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Understanding Label-Switched Paths on the NorthStar Controller


The NorthStar Controller uses PCEP to learn about LSPs in the discovered network topology, and all LSPs and their attributes can be viewed from the NorthStar Controller user interface. However, the LSP type determines whether the Path Computation Client (PCC) or NorthStar Controller maintains the operational and configuration states.

The following LSP types are supported on the NorthStar Controller:

  • Router-controlled LSP: The LSP is configured locally on the router, and the router maintains both the operational state and configuration state of the LSP. The NorthStar Controller learns these LSPs for the purpose of visualization and comprehensive path computation, but cannot change any attribute on these LSPs.

  • Delegated LSP: The LSP is provisioned on the PCC (router) and has been delegated to the NorthStar Controller for subsequent management. The operational state and configuration state of the LSP is stored in the PCC. For delegated LSPs, the ERO, bandwidth, LSP metric, and priority fields can be changed from the Northstar Controller user interface. However, the NorthStar Controller can return delegation back to the PCC, in which case, the LSP is reclassified as router controlled.

  • Controller-initiated LSP: The LSP is provisioned from the NorthStar Controller UI. For these LSPs, only the operational state is maintained in the router, and only NorthStar can update the LSP attributes.

The NorthStar Controller supports the discovery, control, and creation of protection LSPs (standby and secondary LSPs). For protection LSPs, the primary, secondary, and standby LSP must be of the same type (router-controlled, delegated, or controller-initiated). Each LSP can have its own specific bandwidth, setup priority, and hold priority or can use the values of the primary LSP (the default). A primary LSP must always be present for controller-initiated LSPs.