Packet switching is a network communications method that groups all
transmitted data, irrespective of content, type, or structure into
suitably-sized blocks, called packets. The network over which packets
are transmitted is a shared network which routes each packet
independently from all others and allocates transmission resources as
needed. The principal goals of packet switching are to optimize
utilization of available link capacity and to increase the robustness
of communication. When traversing network adapters, switches and other
network nodes, packets are buffered and queued, resulting in variable
delay and throughput, depending on the traffic load in the network.
Network resources are managed by statistical multiplexing or
dynamic bandwidth allocation in which a physical communication channel
is effectively divided into an arbitrary number of logical
variable-bit-rate channels or data streams. Each logical stream
consists of a sequence of packets, which normally are forwarded by a
network node asynchronously using first-in, first-out buffering.
Alternatively, the packets may be forwarded according to some
scheduling discipline for fair queuing or for differentiated or
guaranteed quality of service, such as pipeline forwarding or
time-driven priority (TDP). Any buffering introduces varying latency
and throughput in transmission. In case of a shared physical medium,
the packets may be delivered according to some packet-mode multiple
access scheme.
Packet switching contrasts with another principal networking
paradigm, circuit switching, a method which sets up a specific circuit
with a limited number dedicated connection of constant bit rate and
constant delay between nodes for exclusive use during the communication
session.
Packet mode (or packet-oriented, packet-based) communication may
be utilized with or without intermediate forwarding nodes (packet
switches).
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