Paste show mpls forwarding-table or trace output to visualize the label stack at each hop.
| Operation | Description | Forwarding Entry |
|---|---|---|
| PUSH | Add a new label to the top of the stack (ingress LER) | IP → label |
| SWAP | Replace top label with a new label (transit LSR) | label_in → label_out |
| POP | Remove top label and forward using remaining stack or IP | Pop Label |
| PHP | Penultimate Hop Popping — second-to-last router pops label to reduce egress LER work | Outgoing: Pop Label at penultimate hop |