H3C S9500 Series Operation Manual page 1007

Operation Manual – MPLS OAM
H3C S9500 Series Routing Switches
Execute the display mpls protect-switch [ all | protect-id ] verbose command. If
the Working LSP User Plane Status is No-defect, which means the primary LSP
configured in the protection group is not the one for OAM defect verification. In this
case, you should use OAM ingress node and egress node configuration
commands to configure OAM parameters for the primary LSP in the protection
group and restart defect verification, or use the protection group configuration
command to configure a protection group for the LSP for defect verification.
If the Working LSP User Plane Status field is In defect and the Protect LSP User
Plane Status field is In defect, which means the secondary LSP in the protection
group has defects. In this case, you should use the protection group command to
configure another perfect LSP and the primary LSP to constitute a protection
group.
If the above two conditions are not met, view the Holdoff field. If the Holdoff is not
zero, which means Holdoff does not expire. This is not a fault. When the primary
LSP fails, data flows are switched to the secondary LSP only when it is always
available after Holdoff time. To trigger protection switching immediately after the
primary LSP fails, you should use the protection group command to set Holdoff to
zero.
1.5.6 The Primary LSP Recovered from a Defect, but the Protection Group
cannot Switch back
I. Symptom
When you execute the display mpls protect-switch protect-id command, the Switch
Rst field is P. In this case, data flows are still transmitted over the secondary LSP, even
the primary LSP recovered from a defect.
II. Solution
The reason for this problem may come from:
The protection group is in non-revertive mode.
The switch back wait time is longer.
The external switching command switches data flows to the secondary LSP for
transmission by force. It has a higher priority.
To solve this problem, you can:
Execute the display mpls protect-switch [ protect-id | all ] verbose command. If
the Revertive Mode field is Non-revertive, the protection group is in non-revertive
mode. This is not a fault. To trigger switch back after the primary LSP recovered
from a defect, you should use the mpls protect-switch command to configure the
protection group as revertive mode.
If the protection group is in revertive mode and the WTR field is not zero, which
means WTR does not expire. This is not a fault. After the primary LSP recovered
from a defect, data flows will be switched back to the primary LSP in WTR time. To
Chapter 1 MPLS OAM Configuration
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