Usage Scenario
In the IGP multi-instance scenario, without the
mpls te cspf multi-instance shortest-path command, CSPF calculates the shortest path using TEDB information in the first area. If the shortest path is successfully calculated, it is used to establish an LSP even if another shortest path exists in another area. The
mpls te cspf multi-instance shortest-path command enables CSPF to calculate the shortest path among all IGP processes and areas.
- If multiple reachable paths have the same weights, CSPF calculates the shortest path using TEDB information of the preferred IGP process or area (OSPF).
- If preferred-igp is used, CSPF can be configured to use TEDB information in a specified preferred IGP process or area. If no shortest path is found, CSPF uses TEDB information in another IGP process or area to calculate the shortest path.
Configuration Impact
This command is mutually exclusive with the mpls te cspf preferred-igp command.
Precautions
This command applies to P2P tunnels, not P2MP tunnels.
The disjoint algorithm in isolated LSP computation computes isolated primary and hot-standby LSPs, which may cause a failure to obtain the shortest path.