MPLS labels may be inserted in IPv6 source or destination IP address fields, potentially reducing network overhead bandwidth. In one implementation, a network device may receive a packet; determine whether the packet is an ingress packet for a MPLS LSP; determine an MPLS label for the packet when the packet is an ingress packet; insert the MPLS label in a portion of a source IP address field or a destination IP address field of the packet, when the packet is an ingress packet; and output the packet to the LSP.