Configuring MPLS LDP inside SP Core


  • CEF must be enabled – without CEF the MPLS just doesnt work
  • IGP routing – for router to be able to map label to network the route must exist in routing table for that network. Router build from routing table the FIB in CEF and once you configure label binding it will configure also the LFIB based on that FIB
  • There is more common to use OSPF or ISIS as IGP in MPLS because these protocols support TE.

Basic config

  • #mpls label protocol ldp – ensure you use LDP for label distribution
  • #mpls ldp router-id loopback 0 – if you are using loopback as router id you have to advertise also loopback interfaces via IGP. The concept of router-id in MPLS is exactly the same like in OSPF, but the router-id must be reachable end-to-end! Only then routers will form LDP neighborship.
  • #mpls label range {range number} – routers assign random labels to networks and they are locally significant. If you want to make some system there you can use this command and specify what range should MPLS use for label binding.
  • under interface configuration you put # mpls ip
  • #show mpls ldp neighbor
  • #show mpls interfaces