NewValidation: CSCwu34390 - Detect Fabric BFD enabled on IS-IS

[monrog2]

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Validation Type

[ ] - Fault

[x] - Config

[x] - Bug

[ ] - Other

What needs to be validated

Detect any L3 interface policy (l3IfPol) with Fabric BFD for IS-IS (bfdIsis) set to enabled before an upgrade or downgrade.

Authoritative defect: CSCwu34390.

Expected behavior

• Inspect all relevant L3 interface policies.
• Return FAIL_O and report every affected policy DN when Fabric BFD is enabled.
• Return PASS only when complete, successful collection confirms Fabric BFD is disabled.
• Do not return PASS when collection fails or is incomplete.
• Preserve malformed affected objects as unformatted evidence rather than discarding them.
• Recommend disabling Fabric BFD before proceeding with the upgrade or downgrade.
• Keep the validation applicable to maintenance targets without a target-version gate.

Why it needs to be validated

Fabric BFD can falsely flap during CPU pressure, affecting IS-IS adjacencies and potentially destabilizing the fabric control plane. Active Fabric BFD should be disabled before an upgrade or downgrade.

Testing requirements

Include Python 2.7 and Python 3.8 coverage for:

• Fabric BFD enabled.
• Fabric BFD disabled.
• Mixed enabled and disabled policies.
• Duplicate policy objects.
• Empty and partial inventory.
• Malformed policy objects.
• Mixed valid and malformed objects.
• APIC API errors.
• Complete Result output, including status, headers, string-normalized data, unformatted evidence, recommended action, and documentation URL.