Network performance
Encyclopedia
Network performance refers to the service quality
of a telecommunications product as seen by the customer. It should not be seen merely as an attempt to get "more through" the network.
The following list gives examples of Network Performance measures for a circuit-switched network and one type of packet-switched network, viz. ATM:
There are many different ways to measure the performance of a network, as each network is different in nature and design. Performance can also be modelled instead of measured; one example of this is using state transition diagrams to model queuing performance in a circuit-switched network. These diagrams allow the network planner to analyze how the network will perform in each state, ensuring that the network will be optimally designed.
The 8-second rule is an old (by Internet
standards) way of measuring the adequate response time of a webserver through different bandwidth
connections. It specified that if the load-time of a web page exceeds eight seconds, users are unlikely to wait, or "stick around", for its completion. In order to increase the "stickiness" of a website
, faster ways to deliver the content to the user needed to be devised. These included stripping away unnecessary HTML
code and using fewer images.
It is generally believed that this rule no longer applies, since a much higher percentage of Internet users now have broadband
available, making almost every website load up much faster, in some cases
in less than a second. However, the rule has remained as a rough unit to measure the performance of a webserver.
means a "faster" connection. However, throughput, latency
, the type of information transmitted, and the way that information is applied all affect the perceived speed of a connection.
The Time Window is the period over which the throughput is measured. Choice of an appropriate time window will often dominate calculations of throughput, and whether latency is taken into account or not will determine whether the latency affects the throughput or not.
connections, the large bandwidth-delay product
of high latency connections, combined with relatively small TCP window sizes on many devices, effectively causes the throughput of a high latency connection to drop sharply with latency. This can be remedied with various techniques, such as increasing the TCP congestion window size, or more drastic solutions, such as packet coalescing, TCP acceleration, and forward error correction, all of which are commonly used for high latency satellite links.
TCP acceleration converts the TCP packets into a stream that is similar to UDP
. Because of this, the TCP acceleration software must provide its own mechanisms to ensure the reliability of the link, taking the latency and bandwidth of the link into account, and both ends of the high latency link must support the method used.
implemented by NASA is one such system that must cope with these problems. Largely latency driven, the GAO has criticized the current architecture. Several different methods have been proposed to handle the intermittent connectivity and long delays between packets, such as delay-tolerant networking .
feel that responses are "instant" when delays are less than 100 ms from click to response. Latency and throughput together affect the perceived speed of a connection. However, the perceived performance
of a connection can still vary widely, depending in part on the type of information transmitted and how it is used.
In a 2001 study, it was found that a typical web page was 53,400 bytes in size.
Round-trip packet latency over the Internet is fairly low – typically less than a tenth of a second across North America – and an average web page of 30-100 kilobytes would normally transfer fully in 10–30 seconds, over a 56-kbit/s
modem
, which yields a 3 kbit/s transfer rate. If a user had to wait 10–30 seconds to see anything, after every web-page click, it would be intolerable.
Because latency is so important, the HTTP protocol and HTML
markup language were invented to reduce the rendering time of hypertext over the internet. These protocols allow incremental rendering, meaning that page text can begin display after the first packet arrives. HTTP and nearly all browsers support gzip (compressed) transfer encoding, which can typically compress text by 2x. Moreover, HTTP 1.0 and later protocols support a rich set of caching primitives, allowing content to be stored closer to the user, in both browser-caches and ISP proxy-caches, all to reduce latency. And finally, in the early days of HTTP, interlaced photos were transmitted via GIF
, which allowed a rough version of an embedded picture to appear when only half the scan lines had arrived. A few years later JPEG
was invented, allowing an almost arbitrary tradeoff between latency and image quality. These optimizations of HTTP and HTML, GIF, and JPEG were crucial to reducing latency and improving the perceived performance of the World Wide Web.
Hence, when a user clicks on a web page, there is a delay of 500-550 milliseconds to transfer a 1500-byte packet over a 56 kbit/s modem, before the user can begin to see up to 3,000 bytes (uncompressed) of text. A DSL line with a throughput of 256kbit/s would produce a delay of roughly 60-110 ms, which would be perceived as an "instant" response.
