RouterOS MPLS

MPLS forwards by labels instead of IP lookups. Because packets in the cloud are switched on labels, network-layer features (NAT, IP filtering) do not apply to them there: apply those at the ingress or egress router, ingress preferably. It is not supported on SMIPS devices (hAP lite, hAP lite TC, hAP mini). Plan the design before configuring; the manual recommends solid MPLS knowledge before production use.

Prerequisites, then LDP

1. A loopback address on every router (a bridge without ports, commonly named lo), used as the LSR ID and LDP transport address.
2. IP reachability between loopbacks from an IGP (routeros-ospf or IS-IS in routeros-routing); LDP follows the routing table, so a labelled packet takes the path an unlabelled one would.
3. Enable LDP only on core-facing interfaces, not on customer-facing ones.