Nokia 7705 SAR-W Series Manual page 211

MPLS Guide
At the next opportunity (that is, when the primary path goes down), the LSP uses of an eligible
SRLG secondary path if the secondary path is in the up state. If all secondary eligible SRLG
paths are in the down state, MPLS/RSVP-TE uses a non-SRLG secondary path if the path is
configured and in the up state. If, while the LSP is using a non-SRLG secondary path, an
eligible SRLG secondary path comes back up, MPLS/RSVP-TE will not switch the path of the
LSP to it. As soon as the primary path is resignaled and comes up with a new SRLG list,
MPLS/RSVP-TE resignals the secondary path using the new SRLG list.
A secondary path that becomes ineligible as a result of an update to the SRLG membership
list of the primary path will have its ineligibility status removed when any of the following
events occurs:
Changes to SRLG Membership List
Once the primary path of the LSP is set up and is operationally up, any subsequent changes
to the SRLG membership of an interface that the primary path is using is not considered until
the next opportunity that the primary path is resignaled. The primary path may be resignaled
due to a failure or to a make-before-break operation. A make-before-break operation occurs
as a result of a global revertive operation, a timer-based or manual reoptimization of the LSP
path, or a change by the user to any of the path constraints.
Once an SRLG secondary path is set up and is operationally up, any subsequent changes to
the SRLG membership of an interface that the secondary path is using is not considered until
the next opportunity that the secondary path is resignaled. The secondary path is resignaled
due to a failure, to a resignaling of the primary path, or to a make-before-break operation. A
make-before-break operation occurs as a result of a timer-based or manual reoptimization of
the secondary path, or a change by the user to any of the path constraints of the secondary
path, including enabling or disabling the SRLG constraint itself.
In addition, any user-configured include or exclude admin group statements for this
secondary path are checked along with the SRLG constraints by CSPF.
The no form of the command reverts to the default value.
Default no srlg
3HE 18686 AAAB TQZZA
• A successful MBB operation of the standby SRLG path occurs, making it eligible again.
• The standby path goes down, in which case MPLS/RSVP-TE puts the standby on retry
when the retry timer expires. If successful, it becomes eligible. If not successful after the
retry timer expires or the number of retries reaches the configured retry-limit value, it is
left down.
• The primary path goes down, in which case the ineligible secondary path is immediately
torn down and will only be resignaled when the primary path comes back up with a new
SRLG list.
Use subject to Terms available at: www.nokia.com
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MPLS and RSVP-TE
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