Overview

A static label switched path (LSP) is established by manually specifying the incoming label and outgoing label on each node (ingress, transit, or egress node) of the forwarding path.

Static LSPs consume fewer resources, but they cannot automatically adapt to network topology changes. Therefore, static LSPs are suitable for small and stable networks with simple topologies.

Follow these guidelines to establish a static LSP:

• The ingress node determines an FEC for a packet according to the destination address, inserts the label for that FEC into the packet, and forwards the packet to the next hop or out of the outgoing interface. Therefore, on the ingress node, you must specify the outgoing label for the destination address (the FEC) and the next hop or 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. Therefore, on each transit node, you must specify the incoming label, the outgoing label, and the next hop or the outgoing interface.

• If the penultimate hop popping function is not configured, an egress node pops the incoming label of a packet, and performs label forwarding according to the inner label or IP forwarding. Therefore, on the egress node, you only need to specify the incoming label.

• The outgoing label specified on an LSR must be the same as the incoming label specified on the directly connected downstream LSR.