This feature is supported only on the 7210 SAS-Mxp, 7210 SAS-R6, and 7210 SAS-R12.
The config>router>mpls>bypass-resignal-timer command triggers the periodic global reoptimization of all dynamic bypass LSP paths associated with an RSVP P2P LSP. The operation is performed at each expiry of the user-configurable bypass LSP resignal timer.
When this command is enabled, MPLS requests the CSPF for the best path for each dynamic bypass LSP originated on this node. The constraints, hop limit, SRLG, and admin-group constraints of the first associated LSP primary path that originally triggered the signaling of the bypass LSP must be satisfied. To do this, MPLS saves the original Path State Block (PSB) of that LSP primary path, even if the latter is torn down.
If CSPF returns no path or returns a new path with a cost that is higher than the current path, MPLS does not signal the new bypass path. If CSPF returns a new path with a cost that is lower than the current path, MPLS signals it. Also, if the new bypass path is SRLG strict disjoint with the primary path of the original PSB while the current path is SRLG loose disjoint, the manual bypass path is resignaled, regardless of cost comparison.
After the new path is successfully signaled, MPLS evaluates each PSB of each PLR (that is, each unique avoid-node or avoid-link constraint) associated with the current bypass LSP path to check if the corresponding LSP primary path constraints are still satisfied by the new bypass LSP path. If so, the PSB association is moved to the new bypass LSP.
Each PSB for which the constraints are not satisfied remains associated with the PLR on the current bypass LSP and is checked at the next background PSB re-evaluation, or at the next timer or manual bypass reoptimization. Additionally, if SRLG FRR loose disjointness is configured using the configure>router>mpls srlg-frr command, and the current bypass LSP is SRLG disjoint with a primary path while the new bypass LSP is not SRLG disjoint, the PSB association is not moved.
If a specific PLR associated with a bypass LSP is active, the corresponding PSBs remain associated with the current PLR until the global revertive Make-Before-Break (MBB) tears down all corresponding primary paths, which also causes the current PLR to be removed.
While it is in the preceding state, the older PLR does not get any new PSB association until the PLR is removed. When the last PLR is removed, the older bypass LSP is torn down.
Additionally, PSBs that have not been moved by the dynamic or manual reoptimization of a bypass LSP as a result of the PSB constraints not being met by the new signaled bypass LSP path are re-evaluated by the FRR background task, which handles cases where the PSB has requested node protection, but its current PLR is a link-protect.
This feature is not supported with an inter-area dynamic bypass LSP and bypass LSP protecting S2L paths of a P2MP LSP.
The tools>perform>router>mpls>resignal-bypass command performs a manual reoptimization of a specific dynamic or manual bypass LSP, or of all dynamic bypass LSPs.
The user must configure the manual bypass LSP name. The dynamic bypass LSP name is displayed in the output of show>router>mpls>bypass-tunnel dynamic detail.
The delay option triggers the global reoptimization of all dynamic bypass LSPs at the expiry of the specified delay. This option forces the global bypass resignal timer to expire after an amount of time equal to the value of the delay parameter. This option has no effect on a manual bypass LSP.
However, when the bypass LSP name is specified, the named dynamic or manual bypass LSP is signaled and the associations are moved only if the new bypass LSP path has a lower cost than the current one. This behavior is different from that of the tools>perform>router>mpls>resignal command for the primary or secondary active path of an LSP, which signals and switches to the new path, regardless of the cost comparison. This handling is required because a bypass LSP can have a large number of PSB associations and the associated processing churn is much higher.
In the specific case where the name corresponds to a manual bypass LSP, the LSP is torn down and resignaled using the new path provided by CSPF if no PSB associations exist. If one or more PSB associations exist but no PLR is active, the tools>perform>router>mpls>resignal-bypass bypass-lsp-name configuration fails and the user is prompted to explicitly enter the force option. In this case, the manual bypass LSP is torn down and resignaled, temporarily leaving the associated LSP primary paths unprotected. If one or more PLRs associated with the manual bypass LSP is active, the command fails.
Finally, and as with the timer-based resignal, the PSB associations are checked for the SRLG and admin-group constraints using the updated information provided by CSPF for the current path and new path of the bypass LSP. See RSVP-TE bypass LSP path SRLG information update in manual and timer resignal MBB and RSVP-TE bypass LSP path administrative group information update in manual and timer resignal MBB for more information.