Besides the traffic engineering application, the RSVP-Tunnel specification may have other uses within the Internet. This applicability statement concerns only the use of RSVP to set up unicast LSP-tunnels. Aspects related to the support of other features and capabilities of RSVP by an implementation that also supports LSP-tunnels are beyond the scope of this document. However, support of such additional features and capabilities should not introduce new security vulnerabilities in environments that only use RSVP to set up LSP-tunnels. This applicability statement does not preclude the use of other signaling and label distribution protocols for the traffic engineering application in MPLS based IP networks.
Service providers are free to deploy whatever signaling protocol that meets their needs.
New error messages are defined to provide notification of exception conditions. This way, labels are allocated sequentially all the way from the egress node of the LSP-tunnel to the origination node. It is when the Resv message reaches the origination node that the LSP-tunnel becomes established. 3.0 Applicability of Extensions to RSVP for LSP Tunnels Use of RSVP-Tunnel is appropriate in contexts where it is useful to establish and maintain explicit label switched paths in an MPLS network. They may also be instantiated for other administrative reasons.