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Session Date/Time: 17 Mar 2026 06:00

IDR - Inter-Domain Routing Working Group

IETF 125 - Session B Chairs: Susan Hares, Jeff Haas, Keyur Patel AD: Ketan Talaulikar

Summary

The IDR Working Group met to discuss the status of active drafts, review several new proposals related to AI/ML data center networking, and discuss the proposed update to the WG charter. Key themes included traffic engineering in high-performance fabrics, BGP extensions for Segment Routing (SRv6) and Flexible Algorithms, and security policy signaling. Significant discussion occurred regarding the necessity of new BGP communities where existing mechanisms (like link-bandwidth) might suffice, and the jurisdictional boundaries between IDR and other working groups like SPRING and SIDROPS.

Key Discussion Points

WG Status and Charter

• Susan Hares reported that draft-ietf-idr-vpn-ora has been sent to the IESG. Six additional drafts are in the post-Working Group Last Call (WGLC) shepherd phase, including draft-ietf-idr-sr-policy-ifit, draft-ietf-idr-sr-policy-nrp, draft-ietf-idr-nhc, and draft-ietf-idr-rt-derived-community.
• Charter Update: The proposed charter aims for more detail to avoid late-stage IESG concerns. A primary focus is maintaining BGP scaling and interoperability as more information is shoved into the protocol. Jeff Haas (via chat) and Susan Hares discussed the challenge of BGP being a "shared technology" and the risks of "breaking" the protocol with non-routing data.

1-2. BGP Deterministic Path Forwarding (DPF)

• Presenter: Kevin Wang
• Discussion: The proposal introduces "colored" EBGP sessions and routes to partition physical fabrics into logical ones, targeting AI/ML workloads (RDMA/ROCEv2).
• Technical Points: Supports strict mode (OPEN capability negotiation) and loose mode (route matching). Provides mechanisms for primary/backup path selection and load balancing across fabrics.
• Q&A: Nan Geng asked about existing routing policy precedence; Kevin confirmed local policy takes precedence. Sandy Zhang suggested using communities alone rather than session-based restrictions. Jeff Tantsura questioned whether backup paths are BGP constructs or data-plane implementations, urging the authors to be specific about how these routes are installed in the FIB.

1-1. BGP YANG

• Presenter: Jeff Haas
• Draft: draft-ietf-idr-bgp-model
• Discussion: Jeff provided an update on version 18, which includes cleanup for the Broadband Forum and NMOP. Significant fixes were made to community regular expressions and the filtering language. A point of contention remains regarding the use of submodules vs. top-level modules. Jeff Haas announced he will step down from BGP YANG roles once this draft is published.

1-3. BGP PORT EC for AIDC

• Presenter: Zhuang Rui
• Discussion: Proposes a new BGP Extended Community to carry Port IDs to avoid last-hop congestion in AI data centers. This allows senders to negotiate bandwidth with the destination leaf before transmitting.
• Q&A: Krity questioned the necessity of BGP for this function. Jeff Tantsura raised concerns about scaling and the impact of route aggregation on port-specific communities.

1-4. Data Center Efficiency Proposals

• Presenter: Xiao Hu
• 1-4-1. Fully Adaptive Routing Ethernet using BGP: Focuses on path bandwidth for multihoming. Stephane Litkowski and Jeff Tantsura strongly questioned the need for a new community, arguing the existing Link Bandwidth/DMZ community is already deployed and sufficient.
• 1-4-2. BGP Neighbor Discovery: Targets OCS-based data centers. Stephane Litkowski questioned if this belongs in IDR, as it describes a non-BGP protocol for neighbor discovery. Susan Hares noted that auto-configuration work had previously moved to other groups (e.g., LSVR).

1-5. BGP Extensions for Inter-Domain Flexible Algorithm with SRv6

• Presenter: Li Yan
• Discussion: Proposes a "Flex-Algo Extended Community" to maintain algorithm consistency across AS boundaries.
• Q&A: Krishnaswamy and Stephane Litkowski pointed out that Color Prefix Routing (CPR - RFC 9273) already addresses this in a more generic way, especially for multi-administration scenarios where Algo IDs might clash.

