RFC 9917 - IGP Flexible Algorithms Reverse Affinity Constraint

• Status: Proposed Standard
• Published: January 2026
• Stream: IETF
• Errata: RFC Editor Errata

Abstract

This document defines reverse-direction Administrative Group constraints for IGP Flex-Algorithm path computation and updates RFCs 9350 and 9843 with a new IANA registry for ordered path computation rules.

Contents

• 1. Introduction
• 2. Requirements Language
• 3. Use Case Example
• 4. Deployment Consideration
• 5. IS-IS Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
• 6. IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
• 7. IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
• 8. OSPF Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
• 9. OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
• 10. OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
• 11. Calculation of Flexible Algorithm Paths
• 12. IANA Considerations
• 13. Security Considerations
• 14. References
• Authors' Addresses

Related Resources

• Official Text: RFC 9917
• Official Page: RFC 9917 DataTracker
• Errata: RFC Editor Errata