Queuing delay
Encyclopedia
In telecommunication
and computer engineering
, the queuing delay (or queueing delay) is the time a job waits in a queue until it can be executed. It is a key component of network delay
.
This term is most often used in reference to routers. When packets arrive at a router, they have to be processed and transmitted. A router can only process one packet at a time. If packets arrive faster than the router can process them (such as in a burst transmission
) the router puts them into the queue (also called the buffer
) until it can get around to transmitting them.
The maximum queuing delay is proportional to buffer size. The longer the line of packets waiting to be transmitted, the longer the average waiting time is. However, this is much preferable to a shorter buffer, which would result in ignored ("dropped") packets, which in turn would result in much longer overall transmission times.
During network congestion
, queuing delays can be considered infinite when the packet is dropped. The retransmission of such packets causes significant overall delay because all forms of delay will be incurred more than once. If the network congestion continues, the packet may be dropped many times. Many protocols, such as TCP
, will "throttle back" their sending and wait for the network to clear up.
In Kendall's notation
, the M/M/1/K queuing model, where K is the size of the buffer, may be used to analyze the queuing delay in a specific system. Check.
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
and computer engineering
Computer engineering
Computer engineering, also called computer systems engineering, is a discipline that integrates several fields of electrical engineering and computer science required to develop computer systems. Computer engineers usually have training in electronic engineering, software design, and...
, the queuing delay (or queueing delay) is the time a job waits in a queue until it can be executed. It is a key component of network delay
Network delay
Network delay is an important design and performance characteristic of a computer network or telecommunications network. The delay of a network specifies how long it takes for a bit of data to travel across the network from one node or endpoint to another. It is typically measured in multiples or...
.
This term is most often used in reference to routers. When packets arrive at a router, they have to be processed and transmitted. A router can only process one packet at a time. If packets arrive faster than the router can process them (such as in a burst transmission
Burst transmission
In telecommunication, the term burst transmission or data burst has the following meanings:# Any relatively high-bandwidth transmission over a short period of time...
) the router puts them into the queue (also called the buffer
Buffer (computer science)
In computer science, a buffer is a region of a physical memory storage used to temporarily hold data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device or just before it is sent to an output device...
) until it can get around to transmitting them.
The maximum queuing delay is proportional to buffer size. The longer the line of packets waiting to be transmitted, the longer the average waiting time is. However, this is much preferable to a shorter buffer, which would result in ignored ("dropped") packets, which in turn would result in much longer overall transmission times.
During 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...
, queuing delays can be considered infinite when the packet is dropped. The retransmission of such packets causes significant overall delay because all forms of delay will be incurred more than once. If the network congestion continues, the packet may be dropped many times. Many protocols, such as TCP
Transmission 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...
, will "throttle back" their sending and wait for the network to clear up.
In Kendall's notation
Kendall's notation
In queueing theory, Kendall's notation is the standard system used to describe and classify the queueing model that a queueing system corresponds to. First suggested by D. G...
, the M/M/1/K queuing model, where K is the size of the buffer, may be used to analyze the queuing delay in a specific system. Check.