On the PE router. In this case r01.fr.dn42.dk

Lang: 
###
### r02.nl.dn42.dk - MPLS
###
auto tun-mpls-r02-nl

iface tun-mpls-r02-nl inet static
  address 10.0.254.23/31
  pre-up ip tun add $IFACE mode gre ttl 64 local 185.10.17.124 remote 193.148.248.222
  post-up sysctl net.mpls.conf.$IFACE.input=1
  post-down ip link del $IFACE

  iface tun-mpls-r02-nl inet6 static
  address fd45:3282:58e7:ff0a::2/64
  post-up ip addr add fe80::ff0a:2/64 dev $IFACE

On r02.nl.dn42.dk network configuration is:

Lang: 
###
### r01.fr.dn42.dk - MPLS
###
auto tun-mpls-r01-fr

iface tun-mpls-r01-fr inet static
  address 10.0.254.22/31
  pre-up ip tun add $IFACE mode gre ttl 64 remote 185.10.17.124 local 193.148.248.222
  post-up sysctl net.mpls.conf.$IFACE.input=1
  post-down ip link del $IFACE

  iface tun-mpls-r01-fr inet6 static
  address fd45:3282:58e7:ff0a::1/64
  post-up ip addr add fe80::ff0a:1/64 dev $IFACE