By comparison, to transfer the contents of a DVD
over a modem could take a week or more at a 56 kbit/s modem rate. Simply packing the DVD into an envelope and mailing it
could be faster.
and/or a Local Area Network
to coordinate a multiplayer game
experience among two or more players, each of whom is running a copy of the game on a local game system (typically a video game console
or gaming computer
), with messages sent among the multiple game systems (either directly or through a game server
reporting the actions of each player so that all the game systems stay synchronized). If the nature of the game is such that the game's local action cannot proceed until it synchronizes with one or more remote game systems, then the latency of the Internet and/or LAN will accordingly delay the responsiveness of a game system. Although such systems may only require very low throughput (e.g. messages of game controller
actions may be only a few kilobits per second), the latency of the Internet and/or LAN must be low enough to meet the requirements of the game.
The maximum acceptable latency is game-type dependent. For example, generally, twitch gameplay games such as a first-person shooter
like Quake 3 require lower latency for the best experience, while generally, a turn-based game such as chess
can tolerate higher latency. But, it entirely depends on the specifics of each game. For example, fast chess is a turn-based game that may have low latency requirements. And, in the case of twitch games, some games can be designed such that only events that impact the outcome of the game are subject to synchronization latency, allowing for fast local response time most of the time.
Cloud gaming
is a type of online gaming where the entire game is hosted on a game server in a data center, and the user is only running a thin client
locally that forwards game controller
upstream to the game server. The game server then renders the next frame of the game video which is compressed using low-latency video compression and is sent downstream and decompressed by the thin client. For the cloud gaming experience to be acceptable, the round-trip latency of all elements of the cloud gaming system (the thin client, the Internet and/or LAN connection the game server, the game execution on the game server, the video and audio compression and decompression, and the display of the video on a display device
) must be low enough that the user perception is that the game is running locally. Because of such tight latency requirements, distance considerations of the speed of light
through optical fiber
come into play, currently limiting the distance between a user and a cloud gaming game server to approximately 1000 miles, according to OnLive
, the only company thus far operating a cloud gaming service.
Online game systems utilizing a wireless network
may be subject to significant latency, depending on the architecture of the wireless network and local electromagnetic interference
impacting that network. Although radio propagation
through air is faster than light through optical fiber, wireless systems are often shared among many users and may suffer from latency incurred due to network congestion
which can trigger bufferbloat
related issues, or due to network protocols that introduce latency. And, in the event of electromagnetic interference
, transmitted packets may be lost, requiring a retransmission which also incurs latency.
Service quality
Service quality involves a comparison of expectations with performance.According to Lewis and Booms service quality is a measure of how well a delivered service matches the customers expectations....
of a telecommunications product as seen by the customer. It should not be seen merely as an attempt to get "more through" the network.
The following list gives examples of Network Performance measures for a circuit-switched network and one type of packet-switched network, viz. ATM:
- Circuit-switched networks: In circuit switched networks, network performance is synonymous with the grade of serviceGrade of serviceIn telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service and the quality of service ....
. The number of rejected calls is a measure of how well the network is performing under heavy traffic loads. Other types of performance measures can include noise, echo and so on.
- ATM: In an Asynchronous Transfer ModeAsynchronous Transfer ModeAsynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
(ATM) network, performance can be measured by line rate, quality of serviceQuality of serviceThe quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
(QoS), data throughput, connect time, stability, technology, modulation technique and modem enhancements.
There are many different ways to measure the performance of a network, as each network is different in nature and design. Performance can also be modelled instead of measured; one example of this is using state transition diagrams to model queuing performance in a circuit-switched network. These diagrams allow the network planner to analyze how the network will perform in each state, ensuring that the network will be optimally designed.
8-second rule
A June 2001 Zona Research report entitled "The Need for Speed II" found that the average web user will wait about eight seconds for a page to download, but that current average download time across backbone connection on most web sites is almost ten seconds.The 8-second rule is an old (by Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
standards) way of measuring the adequate response time of a webserver through different bandwidth
Bandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
connections. It specified that if the load-time of a web page exceeds eight seconds, users are unlikely to wait, or "stick around", for its completion. In order to increase the "stickiness" of a website
Website
A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...
, faster ways to deliver the content to the user needed to be devised. These included stripping away unnecessary HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
code and using fewer images.
It is generally believed that this rule no longer applies, since a much higher percentage of Internet users now have broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
available, making almost every website load up much faster, in some cases
in less than a second. However, the rule has remained as a rough unit to measure the performance of a webserver.