1-6. BGP Signaling for Multipath Traffic Engineering Junction States

• Presenter: Jeffrey Zhang
• Discussion: Introduces a new MPTE SAFI to signal Directed Acyclic Graph (DAG) tunnels. Reuses and extends the Tunnel Encapsulation Attribute (RFC 9012) to describe P-hops and N-hops. A new "Any Encapsulation Tunnel" type was proposed for native forwarding.

1-7. SRv6 Policy SID List Optimization Advertisement

• Presenter: Zafar Ali
• Discussion: This work follows the adoption of the base requirement in the SPRING WG (draft-ietf-spring-srv6-policy-resource-optimization). It adds a flag to BGP-LS to indicate when a node SID has been optimized (skipped) by the ingress. Susan Hares noted the request for adoption but emphasized that WGLCs for existing drafts take priority.

1-8. BGP Communities for Security Policy Intent

• Presenter: Yangfei Guo
• Discussion: Proposes a BGP Large Community ("ROA strict") to signal that a downstream AS should drop routes if RPKI ROV result is "not found" or "invalid."
• Q&A/Decision: Susan Hares and Stephane Litkowski clarified that security mechanisms involving RPKI expectations fall under the jurisdiction of the SIDROPS Working Group. The authors were directed to present there.

Decisions and Action Items

1. Jurisdiction: draft-guo-idr-security-policy-intent (Security Policy Intent) must be handled in SIDROPS.
2. SR-Related Drafts: Authors of drafts using SR functions are requested to include a section explaining the mapping to SPRING functions and interactions with other controllers like PCE.
3. BGP YANG: The authors of draft-ietf-idr-bgp-model will resolve the submodule issue with NMOP authors to finalize the draft for publication.

Next Steps

1. Charter Finalization: The chairs will set a deadline (approximately three weeks) for final comments on the new WG charter.
2. Flowspec v2: An editing session is scheduled for Wednesday to finalize the base draft (draft-ietf-idr-fsv2-ip-basic) by April/May.
3. Adoption Queue: Participants are encouraged to comment on active WGLCs to clear the queue for new adoption calls.
4. Technical Follow-up: Authors of the Path Bandwidth proposal (draft-hu-idr-bgp-adaptive-routing) need to provide stronger justification for not using the existing link-bandwidth community.

Session Date/Time: 20 Mar 2026 01:00

IDR

Summary

The IDR Working Group (WG) met at IETF 125 to discuss the status of active drafts, early allocation procedures, and several new proposals. Key themes included extensions for Segment Routing (SR) Policies, BGP Link-State (BGP-LS) enhancements for BGP-only data center fabrics, and advancements in BGP Flow Specification Version 2 (FSv2). Significant discussion occurred regarding the decoupling of Network Resource Partition (NRP) IDs from SR Policies, the necessity of centralized Queue Pair (QP) steering for AI workloads, and addressing BGP convergence delays during route withdrawals.

Key Discussion Points

WG Status and Early Allocations

• Susan Hares provided a status update on several drafts, noting that draft-ietf-idr-vpn-prefix-orf and draft-ietf-idr-sr-policy-nrp are progressing.
• A "mea culpa" was issued regarding early allocation confusion for SR Policy. Moving forward, authors must include cross-working group sections (especially for SPRING and PCE) to avoid late-stage architectural mismatches.
• Susan Hares emphasized that no early allocation should be used in released products unless assigned by IANA.

SR Policy and BGP-LS Extensions

• 1-0. IDR WG Chairs' slides
• 1-1. BGP YANG: Progress on draft-ietf-idr-bgp-model.
• SR Policy Metric: Ka Zhang discussed reusing BGP-LS SR Policy metric type registries for the BGP SR Policy SAFI. Zhengqiang Li noted an agreement to merge this work with related efforts from China Mobile.
• 1-4-2. BGP Neighbor Discovery: Changwang Lin proposed a new BGP Capability to exchange Interface Indexes to identify unnumbered parallel BGP peers. Tony Li and Kiriti Kompella discussed the industry trend of using BGP as an IGP in data centers due to historical issues with OSPF/IS-IS implementations in those environments.
• 1-7. SRv6 Policy SID List Optimization Advertisement: Yisong Liu presented a method to optimize SRH space by excluding the endpoint's node SID for data traffic while retaining it for OAM.

