not produce a declassified product by itself, but may be the first step in the declassification process. See also * Disengagement originator * National Information Systems Security Glossary Committee on National Security Systems Instruction No. 4009, National Information Assurance Glossary, published by the Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic Contract
If a network service (or application) wishes to use a broadband network (an ATM network in particular) to transport a particular kind of traffic, it must first inform the network about what kind of traffic is to be transported, and the performance requirements of that traffic.Hiroshi Saito, Teletraffic Technologies in ATM Networks, Artech House, 1993. . The application presents this information to the network in the form of a traffic contract. The Traffic descriptor When a connection is requested by an application, the application indicates to the network:Ferguson P., Huston G., Quality of Service: Delivering QoS on the Internet and in Corporate Networks, John Wiley & Sons, Inc., 1998. . *The Type of Service required. *The Traffic Parameters of each data flow in both directions. *The quality of service (QoS) Parameters requested in each direction. These parameters form the ''traffic descriptor'' for the connection. Type of Service Currently, five ATM Forum-defined servic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPTV
Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, IPTV offers the ability to stream the source media continuously. As a result, a client media player can begin playing the content (such as a TV channel) almost immediately. This is known as streaming media. Although IPTV uses the Internet protocol it is not limited to television streamed from the Internet (Internet television). IPTV is widely deployed in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes or other customer-premises equipment. IPTV is also used for media delivery around corporate and private networks. IPTV in the telecommunications arena is notable for its ongoing standardisation process (e.g., European Telecommunications Standards Institute). IPTV service ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplayer Online Game
A multiplayer video game is a video game in which more than one person can play in the same game environment at the same time, either locally on the same computing system (couch co-op), on different computing systems via a local area network, or via a wide area network, most commonly the Internet (e.g. ''World of Warcraft'', ''Call of Duty'', ''DayZ''). Multiplayer games usually require players to share a single game system or use networking technology to play together over a greater distance; players may compete against one or more human contestants, work cooperatively with a human partner to achieve a common goal, or supervise other players' activity. Due to multiplayer games allowing players to interact with other individuals, they provide an element of social communication absent from single-player games. History Non-networked Some of the earliest video games were two-player games, including early sports games (such as 1958's ''Tennis For Two'' and 1972's ''Pong''), earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voice Over IP
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of speech, voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the provisioning of communications services (voice, fax, Short Message Service, SMS, voice-messaging) over the Internet, rather than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS). Overview The steps and principles involved in originating VoIP telephone calls are similar to traditional digital telephony and involve signaling, channel setup, digitization of the analog voice signals, and encoding. Instead of being transmitted over a circuit-switched network, the digital information is packetized and transmission occurs as IP packets over a packet-switched network. They transport media streams using spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