Relationship between latency and throughput
A common concern in the development or procurement of a telecommunications system is a simple question: "will my data arrive fast enough?". This question in fact contains many subtle parts, based on the interplay of several factors. The perceived 'fastness' (speed being a scientific quantity related to propagation and so is not used in this context) is highly dependent on user requirements and measurement technique. A common misunderstanding is that having greater throughputThroughput
In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...
means a "faster" connection. However, throughput, latency
Latency (engineering)
Latency is a measure of time delay experienced in a system, the precise definition of which depends on the system and the time being measured. Latencies may have different meaning in different contexts.-Packet-switched networks:...
, the type of information transmitted, and the way that information is applied all affect the perceived speed of a connection.
Terms
Throughput is the number of messages successfully delivered per unit time. Throughput is controlled by available bandwidth, as well as the available signal-to-noise ratio and hardware limitations. Throughput for the purpose of this article will be understood to be measured from the arrival of the first bit of data at the receiver, to decouple the concept of throughput from the concept of latency. For discussions of this type the terms 'throughput' and 'bandwidth' are often used interchangeably.The Time Window is the period over which the throughput is measured. Choice of an appropriate time window will often dominate calculations of throughput, and whether latency is taken into account or not will determine whether the latency affects the throughput or not.
Interplay of factors
All of the factors above, coupled with user requirements and user perceptions, play a role in determining the perceived 'fastness' or utility, of a network connection. The relationship between throughput, latency, and user experience is most aptly understood in the context of a shared network medium, and as a scheduling problem. For systems that are heavily dominated by either latency or throughput considerations.Physical limitations
- The speed of lightSpeed of lightThe speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
imposes a minimum propagation time on all electromagnetic signals. It is not possible to reduce the latency below t=(distance)/(speed of light).
- The available channel bandwidth and achievable signal-to-noise ratio dominate the throughput. It is not generally possible to send more data than dictated by the Shannon-Hartley Theorem.
Algorithms and protocols
For some systems, latency and throughput are coupled entities. In TCP/IP, latency can also directly affect throughput. In TCPTransmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
connections, the large bandwidth-delay product
Bandwidth-delay product
In data communications, bandwidth-delay product refers to the product of a data link's capacity and its end-to-end delay . The result, an amount of data measured in bits , is equivalent to the maximum amount of data on the network circuit at any given time, i.e. data that has been transmitted but...
of high latency connections, combined with relatively small TCP window sizes on many devices, effectively causes the throughput of a high latency connection to drop sharply with latency. This can be remedied with various techniques, such as increasing the TCP congestion window size, or more drastic solutions, such as packet coalescing, TCP acceleration, and forward error correction, all of which are commonly used for high latency satellite links.
TCP acceleration converts the TCP packets into a stream that is similar to UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
. Because of this, the TCP acceleration software must provide its own mechanisms to ensure the reliability of the link, taking the latency and bandwidth of the link into account, and both ends of the high latency link must support the method used.
Examples of latency or throughput dominated systems
Many systems can be characterized as dominated either by throughput limitations or by latency limitations in terms of end-user utility or experience. In some cases, hard limits such as the speed of light present unique problems to such systems and nothing can be done to correct this. Other systems allow for significant balancing and optimization for best user experience.Satellite telephony
A telecom satellite in geosynchronous orbit imposes a path length of at least 71000 km between transmitter and receiver. which means a minimum delay between message request and message receipt, or latency of 473 ms. This delay can be very noticeable and affects satellite phone service regardless of available throughput capacity.Deep space communication
These long path length considerations are exacerbated when communicating with space probes and other long-range targets beyond Earth's atmosphere. The Deep Space NetworkDeep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
implemented by NASA is one such system that must cope with these problems. Largely latency driven, the GAO has criticized the current architecture. Several different methods have been proposed to handle the intermittent connectivity and long delays between packets, such as delay-tolerant networking .
Even deeper space communication
At interstellar distances, the difficulties in designing radio systems that can achieve any throughput at all are massive. In these cases, maintaining communication is a bigger issue than how long that communication takes.Offline data transport
Transportation is concerned almost entirely with throughput, which is why physical deliveries of backup tape archives are still largely done by vehicle.Web surfing
Users browsing the InternetInternet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
feel that responses are "instant" when delays are less than 100 ms from click to response. Latency and throughput together affect the perceived speed of a connection. However, the perceived performance
Perceived performance
Perceived performance, in computer engineering, refers to how quickly a software feature appears to perform its task. The concept applies mainly to user acceptance aspects....
of a connection can still vary widely, depending in part on the type of information transmitted and how it is used.
