Rules to be followed for planning TE explicit paths

Loose and strict explicit paths are usually used in TE path planning. When configuring an explicit path, you can define a node that traffic must pass through or a node that traffic must bypass. Parameter include means that an LSP must pass through a specified node. Parameter exclude means that an LSP cannot pass through a specified node. When configuring a strict explicit path, you must specify the next hop and ensure that the next hop is directly connected to its upstream node. A loose explicit path allows other nodes to exist between the source and sink. In the IP RAN solution, loose explicit paths are usually used to facilitate future node addition or deletion.
When planning an explicit path for an LSP, note the following rules:
1. The explicit path must not pass through the destination device. In other words, if you have specified a node that an explicit path must pass through, then the explicit path must pass through this node before reaching the sink.
2. The explicit path must not pass through a path twice.
3. Among multiple paths between two nodes that an LSP must pass through, the explicit path uses the one with the lowest IGP cost. If you do not specify any node for the explicit path to pass through, the explicit path uses the path with the lowest IGP cost between the source and sink.
4. When overlapping is enabled, the primary and secondary paths try their best to avoid sharing the same path, but may share the same node.
It is recommended that you use the outbound interface IP address of the source or sink for route restriction. If you want to exclude multiple paths from an LSP, specify the intermediate nodes that need to be excluded besides specifying the outbound interface IP address of the source or sink. When configuring explicit paths, you are also advised to configure overlapping, route re-optimization, and automatic hot-standby backup path computation.

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