IGP Flexible Algorithms Reverse Affinity Constraint
RFC 9917, “IGP Flexible Algorithms Reverse Affinity Constraint”, is a Proposed Standard document published in January 2026 by P. Psenak, J. Horn, A. Dhamija. It updates RFC 9350, RFC 9843. The canonical text is published by the RFC Editor.
Abstract
An IGP Flexible Algorithm (Flex-Algorithm) enables the computation of constraint-based paths within an IGP domain, allowing operators to influence path selection according to administrative policies. This document defines an extension to Flex-Algorithm that allows the inclusion or exclusion of links from path computation based on Administrative Groups (also known as link affinities) associated with the reverse direction of the path under computation.
This document updates RFCs 9350 and 9843 by introducing the new IANA registry that specifies the ordered set of rules that are used to prune links from the topology during the Flex-Algorithm path computation.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
The canonical text of RFC 9917 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.
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- RFC 9912 Reliable and Available Wireless Architecture
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