SDP is enhanced to use BGP route tunnel to extend inter-AS support for routes and services. An SDP can be configured based on service transport method (for example, GRE or MPLS tunnel). MPLS SDP support is enhanced to allow a BGP route tunnel to reach the far-end PE.
A single method of tunneling is allowed per SDP (for example, LDP, RSVP-TE LSP or BGP route tunnel).
For the inter-AS far-end PE, next-hop for BGP route tunnel must be one of the local ASBR. The LSP type selected to reach the local ASBR (BGP labeled route next-hop) must be configured under the BGP global context. LDP must be supported to provide transport LSP to reach the BGP route tunnel next-hop.
Only BGP route labels can be used to transition from ASBR to the next-hop ASBR. The global BGP route tunnel transport configuration option must be entered to select an LSP to reach the PE node from ASBR node. On the last BGP segment, both BGP and LDP and LDP routes may be available to reach the far-end PE from the ASBR node. LDP LSP must be preferred because of higher protocol priority. This leads to just one label besides other labels in stack to identify VC or VPN at far-end PE nodes.