When the LSP is enabled, RSVP signaling messages travel to each LSR along the calculated path, reserving resources and causing labels to be dynamically associated with interfaces.
Signaled LSPs are configured at the ingress LER only. When a packet is assigned to a signaled LSP, it follows a pre-established path from the LSPs ingress LER to its egress LER. This path can be one of the following:
- A path that traverses an explicitly specified set of MPLS routers.
- The IGP shortest path across the MPLS domain determined from local routing tables.
A traffic-engineered path calculated by the device using constraints such as bandwidth reservations, administrative groups, and network topology information.