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packet switching In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consi ...
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 Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
to a destination, which may be another host, a multicast group, or a
broadcast Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...
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: *
Processing delay In a network based on packet switching, processing delay is the time it takes routers to process the packet header. Processing delay is a key component in network delay. During processing of a packet, routers may check for bit-level errors in t ...
(the time taken to process a packet in a network node) *
Queuing delay In telecommunications and computer engineering, the queuing 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 completion of si ...
(the time a packet waits in a queue until it can be transmitted) * Transmission delay (the amount of time necessary to push all the packet into the wire) *
Propagation delay Propagation delay is the time duration taken for a signal to reach its destination, for example in the electromagnetic field, a wire, speed of sound, gas, fluid or seismic wave, solid body. Physics * An electromagnetic wave travelling through ...
(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, routers and network adapters, to achieve traffic shaping, policing, 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 first established across the network between two endpoints. The network, rather than having a fixed data rate reser ...
, also known as a virtual connection 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 Octet (computing), 8-bit quantity, and so the term octet stream is sometimes used interchangeab ...
. In packet switches, the flow may be identified by IEEE 802.1Q Virtual LAN tagging in Ethernet networks, or by a label-switched path in MPLS tag switching. Packet flow can be represented as a path in a network to model network performance. For example, a water flow network can be used to conceptualize packet flow.
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 infor ...
s 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

* Argus – Audit Record Generation and Utilization System * Cisco NetFlow * Dataflow (software engineering) * Data stream * Flow control * IP Flow Information Export *
Stream (computing) In computer science, a stream is a sequence of potentially unlimited 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 processe ...
*
Telecommunication circuit A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved from generally being built on physical connections between individual hardware cables, as in an analog phone switch, to v ...
* Traffic generation model


References

{{reflist Inter-process communication Streaming Packets (information technology) Computer networking