When using constraints to determine a path for an LSP, the device takes into account information included in IS-IS LSPs with TE extensions. This information can be used to set up a path for a new LSP or to preempt an existing LSP so that an LSP with a higher priority can be established.
IS-IS LSPs with TE extensions include Type/Length/Value triplets (TLVs) containing the following information:
. When configured to do so with the traffic-engineering isis command, the device sends out IS-IS LSPs containing this TE information for each of its MPLS-enabled interfaces. Optionally, the user can specify the maximum amount of bandwidth that can be reserved on an interface. In addition, the user can assign interfaces to administrative groups.