label switching (MPLS)

Label switching is an optimal combination of the best features of layer 2 switching and layer 3 routing. The concept of label switching is based on marking IP datagrams with labels and forwarding the datagrams to a modified switch or router, which in turn uses the label to route the datagrams through the network.

In label switching, the switching is based on the label, i.e., the packet identifier. Based on this label, the label switch decides on the route of the packet and its prioritization. Before leaving the switch, the label's numerical value is set to the value that the next switch expects to make the correct routing decision. Label switching is thus characterized by a preceding process that determines the sequence of values a label will have as it passes through the switches and determines which path the packet will take.

Label switching is used, among other things, in the label switching routers( LSR) in multi- protocol label switching( MPLS) to determine the label switched path( LSP). This technique allows data streams from different virtual private networks(VPNs) to be transmitted separately over the same core network.

The advantage of label switching is the higher efficiency in forwarding IP packets in contrast to hop-by-hop methods, where the forwarding for each individual packet is made by analyzing the header in the router.