First, you need to remember MPLS-Traffic engineering operation.
MPLS-traffic engineering requires four steps, as shown below, for its operation.
- Link information such as bandwidth, IGP metric, TE metric, and SRLG is flooded throughout the IGP domain by the link state protocols.
- The path is calculated either with CSPF in a distributed manner or with offline tools as a centralized fashion.
- If a suitable path is found, it is signalled via RSVP-TE and the RSVP assigns the label for the tunnels.
- The traffic is placed in the tunnels.