In
packet switching
In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the p ...
networks, traffic flow, packet flow or ''network flow'' is a sequence of
packets from a source
computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...
to a destination, which may be another host, a
multicast
In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused wi ...
group, or a
broadcast
Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...
domain. RFC 2722 defines traffic flow as "an artificial logical equivalent to a call or connection." RFC 3697 defines traffic flow as "a sequence of packets sent from a particular source to a particular unicast, anycast, or multicast destination that the source desires to label as a flow. A flow could consist of all packets in a specific transport connection or a media stream. However, a flow is not necessarily 1:1 mapped to a transport connection." Flow is also defined in RFC 3917 as "a set of IP packets passing an observation point in the network during a certain time interval."
Packet flow temporal efficiency can be affected by
one-way delay (OWD) that is described as a combination of the following components:
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Processing delay
Processing is a free graphical library and integrated development environment (IDE) built for the electronic arts, new media art, and visual design communities with the purpose of teaching non-programmers the fundamentals of computer programmin ...
(the time taken to process a packet in a network node)
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Queuing delay
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. In a switched network, queuing delay is the time between the ...
(the time a packet waits in a queue until it can be transmitted)
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Transmission delay
In a network based on packet switching, transmission delay (or store-and-forward delay, also known as packetization delay) is the amount of time required to push all the packet's bits into the wire. In other words, this is the delay caused by the ...
(the amount of time necessary to push all the packet into the wire)
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Propagation delay
Propagation delay is the time duration taken for a signal to reach its destination. It can relate to networking, electronics or physics. ''Hold time'' is the minimum interval required for the logic level to remain on the input after triggering ed ...
(amount of time it takes the signal’s header to travel from the sender to the receiver)
Utility for network administration
Packets from one flow need to be handled differently from others, by means of separate queues in
switches
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...
,
routers and
network adapters, to achieve
traffic shaping
Traffic shaping is a bandwidth management technique used on computer networks which delays some or all datagrams to bring them into compliance with a desired ''traffic profile''. Traffic shaping is used to optimize or guarantee performance, impro ...
,
fair queueing or
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 quantitat ...
. It is also a concept used in Queueing Network Analyzers (QNAs) or in packet tracing.
Applied to Internet
routers, a flow may be a host-to-host communication path, or a
socket-to-socket communication identified by a unique combination of source and destination addresses and port numbers, together with transport protocol (for example,
UDP or
TCP). In the TCP case, a flow may be a
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 established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
, also known as a
virtual connection
A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
or a
byte stream
A bitstream (or bit stream), also known as binary sequence, is a sequence of bits.
A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...
.
In packet switches, the flow may be identified by
IEEE 802.1Q Virtual LAN tagging in Ethernet networks, or by a
Label Switched Path
Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identif ...
in
MPLS
Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identif ...
tag switching.
Packet flow can be represented as a
path in a network to model network performance. For example, a water
flow network
In graph theory, a flow network (also known as a transportation network) is a directed graph where each edge has a capacity and each edge receives a flow. The amount of flow on an edge cannot exceed the capacity of the edge. Often in operations re ...
can be used to conceptualize packet flow. Channels can be thought of as pipes, with the pipe capacity corresponding to bandwidth and flows corresponding to data throughput. This visualization can help to understand bottlenecks, queuing, and the unique requirements of tailored systems.
See also
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Argus – Audit Record Generation and Utilization System Argus – the Audit Record Generation and Utilization System is the first implementation of network flow monitoring, and is an ongoing open source network flow monitor project. Started by Carter Bullard in 1984 at Georgia Tech, and developed for cy ...
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Cisco NetFlow
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Communication channel
A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for informa ...
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Dataflow
In computing, dataflow is a broad concept, which has various meanings depending on the application and context. In the context of software architecture, data flow relates to stream processing or reactive programming.
Software architecture
Da ...
(software engineering)
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Data stream
In connection-oriented communication, a data stream is the transmission of a sequence of digitally encoded coherent signals to convey information. Typically, the transmitted symbols are grouped into a series of packets.
Data streaming has b ...
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Flow control
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Traffic shaping
Traffic shaping is a bandwidth management technique used on computer networks which delays some or all datagrams to bring them into compliance with a desired ''traffic profile''. Traffic shaping is used to optimize or guarantee performance, impro ...
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Traffic policing (communications) In communications, traffic policing is the process of monitoring network traffic for compliance with a traffic contract and taking steps to enforce that contract. Traffic sources which are aware of a traffic contract may apply traffic shaping to ens ...
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Flow network
In graph theory, a flow network (also known as a transportation network) is a directed graph where each edge has a capacity and each edge receives a flow. The amount of flow on an edge cannot exceed the capacity of the edge. Often in operations re ...
in graph theory
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IP Flow Information Export
Internet Protocol Flow Information Export (IPFIX) is an IETF protocol, as well as the name of the IETF working group defining the protocol. It was created based on the need for a common, universal standard of export for Internet Protocol flow infor ...
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Path (graph theory)
In graph theory, a path in a graph is a finite or infinite sequence of edges which joins a sequence of vertices which, by most definitions, are all distinct (and since the vertices are distinct, so are the edges). A directed path (sometimes ...
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Stream (computing)
In computer science, a stream is a sequence of data elements made available over time. A stream can be thought of as items on a conveyor belt being processed one at a time rather than in large batches.
Streams are processed differently from ...
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Telecommunication circuit
A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved over time from generally being built on physical connections between individual hardware cables, as in an analog phone swi ...
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Traffic generation model
References
{{reflist
Inter-process communication
Streaming
Packets (information technology)
Computer networking