 Now, therefore, the main application of MPLS is to implement limited traffic engineering and layer 3 / layer 2 “service provider type” VPNs over IPv4 networks.Besides GMPLS, the main competitors to MPLS are Shortest Path Bridging (SPB), Provider Backbone Bridges (PBB), and MPLS-TP.These also provide services such as service provider layer 2 and layer 3 VPNs.