Network Resource Partition (NRP) and BFD

• 1-5. BGP Extensions for Inter-Domain Flexible Algorithm with Segment Routing over IPv6 (SRv6) (Discussion of draft-ietf-idr-sr-policy-nrp): Zhengqiang Li proposed decoupling NRP IDs from SR Policies via a new Extended Community to improve scalability. Zafar Ali challenged the need for a separate NRP ID, suggesting that "Color" already carries the necessary intent.
• BFD Configuration in SR Policy: Zhengqiang Li proposed carrying BFD/S-BFD parameters in BGP SR Policy. Jeff Haas (as BFD Chair) advised against carrying timers in the control plane, as implementations typically do not respect them when signaled this way; he recommended passing only minimal state like discriminators.

BGP-LS for BGP-Only Fabrics

• 1-4-1. Fully Adaptive Routing Ethernet using BGP (Discussion of draft-ietf-idr-bgp-ls-bgp-only-fabric): Arvind Babu detailed how BGP-only networks (common in AI-DC) can export topology using node, link, and prefix NLRIs. Keyur Patel suggested cross-working group coordination with LSVR.

Flow Specification Version 2 (FSv2) and AI Workloads

• FSv2-IETF125-side meeting (Discussion of draft-ietf-idr-fsv2-ip-basic): Jiming proposed a destination QP (Queue Pair) component for FlowSpec to steer RDMA/RoCE v2 traffic for AI training. Jeff Tantsura and Jeff Haas expressed skepticism, noting that modern chipsets already hash on QPs and that central orchestration via BGP FlowSpec might be unnecessarily complex and slow.
• 1-8. BGP Communities for Security Policy Intent (Discussion of draft-ietf-idr-flowspec-redirect-ip): Yong Huang proposed using Destination IP Communities/AS Paths as FlowSpec match criteria to aggregate rules and save hardware ACL entries.

BGP Forwarding and Convergence

• 1-6. BGP Signaling for Multipath Traffic Engineering Junction States (Discussion of draft-ietf-idr-bgp-fwd-rr): Manakamana Mishra discussed using the Next Hop Dependent Characteristics (NHC) attribute (draft-ietf-idr-nhc) to prevent infinite label allocation loops in BGP L3VPNs with Next Hop Self.
• Convergence Problem Statement: Yuhang Li presented research on "delayed elimination of invalid alternatives" during route withdrawals. AC Lindem pointed to RFC 9815 (BGP SPF) which addresses similar link-failure exploration issues.

Decisions and Action Items

• draft-ietf-idr-sr-policy-metric: Authors (Ka Zhang) to meet with IANA (Amanda Baber) to finalize registry requirements.
• draft-ietf-idr-sr-policy-metric: Authors agreed to merge this draft with related China Mobile work (Zhengqiang Li) in the next version.
• draft-ietf-idr-bgp-bfd-strict-mode: Noted as needing shepherd updates from John Scudder.
• NRP ID Discussion: Susan Hares to discuss the feedback from Zafar Ali regarding NRP vs. Color intent with the SPRING WG.

Next Steps

• draft-ietf-idr-sr-policy-metric: A second early allocation call will be issued after authors update the draft with IANA-recommended changes.
• draft-ietf-idr-bgp-ls-bgp-only-fabric: Moving toward expert review for code points; implementations are underway.
• draft-ietf-idr-fsv2-ip-basic: Authors to address performance and complexity concerns raised regarding central QP steering.
• BGP Convergence: Researcher Yuhang Li encouraged to refine the problem statement to focus on inter-AS scenarios based on feedback.

Related Documents

draft-ali-idr-srv6-policy-sl-opt-distribution-00, draft-guo-idr-security-policy-intent, draft-hu-idr-bgp-adaptive-routing, draft-ietf-idr-bgp-bfd-strict-mode, draft-ietf-idr-bgp-fwd-rr, draft-ietf-idr-bgp-ls-bgp-only-fabric, draft-ietf-idr-bgp-model, draft-ietf-idr-flowspec-redirect-ip, draft-ietf-idr-fsv2-ip-basic, draft-ietf-idr-nhc, draft-ietf-idr-rt-derived-community, draft-ietf-idr-sr-policy-ifit, draft-ietf-idr-sr-policy-metric, draft-ietf-idr-sr-policy-nrp, draft-ietf-idr-vpn-ora, draft-ietf-idr-vpn-prefix-orf, draft-ietf-spring-srv6-policy-resource-optimization