fix ipv4 subnet mask with manual allocation ebgp

[ccoueffe]

Related Issue(s)

Fixes missing SUBNET_TARGET_MASK in eBGP VXLAN fabric payload when manual_underlay_allocation is enabled.

Related Collection Role

• cisco.nac_dc_vxlan.dtc.create
• other — roles/dtc/common/templates/ndfc_fabric/ebgp_vxlan_fabric/general/

Related Data Model Element

• vxlan.underlay

Proposed Changes

The SUBNET_TARGET_MASK parameter was nested inside the manual_underlay_allocation == false guard in the eBGP fabric template. This meant that when using manual underlay allocation, the subnet mask was not sent to NDFC — causing fabric creation/update to use NDFC defaults instead of the user-defined value.

SUBNET_TARGET_MASK is required by NDFC regardless of whether IP allocation is manual or automatic — it defines the point-to-point link prefix length for the underlay. The only condition where it should be omitted is when IPv6 underlay is enabled (since IPv6 uses a different parameter).

Fix: Moved SUBNET_TARGET_MASK outside the manual_underlay_allocation guard, keeping only the enable_ipv6_underlay condition:

Condition	Before (broken)	After (fixed)
manual=false, ipv6=false	✅ Rendered	✅ Rendered
manual=true, ipv6=false	❌ Missing	✅ Rendered
manual=false, ipv6=true	❌ Omitted	❌ Omitted
manual=true, ipv6=true	❌ Omitted	❌ Omitted

Test Notes

Tested with eBGP VXLAN fabric using manual_underlay_allocation: true and subnet_mask: 30. Verified:

• SUBNET_TARGET_MASK: "30" now appears in the fabric payload ✅
• SUBNET_RANGE remains correctly omitted for manual allocation ✅
• IPv6 underlay correctly omits SUBNET_TARGET_MASK ✅

Cisco Nexus Dashboard Version

ND 4.1+

Checklist

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

[juburnet]

Approved.

[marehler]

Looks good to me.