With the RSVP-TE LSP feature, the TE-DB only populates OSPFv2 local and remote TE-enabled links. A TE-link is a link that has one or more TE attributes added to it in the MPLS interface context. Link TE attributes are TE metric, bandwidth, and membership in a SRLG or an Admin-Group.
The SR-TE LSP path computation supports using SR-enabled links which may or may not have TE attributes and therefore the TE-DB is enhanced with, the following changes:
OSPFv2 is modified to pass all links, regardless if they are TE-enabled or SR-enabled, to TE-DB as currently performed by IS-IS.
TE-DB relaxes the link back-check when performing a CSPF calculation to ensure that there is at least one link from the remote router to the local router. Because OSPFv2 advertises the remote link IP address or remote link identifier only when a link is TE-enabled, the strict check about the reverse direction of a TE-link cannot be performed if the link is SR-enabled but not TE-enabled.
As a consequence of this change, CSPF can compute an SR-TE LSP with SR-enabled links that do not have TE attributes. This means that if the user admin shuts down an interface in MPLS, an SR-TE LSP path which uses this interface does not go operationally down.