An LSRs Traffic Engineering Database (TED) contains topology information about nodes in an MPLS domain and the links that connect them. This topology information is obtained from the IS-IS LSPs with traffic engineering extensions. IS-IS LSPs with TE extensions have special extensions that contain information about an MPLS-enabled interface‘s traffic engineering metric, bandwidth reservations, and administrative group memberships.
An LSR, when configured to do so, floods IS-IS LSPs with TE extensions for its MPLS-enabled interfaces to its neighboring routers in the IS-IS area. Other LSRs store the information from the IS-IS LSPs with TE extensions in their own Traffic Engineering Databases (TED ), allowing each LSR in the area to maintain an identical TED describing the MPLS topology. The topology information in the TED is used by the CSPF process when it calculates traffic-engineered paths for signaled LSPs.