In a 2001 study, it was found that a typical web page was 53,400 bytes in size.
Round-trip packet latency over the Internet is fairly low – typically less than a tenth of a second across North America – and an average web page of 30-100 kilobytes would normally transfer fully in 10–30 seconds, over a 56-kbit/s
56 kbit/s line
A 56 kbit/s line is a digital connection capable of carrying 56 kilobits per second , or 56,000 bit/s, the data rate of a classical single channel digital telephone line in North America...
modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
, which yields a 3 kbit/s transfer rate. If a user had to wait 10–30 seconds to see anything, after every web-page click, it would be intolerable.
Because latency is so important, the HTTP protocol and HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
markup language were invented to reduce the rendering time of hypertext over the internet. These protocols allow incremental rendering, meaning that page text can begin display after the first packet arrives. HTTP and nearly all browsers support gzip (compressed) transfer encoding, which can typically compress text by 2x. Moreover, HTTP 1.0 and later protocols support a rich set of caching primitives, allowing content to be stored closer to the user, in both browser-caches and ISP proxy-caches, all to reduce latency. And finally, in the early days of HTTP, interlaced photos were transmitted via GIF
GIF
The Graphics Interchange Format is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability....
, which allowed a rough version of an embedded picture to appear when only half the scan lines had arrived. A few years later JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
was invented, allowing an almost arbitrary tradeoff between latency and image quality. These optimizations of HTTP and HTML, GIF, and JPEG were crucial to reducing latency and improving the perceived performance of the World Wide Web.
Hence, when a user clicks on a web page, there is a delay of 500-550 milliseconds to transfer a 1500-byte packet over a 56 kbit/s modem, before the user can begin to see up to 3,000 bytes (uncompressed) of text. A DSL line with a throughput of 256kbit/s would produce a delay of roughly 60-110 ms, which would be perceived as an "instant" response.
By comparison, to transfer the contents of a DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
over a modem could take a week or more at a 56 kbit/s modem rate. Simply packing the DVD into an envelope and mailing it
Sneakernet
Sneakernet is an informal term describing the transfer of electronic information, especially computer files, by physically couriering removable media such as magnetic tape, floppy disks, compact discs, USB flash drives, or external hard drives from one computer to another. This is usually in lieu...
could be faster.
Online gaming
Some online games utilize the InternetInternet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
and/or a Local Area Network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
to coordinate a multiplayer game
Multiplayer game
A multiplayer video game is one which more than one person can play in the same game environment at the same time. Unlike most other games, computer and video games are often single-player activities that put the player against preprogrammed challenges and/or AI-controlled opponents, which often...
experience among two or more players, each of whom is running a copy of the game on a local game system (typically a video game console
Video game console
A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...
or gaming computer
Gaming computer
A gaming computer is a personal computer that is capable of playing computationally demanding video games. Gaming computers are very similar to conventional PCs, with the main difference being the addition of a performance-oriented video card. Gaming computers are often associated with enthusiast...
), with messages sent among the multiple game systems (either directly or through a game server
Game server
A game server is a remotely or locally run server used by game clients to play multiplayer video games. Most video games played over the Internet operate via a connection to a game server...
reporting the actions of each player so that all the game systems stay synchronized). If the nature of the game is such that the game's local action cannot proceed until it synchronizes with one or more remote game systems, then the latency of the Internet and/or LAN will accordingly delay the responsiveness of a game system. Although such systems may only require very low throughput (e.g. messages of game controller
Game controller
A game controller is a device used with games or entertainment systems used to control a playable character or object, or otherwise provide input in a computer game. A controller is typically connected to a game console or computer by means of a wire, cord or nowadays, by means of wireless connection...
actions may be only a few kilobits per second), the latency of the Internet and/or LAN must be low enough to meet the requirements of the game.
