MPLS TE basic concepts

CRLSP—Constraint-based Routed Label Switched Path. To establish a CRLSP, you must configure routing (as you do for a normal LSP), and specify constrains, such as explicit paths.

MPLS TE tunnel—A virtual point-to-point connection from the ingress node to the egress node. Typically, an MPLS TE tunnel consists of one CRLSP. To deploy CRLSP backup or fast reroute, or transmit traffic over multiple paths, you need to establish multiple CRLSPs for one class of traffic. In this case, an MPLS TE tunnel consists of a set of CRLSPs. An MPLS TE tunnel is identified by an MPLS TE tunnel interface on the ingress node. When the outgoing interface of a traffic flow is an MPLS TE tunnel interface, the traffic flow is forwarded through the CRLSP of the MPLS TE tunnel.