The configuration in IGP shortcut feature configuration enables IGP shortcuts for resolving IGP routes, indirect next hop of static routes, and BGP next hop of BGP routes. The user can enable LDP FECs over IGP shortcuts by further configuring T-LDP sessions, with the tunneling option, to the destination of the RSVP LSP. In this case, LDP FEC is tunneled over the RSVP LSP, effectively implementing LDP-over-RSVP without having to enable the ldp-over-rsvp option in OSPF or IS-IS. The ldp-over-rsvp and igp-shortcut options are mutually exclusive under OSPF or IS-IS.
Similarly, LDP FECs can be tunneled over SR-TE LSPs as detailed in IPv4 IGP shortcuts using SR-TE LSP feature configuration.