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Bandwidth-delay Product
In data communications, the bandwidth-delay product is the product of a data link's capacity (in bits per second) and its round-trip delay time (in seconds). The result, an amount of data measured in bits (or bytes), is equivalent to the maximum amount of data on the network circuit at any given time, i.e., data that has been transmitted but not yet acknowledged. The bandwidth-delay product was originally proposed as a rule of thumb for sizing router buffers in conjunction with congestion avoidance algorithm random early detection (RED). A network with a large bandwidth-delay product is commonly known as a long fat network (LFN). As defined in , a network is considered an LFN if its bandwidth-delay product is significantly larger than 105 bits (12,500 bytes). Details Ultra-high speed local area networks (LANs) may fall into this category, where protocol tuning is critical for achieving peak throughput, on account of their extremely high bandwidth, even though their delay is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Data Communications
Data communication, including data transmission and data reception, is the transfer of data, signal transmission, transmitted and received over a Point-to-point (telecommunications), point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication using radio spectrum, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal. ''Analog transmission'' is a method of conveying voice, data, image, signal or video information using a continuous signal that varies in amplitude, phase, or some other property in proportion to that of a variable. The messages are either represented by a sequence of pulses by means of a line code (''baseband transmission''), or by a limited set of continuously varying waveforms (''passband transmission''), using a digital modulation method. The passband modulation and cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Cable Internet
In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line (DSL) and fiber to the premises, cable Internet access provides network edge connectivity ( last mile access) from the Internet service provider to an end user. It is integrated into the cable television infrastructure analogously to DSL, which uses the existing telephone network. Cable TV networks and telecommunications networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, and satellite internet access. Hardware and bit rates Broadband cable Internet access requires a cable modem at the customer's premises and a cable modem termination system (CMTS) at a cable operator facility, typically a cable television headend. The two are connected via coaxial cable to a hybrid fibre-coaxial ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Kibibyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Bufferbloat
Bufferbloat is the undesirable latency that comes from a router or other network equipment buffering too many data packets. Bufferbloat can also cause packet delay variation (also known as jitter), as well as reduce the overall network throughput. When a router or switch is configured to use excessively large buffers, even very high-speed networks can become practically unusable for many interactive applications like voice over IP (VoIP), audio streaming, online gaming, and even ordinary web browsing. Some communications equipment manufacturers designed unnecessarily large buffers into some of their network products. In such equipment, bufferbloat occurs when a network link becomes congested, causing packets to become queued for long periods in these oversized buffers. In a first-in first-out queuing system, overly large buffers result in longer queues and higher latency, and do not improve network throughput. It can also be induced by specific slow-speed connections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Internet2
Internet2 is a not-for-profit United States computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...ing consortium led by members from the research and education communities, industry, and government. The Internet2 consortium administrative headquarters are located in Ann Arbor, Michigan, with offices in Washington, D.C., and Emeryville, California. As of November 2013, Internet2 has over 500 members including 251 institutions of higher education, 9 partners and 76 members from industry, over 100 research and education networks or connector organizations, and 67 affiliate members. Internet2 operates the Internet2 Network, an Internet Protocol network using optical fiber that delivers network services for research and education, and provides a secure network te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Satellite Internet
Satellite Internet access is Internet access provided through communication satellites; if it can sustain high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using the to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space. History Following the launch of the first satellite, Sputnik 1, by the Soviet Union in October 1957, the US successfully launched the Explorer 1 satellite in 1958. The first commercial communications satellite was Telstar 1, built by Bell Labs and launched in July 1962. The idea of a geosynchronous satellite—one that could orbit the Earth above the equator and remain fixed by following the Earth's rotation—was first propos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Protocol Spoofing
