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 othernetwork nodes, packets are buffered and queued, resulting in variable delay and throughput, depending on the traffic load in the network.

              Ethernet, Fast Ethernet, FDDI and Token Ring often referred to as traditional LAN, and they are sharing media, sharing of bandwidth shared LAN. In order to increase bandwidth, often using a network router division, will be divided into a network of more than one paragraph, each of the networks have different sub-address, different broadcasting domain, to reduce conflicts on the network, increase network bandwidth. Micro-paragraph of the network can not meet the LAN extension and the new high-bandwidth network applications to the demand, it is said that “traditional local area network has come to an end.”
In recent years the exchange processes-LAN technology, to address shared by the LAN network inefficient and can not provide adequate network bandwidth and network expansion and a series of difficult issues. It fundamentally changed the structure of shared local area network, to solve the bandwidth bottleneck. At present, the exchange of Ethernet, token ring exchange, the exchange of FDDI and ATM, such as the exchange of local area networks, Ethernet one of the most extensive exchange. LAN exchange has become the mainstream LAN technology.

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-switched network is the circuit-switched networks and packet switching network after a new exchange network, which mainly used for data communications. Packet switching is a store-and-forward of the exchange, it will at the user’s text is divided into a certain length of the packet to packet for store-and-forward, therefore, than the utilization of circuit-switched, than when the message exchange Extensions to small, but with real-time communication capabilities. Packet-switched TDM principle of the use of statistics, a data link multiplexing into multiple Luojixindao, eventually forming an Caller, Called party transmission of information between the access road, called the VC (VC) to achieve data Packet sent. Packet switching is used to optimize the use of the channel capacity available in digital telecommunication networks such as computer networks, to minimize the transmission latency (i.e. the time it takes for data to pass across the network), and to increase robustness of communication.

The most well-known use of packet switching is the Internet and local area networks. The Internet uses the Internet protocol suite over a variety of Link Layer protocols. For example, Ethernet and frame relay are very common. Newer mobile phone technologies (e.g., GPRS, I-mode) also use packet switching.

X.25 is a notable use of packet switching in that, despite being based on packet switching methods, it provided virtual circuits to the user. These virtual circuits carry variable-length packets. In 1978, X.25 was used to provide the first international and commercial packet switching network, the International Packet Switched Service (IPSS). Asynchronous Transfer Mode (ATM) also is a virtual circuit technology, which uses fixed-length cell relay connection oriented packet switching.

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