The maximum acceptable latency is game-type dependent. For example, generally, twitch gameplay games such as a first-person shooter
First-person shooter
First-person shooter is a video game genre that centers the gameplay on gun and projectile weapon-based combat through first-person perspective; i.e., the player experiences the action through the eyes of a protagonist. Generally speaking, the first-person shooter shares common traits with other...
like Quake 3 require lower latency for the best experience, while generally, a turn-based game such as chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
can tolerate higher latency. But, it entirely depends on the specifics of each game. For example, fast chess is a turn-based game that may have low latency requirements. And, in the case of twitch games, some games can be designed such that only events that impact the outcome of the game are subject to synchronization latency, allowing for fast local response time most of the time.
Cloud gaming
Cloud gaming
Cloud gaming, also called gaming on demand, is a type of online gaming that allows direct and on-demand streaming of games onto a computer, similar to video on demand, through the use of a thin client, in which the actual game is stored on the operator's or game company's server and is streamed...
is a type of online gaming where the entire game is hosted on a game server in a data center, and the user is only running a thin client
Thin client
A thin client is a computer or a computer program which depends heavily on some other computer to fulfill its traditional computational roles. This stands in contrast to the traditional fat client, a computer designed to take on these roles by itself...
locally that forwards game controller
Game controller
A game controller is a device used with games or entertainment systems used to control a playable character or object, or otherwise provide input in a computer game. A controller is typically connected to a game console or computer by means of a wire, cord or nowadays, by means of wireless connection...
upstream to the game server. The game server then renders the next frame of the game video which is compressed using low-latency video compression and is sent downstream and decompressed by the thin client. For the cloud gaming experience to be acceptable, the round-trip latency of all elements of the cloud gaming system (the thin client, the Internet and/or LAN connection the game server, the game execution on the game server, the video and audio compression and decompression, and the display of the video on a display device
Display device
A display device is an output device for presentation of information in visual or tactile form...
) must be low enough that the user perception is that the game is running locally. Because of such tight latency requirements, distance considerations of the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
through optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
come into play, currently limiting the distance between a user and a cloud gaming game server to approximately 1000 miles, according to OnLive
OnLive
OnLive is a cloud gaming platform: the games are synchronized, rendered, and stored on remote servers and delivered via the Internet.The service is available using the OnLive Game System, PCs running Microsoft Windows and Intel-based Macs with OS X 10.5.8 or later...
, the only company thus far operating a cloud gaming service.
Online game systems utilizing a wireless network
Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...
may be subject to significant latency, depending on the architecture of the wireless network and local electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
impacting that network. Although radio propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
through air is faster than light through optical fiber, wireless systems are often shared among many users and may suffer from latency incurred due to network congestion
Network congestion
In data networking and queueing theory, network congestion occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queueing delay, packet loss or the blocking of new connections...
which can trigger bufferbloat
Bufferbloat
Bufferbloat is a phenomenon in a packet-switched computer network whereby excess buffering of packets inside the network causes high latency and jitter, as well as reducing the overall network throughput...
related issues, or due to network protocols that introduce latency. And, in the event of electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
, transmitted packets may be lost, requiring a retransmission which also incurs latency.
See also
- Bandwidth-delay productBandwidth-delay productIn data communications, bandwidth-delay product refers to the product of a data link's capacity and its end-to-end delay . The result, an amount of data measured in bits , is equivalent to the maximum amount of data on the network circuit at any given time, i.e. data that has been transmitted but...
- BitrateBitrateIn telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
- Digital bandwidth
- GoodputGoodputIn computer networks, goodput is the application level throughput, i.e. the number of useful information bits, delivered by the network to a certain destination, per unit of time. The amount of data considered excludes protocol overhead bits as well as retransmitted data packets...
- Grade of serviceGrade of serviceIn telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service and the quality of service ....
- Ideal Web response time
- LagLagLag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
- Measuring network throughputMeasuring network throughputThroughput of a network can be measured using various tools available on different platforms. This page explains the theory behind what these tools set out to measure and the issues regarding these measurements.-Reasons for measuring throughput in networks:...
- Network traffic measurementNetwork traffic measurementIn computer networks, network traffic measurement is the process of measuring the amount and type of traffic on a particular network. This is especially important with regard to effective bandwidth management.- Tools :...
- Response timeResponse timeIn technology, response time is the time a system or functional unit takes to react to a given input.- Data processing :In data processing, the response time perceived by the end user is the interval between the instant at which an operator at a terminal enters a request for a response from a...