Reset LSP Considerations

The clear mpls lsp command resets and restarts an MPLS RSVP LSP.

Note

These commands are disruptive. Data traffic forwarding is impacted as the LSP is not in active state for sub-seconds after teardown. Resetting an LSP could trigger a series of actions depending upon the current state of the LSP.

The following describes the actions and state changes when an LSP is reset.

Resetting an LSP also resets the associated backup/detour LSPs:

• Resetting the primary path of an LSP causes the secondary LSP path to become active, when a hot-standby secondary path for the LSP is available. However, when the primary path comes up after the reset operation, the active path switches over from the secondary to the primary again. When the "revert-timer" is configured, the LSP path switchover may be dampened and obeys the usual revert-timer rule. There is no change in the revert-timer behavior due to the reset LSP feature.

Note

The above state changes are described here for informational purposes only. There could be several other intermediate state changes that are not listed here.

• Resetting the primary path of an adaptive LSP also resets the "other" new instances of the LSPs primary path, when available at the time of reset.
• Resetting the secondary path for an LSP resets the current secondary path of the LSP. It also resets the selected secondary path, when available at the time of reset.
• Resetting the secondary path for an LSP whose primary path is down may trigger the secondary path selection process to choose a new secondary path. When a new secondary path is found, it is signaled and may become the active path. When no secondary paths are found, then the current secondary may become the active path again after successful RSVP signaling.
• The primary path is UP but not active, and the secondary path is UP and active. The secondary to primary switchover occurred because the revert-timer has been configured (using a large value). Resetting the secondary LSP path still forces the path switchover from secondary to primary path in spite of the revert-timer configuration.
• For an adaptive LSP, when reset is performed before the commit command, then the LSP is reset and comes-up with a new set of configuration parameters. However, this is disruptive for data traffic, unlike the commit command, because the current instance of the LSP is reset while there is no new instance of the LSP available (because the commit command has not been executed yet).