Label Switching

When label switching, we describe a method for optimizing the data transfer in computer networks. Enables the overhead of the transmission of data from the conventional routing ( layer 3 of the OSI model ) to a pure switching ( layer 2 ), to be reduced. Therefore, the processing overhead for the routers involved falls sharply, creating a much lower processing time and shipping time is possible. Even so, costs can be saved.

Path setup

In large computer networks, such as the Internet, the data from sender to receiver are usually routed. This means that the devices involved in the transport, the so-called router must again determine in each data packet, how to deal with this. Routers often have many different communication partners ( other routers ) and manage a list, in the specified destination addresses are assigned to particular remote sites. Therefore Routers scan of each data packet, the destination and often the return address and use this data to determine the next target. This process is time-consuming.

When label switching a logical path is established before the actual data transmission by means of a signaling protocol. All network components involved in this path can be programmed to carry a specific label. Compares this process with the dial a phone number that precedes a call. The path can no longer change. After the end of the connection being reduced.

Switching the Labels

In the actual data transmission, equipped with label frames are only geswitchet. A label can be thought of as a coloring of a data packet. The power supplies route the data packets only to its label to the next device in the path. Delay times in the network devices are small compared to the routing. The load on the hardware with maintenance of routing tables is eliminated. This label switched networks are ideal for high-speed tasks. Because of the special units, the complex configuration and the low penetration of this technology in early 2006 is still expensive. Another disadvantage is the high susceptibility to failure. If one line or a device on the path, the fault is not even noticed in the worst case. Routed networks more responsive to interruptions.

Realization

Usually a label is inserted between the header of the link layer and the header of the network layer, the connection identifier is a short fixed length, similar to the VPI / VCI identifiers in ATM.

Label switching is investigated in the framework of the VIOLA project with other network technologies for their suitability in high speed portion.

An example of an implementation of label switching is the Multiprotocol Label Switching.