Protocol spoofing is used in data communications to improve performance in situations where an existing protocol is inadequate, for example due to long delays or high error rates. Spoofing techniques In most applications of protocol spoofing, a communications device such as a modem or router simulates ("spoofs") the remote endpoint of a connection to a locally attached host, while using a more appropriate protocol to communicate with a compatible remote device that performs the equivalent spoof at the other end of the communications link. File transfer spoofing Error correction and file transfer protocols typically work by calculating a checksum or CRC for a block of data known as a ''packet'', and transmitting the resulting number at the end of the packet. At the other end of the connection, the receiver re-calculates the number based on the data it received and compares that result to what was sent from the remote machine. If the two match the packet was transmitted correctl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Agile-SD
Transmission Control Protocol (TCP) uses a congestion control algorithm that includes various aspects of an additive increase/multiplicative decrease (AIMD) scheme, along with other schemes including slow start and a congestion window (CWND), to achieve congestion avoidance. The TCP congestion-avoidance algorithm is the primary basis for congestion control in the Internet. Per the end-to-end principle, congestion control is largely a function of internet hosts, not the network itself. There are several variations and versions of the algorithm implemented in protocol stacks of operating systems of computers that connect to the Internet. To avoid congestive collapse, TCP uses a multi-faceted congestion-control strategy. For each connection, TCP maintains a CWND, limiting the total number of unacknowledged packets that may be in transit end-to-end. This is somewhat analogous to TCP's sliding window used for flow control. Additive increase/multiplicative decrease The additive in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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Compound TCP
Compound TCP (CTCP) is a Microsoft algorithm that was introduced as part of the Windows Vista and Window Server 2008 TCP stack. It is designed to aggressively adjust the sender's congestion window to optimise TCP for connections with large bandwidth-delay products while trying not to harm fairness (as can occur with HSTCP). It is also available for Linux, as well as for Windows XP and Windows Server 2003 via a hotfix. Principles of operation Like FAST TCP and TCP Vegas, Compound TCP uses estimates of queuing delay as a measure of congestion; if the queuing delay is small, it assumes that no links on its path are congested, and rapidly increases its rate. Unlike them, it does not seek to maintain a constant number of packets queued. Compound TCP maintains two congestion windows: a regular AIMD window and a delay-based window. The size of the actual sliding window used is the sum of these two windows. The AIMD window is increased the same way that TCP Reno increases it. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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H-TCP
H-TCP is another implementation of TCP with an optimized congestion control algorithm for high-speed networks with high latency (LFN: Long Fat Networks). It was created by researchers at the Hamilton Institute in Ireland. H-TCP is an optional module in Linux since kernel version 2.6, and has been implemented for FreeBSD 7. Principles of operation H-TCP is a loss-based algorithm, using additive-increase/multiplicative-decrease (AIMD) to control TCP's congestion window. It is one of many TCP congestion avoidance algorithms which seeks to increase the aggressiveness of TCP on high bandwidth-delay product (BDP) paths, while maintaining "TCP friendliness" for small BDP paths. H-TCP increases its aggressiveness (in particular, the rate of additive increase) as the time since the previous loss increases. This avoids the problem encountered by HSTCP and BIC TCP of making flows more aggressive if their windows are already large. Thus, new flows can be expected to converge to fai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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CUBIC TCP
CUBIC is a network congestion avoidance algorithm for TCP which can achieve high bandwidth connections over networks more quickly and reliably in the face of high latency than earlier algorithms. It helps optimize long fat networks. In 2006, the first CUBIC implementation was released in Linux kernel 2.6.13. Since kernel version 2.6.19, CUBIC replaces BIC-TCP as the default TCP congestion control algorithm in the Linux kernel. MacOS adopted TCP CUBIC with the OS X Yosemite release in 2014, while the previous release OS X Mavericks still used TCP New Reno. Microsoft adopted it by default in Windows 10.1709 Fall Creators Update (2017), and Windows Server 2016 1709 update. Characteristics CUBIC is a less aggressive and more systematic derivative of BIC TCP, in which the window size is a cubic function of time since the last congestion event, with the inflection point set to the window size prior to the event. Because it is a cubic function, there are two components t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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BIC TCP
BIC TCP (Binary Increase Congestion control) is one of the TCP congestion control, congestion control algorithms that can be used for Transmission Control Protocol (TCP). BIC is optimized for high-speed networks with high latency: so-called long fat networks. For these networks, BIC has significant advantage over previous congestion control schemes in correcting for severely underutilized bandwidth. BIC implements a unique congestion window (cwnd) algorithm. This algorithm tries to find the maximum cwnd by searching in three parts: Binary search algorithm, binary search increase, Additive increase/multiplicative decrease, additive increase, and slow start. When a network failure occurs, the BIC uses multiplicative decrease in correcting the cwnd. BIC TCP is implemented and used by default in Linux kernels 2.6.8 and above. The default implementation was again changed to CUBIC TCP in the 2.6.19 version. Algorithm Define the following variables: Smax: the maximum increme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |