scope:

The BSM/MPLS technical specifications extend and complement the existing BSM functional architecture ([1] to [3]) and the SI-SAP interface [4] to enable transport of MPLS signalling and data flows over a BSM network, in a way such that MPLS networks connected by different STs can communicate as if they were connected by standard terrestrial LSRs (label switched routers).

In this general scope, TS 102 856-1 [13] clarifies the main architectural issues, including operational scenarios and protocol stacks, and discusses how BSM-compliant STs can be designed and configured to address MPLS-specific tasks.

The present document, clarifies the signalling issues related to the use of MPLS in BSM systems, with a particular focus on the case when the LSR is completely integrated in an ST; in this case the ST still acts in a BSM-compliant manner over the satellite, but it also behaves as a classical LSR on its terrestrial interface to external networks.

The setup of multicast MPLS paths is considered out of scope.