MPLS does not support IPv6 -- yet. Neither LDP nor MPLS Traffic Engineering (MPLS TE) interact with IPv6. To benefit from the MPLS features (for example, BGP-free network core, fast recovery with Fast Reroute or Traffic Engineering), you have to transport IPv6 across an MPLS-enabled IPv4 core. To offer public IPv6 services, you should use the 6PE technology (as described in RFC 4798, "Connecting IPv6 Islands over IPv4 MPLS Using IPv6 Provider Edge Routers"); if you want to offer IPv6 VPN services, use 6VPE technology (as described in RFC 4659).
This was first published in March 2010