The SR-TE mesh LSP feature binds an SR-TE mesh P2P LSP template with one or more prefix lists. When the TE database discovers a router that has an ID matching an entry in the prefix list, it triggers MPLS to instantiate an SR-TE LSP to the router using the LSP parameters in the LSP template.
The SR-TE one-hop LSP feature activates an SR-TE one-hop P2P LSP template. In this case, the TE database tracks each TE link that is made to a directly connected IGP neighbor. It then instructs MPLS to instantiate an SR-TE LSP with the following parameters:
the source address of the local router
an outgoing interface matching the interface index of the TE-link
a destination address matching the router ID of the neighbor on the TE link
In both these types of SR-TE auto-LSPs, the router’s hop-to-label translation or local CSPF computes the label stack required to instantiate the LSP path.
The SR-TE on-demand LSP feature creates an LSP using an SR-TE on-demand P2P LSP template. When an imported BGP route matches an entry in a policy statement with an MPLS create tunnel action, an LSP is created to the next hop for the route. If a route admin tag policy is applied when the route is imported, only an auto-LSP with a template containing a matching admin-tag is created. The SR-TE on-demand LSP supports path computation using hop-to-label translation, local-CSPF, or a PCE.