Fix for ANYCAST_RP_IP_RANGE on ND 3.1 for eBGP fabrics

[skaszlik]

[ND3.1.x] [eBGP fabric] ANYCAST_RP_IP_RANGE is not deploying on NDFC

Related Issue(s)

Fixes #688

Related Collection Role

• cisco.nac_dc_vxlan.validate
• cisco.nac_dc_vxlan.dtc.create
• [] cisco.nac_dc_vxlan.dtc.deploy
• cisco.nac_dc_vxlan.dtc.remove
• other

Related Data Model Element

• vxlan.fabric
• vxlan.global
• vxlan.topology
• vxlan.underlay
• vxlan.overlay
• vxlan.overlay_extensions
• vxlan.policy
• vxlan.multisite
• defaults.vxlan
• other

Proposed Changes

Test Notes

Cisco Nexus Dashboard Version

Checklist

• Latest commit is rebased from develop with merge conflicts resolved
• New or updates to documentation has been made accordingly
• Assigned the proper reviewers

[mkilar123]

seems fine

[juburnet]

🔍 Code Review Summary

Overall Assessment

This PR correctly fixes a critical bug where ANYCAST_RP_IP_RANGE was not being deployed on NDFC 3.1.x for eBGP fabrics with multicast replication mode. The fix relocates the conditional block to the proper location in the template hierarchy.

🟢 Positive Changes

1. Correct Fix: Moves ANYCAST_RP_IP_RANGE to align with the same pattern used in dc_vxlan_fabric_resources.j2
2. Proper Conditional Logic: Now correctly checks for:
   • NOT manual_underlay_allocation
   • NOT enable_ipv6_underlay
   • replication_mode == 'Multicast'
3. Consistency: Matches the established pattern in the OSP/ISIS fabric templates

🟡 Areas for Improvement

1. Missing Test Coverage: No automated tests to validate this template rendering scenario
2. Documentation: The PR description lacks detail about the root cause and testing performed
3. Trailing Whitespace: Lines 21 and 23 have trailing spaces that should be removed

🐛 Root Cause Analysis

Previous Bug: The ANYCAST_RP_IP_RANGE was nested inside a multicast-specific conditional block (lines 38-40 in old code) that was itself nested inside another IPv6 check. This caused it to be skipped when:

• enable_ipv6_underlay = false (IPv4 underlay)
• manual_underlay_allocation = false (auto allocation)
• replication_mode = Multicast

Fix: Moves the setting to lines 21-23, which is:

• Inside the NOT manual_underlay_allocation block
• Inside the NOT enable_ipv6_underlay block
• Directly after LOOPBACK1_IP_RANGE
• Only conditionally rendered when replication_mode == 'Multicast'

This matches the exact pattern used in dc_vxlan_fabric_resources.j2 (lines 8-10).

📊 Review Status

• Decision: APPROVE with minor suggestions
• Critical Issues: 0
• Warnings: 0
• Suggestions: 2 (trailing whitespace, test coverage)
• Code Quality: ✅ Good

🎯 Recommendations

1. Remove trailing whitespace on lines 21 and 23
2. Add test case to prevent regression (e.g., validate template rendering with multicast mode + auto allocation)
3. Update PR description with root cause analysis and test evidence

✅ Verification

The change is minimal (3 lines moved), logic is sound, and aligns with established patterns. Safe to merge after addressing trailing whitespace.

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Reviewed by: Claude Code (Sisyphus)
Review Date: 2026-02-02
Commit SHA: 93aa925

[juburnet]

@mtarking - I tested this before and after the fix for eBGP on ND 3.1.
The fix successfully sets the ANYCAST_RP_IP_RANGE condition with our fabric that meets the conditions:
enable_ipv6_underlay = false (IPv4 underlay)
manual_underlay_allocation = false (auto allocation)
replication_mode = Multicast

The conditions and placement in the jinja template function correctly.

Before it was failing to set the value and failing robot tests.
Before:

After:

[skaszlik]

Hi @mtarking ,

The current template (develop branch) include ENABLE_TRMv6 unconditionally under multicast. The fix wraps it with a version check (>= 12.2.2), since TRMv6 is only supported on NDFC 12.2.2+.

[juburnet]

Approved. ANYCAST_RP_IP_RANGE wasn't being set for ND 3.1 in the previous location because it was under a version requirement "if" statement. Tested working

[mkilar123]

lgtm