MPLS / GMPLS

Multi Protocol Label Switching (MPLS) is a protocol that makes it possible to provide virtual circuits through an IP network. This means that all the traffic from a specific source to its destination will all follow the same route. To do so, each packet gets a virtual circuit number, called a label. The label determines the packets queuing and forwarding through the network. A virtual circuit is called a Label Switched Path (LSP). A LSP has to be set up before use.

GMPLS and MPλS
The principle underlying this technology can also be applied to other transport networks. Generalized MPLS (GMPLS) extends MPLS to a suit of protocols which implements the same principal for other networks, such as networks that are based on SDH or optical networks. In an optical network, it are not virtual connections, but real connections, so-called lightpaths or tunnels, that are set up through the network. The version of MPLS used to switch a lightpath is called MPλS.

GMPLS makes it possible to implement intelligent services such as ASON (Automatically Switched Optical Networks) or ASTN (Automatically Switched Transport Networks).