Overview
A static Constraint-based Routed Label Switched Path (CRLSP) is established by manually specifying the incoming label, outgoing label, and required bandwidth on each node (ingress, transit, or egress node) of the forwarding path. If the device does not have enough bandwidth resources required by a CRLSP, the CRLSP cannot be established.
Static CRLSPs consume fewer resources, but they cannot automatically adapt to network topology changes. Therefore, static CRLSPs are suitable for small and stable networks with simple topologies.
Follow these guidelines to establish a static CRLSP:
On the ingress node, specify the outgoing label for the CRLSP, the next hop or the outgoing interface to the next hop, and the required bandwidth, create an MPLS TE tunnel interface, and reference the static CRLSP for the tunnel interface. The tunnel interface adds the outgoing label of the static CRLSP to each packet, and forwards the packet to the next hop or out of the outgoing interface.
A transit node swaps the label carried in a received packet with a specific label, and forwards the packet to the next hop or out of the outgoing interface. You must specify the incoming label, the outgoing label, the next hop or the outgoing interface, and the required bandwidth on each transit node.
If it is not configured with the penultimate hop popping function, an egress node pops the incoming label of a packet, and performs label forwarding according to the inner label or IP forwarding. You are only required to specify the incoming label on the egress node.
The outgoing label specified on an LSR must be the same as the incoming label specified on the directly connected downstream LSR.