Computer Packets

The packets have a data buffer of medium size, which is sent as a unit via different shared set of links. The concept of packages and packet switching was first introduced by Paul Baran in 1962. Barans greatest concern was the survival of the network in the case of node failure; Existing transfer protocol centers are weak in central failures. In 1964, Donald Davies independently developed many of the same concepts; it is Davies who has made the word "package".

Perhaps it is worth noting that packets are buffers built with 8-bit bytes, and all hardware is what a byte is. The 8-bit byte is now universal, but that is not always the case. Perhaps the last large non-byte-oriented hardware platform, which in fact exceeds the broad definition of the Internet, is the DEC-10, with a 36-bit word size; a word can contain five 7-bit ASCII characters. On the LAN layer, packets can be considered as imposing a buffer structure above the low-level serial line; Additional layers require an extra structure. Not formally, packages are often called frames in the LAN layer and as segments in the transport layer. The maximum packet size supported by a particular LAN (eg Ethernet, Token Ring or ATM) is a real feature of that LAN. Ethernet offers a maximum of 1500 bytes of data. By comparison, TCP / IP packets typically contain only 512 bytes of data, while early Token Ring packets can hold up to 4 KB of data. Although there are proponents of very large packet sizes, larger than 64 KB, with other intensive ATM (Asynchronous Transfer Mode) protocols use 48 bytes of data per packet, and there are good reasons to believe in moderate packet size. Generally each layer adds its own header. Ethernet headers are typically 14 bytes, IP header 20 bytes, and TCP headers of 20 bytes. If a TCP connection sends 512 bytes of data to each packet, the header is 10% of the total, a non-unreasonable overhead. For an ordinary Voice-over-IP option, packages contain 160 bytes of data and 54 bytes of headers, making the header approximately 25% of the total. However, compressing 160 bytes of audio may contain some of the data up to 20 bytes, which means that the headers are 73% of the total.

The first part of internet specifications is to introduce a term octet (an 8-bit byte) and requires the packets to be octet order; non-octet hosts must be converted. If required, packages must be preceded by a header with the delivery information. In the general case that the datagram forwarding is mentioned, the header contains the destination address; Headers in networks that use virtual circuit forwarding contain an identifier for the connection. Almost all networks today are based on the package, although we will be informed later of a number of "circuit-switch" options for voice telephony.