Packet switching

The packet switching (English packet switching ) is a method of data transmission in computer networks. Longer messages are divided into individual packets and either connectionless ( datagram switching device ) or connection-oriented (virtual circuit switching ) transmitted.

Each package contains:

Source of the packet
Destination of the packet
Length of the data part
Packet sequence number
Classification of the packet

With packet switching, the packets traverse considered independent and separate units, the network and can be cached in the switching nodes. This is a significant advantage because now the transmission rate between the individual links is no longer a limitation. However, the architecture appears as a network of queues. Each must be passed node receives the packet and forwards it to its output interface ( the network node ) that can be the target of many programs but so that the tendency to overload situations arises. The existence of the queue generates one hand, delays in packet delivery or packet losses, which have a Retransmission and thus a further load on the transmission path result. For the user, this process is not transparent. It requires and receives no information on the routing. As a rule, he can not obtain this information, as we are changing transmission paths dynamically.

The system was developed by the British IT pioneer Donald Watts Davies and Leonard Kleinrock in the U.S..

Examples for packet switching are the Internet or newer mobile networks using standards such as UMTS.

Benefits

Compared to the line switching the packet switching has a number of advantages.

Because the individual packages are very small, the waiting times remain short for all participants and the network is well utilized.
The resources are ' fairly ' distributed to all participants. (see net neutrality )
Because of the small packets transmission errors can be quickly identified and corrected if necessary.
There is a high failure safety: falls from a switching station, the data stream is simply redirected.

Disadvantages

Since the transmission routes are not fixed, it can cause congestion at individual switching stations.
The packets do not arrive in the same order at the receiver, as they were sent (eg by different routing ).
All participants must use the same network protocols.
It can not be guaranteed constant bandwidth and can cause large swings.

Packet-switched networks

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