Enabling OSPF-TE LSAs for MPLS interfaces
Information related to traffic engineering is carried in OSPF traffic engineering (OSPF-TE) LSAs.
OSPF-TE LSAs have special extensions that contain information about an interface’s traffic engineering metric, bandwidth reservations, and administrative group memberships.
When an RSVP-enabled device receives an OSPF-TE LSA, it stores the traffic engineering information in its Traffic Engineering Database (TED). The device uses information in the TED when performing calculations to determine a path for an LSP.
By default, OSPF-TE LSAs are sent out for all of its MPLS-enabled interfaces.
Because information in the TED is used to make path selections using CSPF and information in the TED comes from OSPF-TE LSAs, you do not need to enable the device to send out OSPF-TE LSAs with TE extensions when you want CSPF to perform constraint-based path selection.