MPLS (Multi Protocol Label Switching) is a standards-approved technology for speeding up network traffic flow and making it easier to manage. MPLS is often referred to as the layer, in between the Data Link layer and Network layer, serving as a method to forward packets of data easily by using labels.
The MPLS forwards data that relates to both Layer 2 applications, such as Ethernet frames, and Layer 3 applications, such as IP packets. For this reason, it is often considered to be in between the two recognized layers.