hi,
recent linux kernel have mpls support included. frr builds in vyos have also mpls support included and the iproute2 on vyos is also mpls ready.
Documentation:
http://www.samrussell.nz/2015/12/mpls-testbed-on-ubuntu-linux-with.html
http://docs.frrouting.org/en/latest/zebra.html#mpls-commands
in 1.2.x frr raised an error cause the kernel is lacking mpls support...