[OSPF] Implement Advanced OSPF Support in Terraform Provider

[Dan-Dev-Net]

Related Issues

Fixes #507

Changes

Router-Level OSPF Attributes

Log Adjacency Changes:

• log_adjacency_changes - Log changes in adjacency state (choice option)
• log_adjacency_changes_detail - Log changes with detail (mutually exclusive with above)

NSF (Non-Stop Forwarding):

• nsf_cisco - Enable Cisco NSF (choice option)
• nsf_cisco_enforce_global - Enforce global NSF neighbors
• nsf_ietf - Enable IETF graceful restart (mutually exclusive with cisco)
• nsf_ietf_restart_interval - Restart interval in seconds (1-3600)

Max-Metric Router LSA:

• max_metric_router_lsa - Set maximum metric temporarily
• max_metric_router_lsa_summary_lsa_metric - Summary LSA metric (1-16777215)
• max_metric_router_lsa_external_lsa_metric - External LSA metric (1-16777215)
• max_metric_router_lsa_include_stub - Include stub networks
• max_metric_router_lsa_on_startup_time - Duration in seconds (5-86400)
• max_metric_router_lsa_on_startup_wait_for_bgp - Wait for BGP (mutually exclusive with time)

Fast-Reroute:

• fast_reroute_per_prefix_enable_prefix_priority - Priority of prefixes to protect (high/low)
  • Note: Requires network-advantage license
  • Note: Non-VRF only (not available in ospf_vrf resource)

Redistribute:

• redistribute_static_subnets - Redistribute static routes with subnets
• redistribute_connected_subnets - Redistribute connected routes with subnets

Interface-Level OSPF Attributes (1 attribute)

Multi-Area:

• multi_area_ids - List of additional OSPF area IDs for multi-homing
  • Supports both decimal (0-4294967295) and IPv4 address format

YANG Model Details

Choice Structures Handled

• log-adjacency-changes-choice - Base vs detail logging
• nsf-cisco-ietf - Cisco NSF vs IETF graceful restart
• time-wait-for-bgp-choice - Time-based vs BGP-triggered max-metric

Presence Containers

• nsf-cisco, nsf-ietf - Enabled when present
• router-lsa - Max-metric configuration container

Union Types

• area-id in multi-area - Accepts uint32 or ipv4-address

Version Compatibility

YANG Version Analysis Performed:

• ✅ All features verified to exist in IOS-XE 17.12.1 YANG model
• ✅ All features verified to exist in IOS-XE 17.15.1 YANG model
• ✅ No test_tags required - Features compatible with all pipeline test devices

Analysis documented in: EPIC-510-ospf_advanced_support/YANG-VERSION-COMPATIBILITY.md

Testing

Direct Provider Testing

• Provider build successful (make gen + go build)
• Terraform init/plan/apply successful
• Device configuration verified via CLI
• Idempotency confirmed (no changes on second apply)
• Terraform destroy successful

Device Testing Details

• Device: Cat8kv at 10.81.239.57
• IOS-XE Version: 17.15.1a
• License: network-advantage (required for fast-reroute)

Configuration Verified on Device

router ospf 100
 max-metric router-lsa include-stub summary-lsa 16711680 external-lsa 16711680 on-startup 60
 nsf cisco enforce global
 fast-reroute per-prefix enable prefix-priority high
 redistribute connected
 redistribute static
 log-adjacency-changes

Test Files (Not Committed)

• Local testing performed with test-ospf-epic510.tf
• Test files excluded from PR per project standards

Key Implementation Notes

VRF Limitations

• fast-reroute is not available in VRF OSPF per YANG model
• Only included in ospf.yaml, excluded from ospf_vrf.yaml
• Module implementation reflects this limitation

License Requirements

• fast-reroute requires network-advantage license
• Feature not visible on devices with network-essentials license
• Documented in testing results

Default Value Behavior

• log-adjacency-changes defaults to true in IOS-XE
• Appears in show run all but not in show run
• Provider correctly manages this default

Files Modified

Definition Files (3)

• gen/definitions/ospf.yaml - Added 17 router-level attributes
• gen/definitions/ospf_vrf.yaml - Added VRF-compatible attributes (no fast-reroute)
• gen/definitions/interface_ospf.yaml - Added multi-area support

Generated Files (24)

• Resource/Data source files for ospf, ospf_vrf, interface_ospf
• Model files
• Test files
• Documentation and examples

Breaking Changes

None. All new attributes are optional.

Documentation

Comprehensive documentation created in EPIC-510-ospf_advanced_support/:

• YANG-EXPLORATION-NOTES.md - Complete YANG analysis
• CLI-VERIFICATION-RESULTS.md - Device testing results
• YANG-VERSION-COMPATIBILITY.md - Version compatibility analysis
• PROVIDER-TEST-RESULTS.md - Testing evidence
• PROVIDER-PHASE-COMPLETE.md - Phase summary

Additional Notes

• Implementation follows established patterns from previous Epics
• All YANG paths verified in YANG Suite
• CLI behavior validated on live devices
• Version compatibility ensures pipeline success
• Ready for schema and module implementation

---

This PR implements advanced OSPF configuration features for the IOS-XE provider, adding support for log-adjacency-changes, NSF (Non-Stop Forwarding), max-metric router-lsa, fast-reroute, redistribute options, and multi-area interface configurations.