Frame relay is one of the most common WAN services in the United States. Frame relay will discard packets with errors, but cannot perform error control. Multiprotocol Label switching (MPLS) is another WAN technology that is designed to work with layer-2 protocols. Often referred as a layer-2.5 technology because it inserts 4-byte headers between layer-2 frame and layer-3 IP packet. MPLS works by having the customer connect to a common carrier network using a common layer-2 service. The carrier switch examines incoming frames and converts them in layer 2 or layer 3 addresses with a MPLS address label. Ethernet and IP in the LAN and BN environments are widely used by organizations today.