**Session Date/Time:** 17 Mar 2025 10:00

# bier

## Summary
This IETF 112 bier session covered several topics including working group document status, overlay discussions, inter-op test results, and FRR considerations. Key discussions revolved around PIM light, the next protocol field in the beer header (specifically related to upstream vs. downstream assigned labels), and the Fast Reroute (FRR) draft.

## Key Discussion Points

*   **Working Group Document Status:** Several drafts are in the RFC Editor queue or IESG status. The group wants to move key documents like non-MPLS encoding and OSPFv3 extensions to IESG at the earliest. Focus was put on the need for a shepherd write-up for OAM requirements.
*   **PIM Light and Joint Prune Attribute:** There was a discussion regarding the necessity of the join prune attribute in the PIM light overlay draft. Some argued that the information can be derived from the beer header. Concerns were raised about implementation complexity on the data path and security considerations.
*   **Inter-op Testing Results:** Results from inter-op testing involving Nokia, Juniper, Huawei, and Ixia were presented. The main interrupt issue was the "next protocol" field in the beer header due to differing implementations of upstream vs. downstream assigned labels.
*   **Upstream vs. Downstream Labels in Beer:** In the interop test report, Nokia uses upstream-assigned service labels (configured statically in the provider tunnel attribute), while Juniper uses downstream-assigned labels. The discussion focused on clarifying whether the DCB label (domain-wide and block) usage described in RFC 9573 necessitates downstream assignment. The conclusion was that RFC 9573's use of the DCB label indeed necessitates downstream assignment and that the "next protocol" field should be set to 1.
*   **FRR Considerations:** Tolis provided a review of the FRR draft, highlighting the technology's potential benefit for multicast resilience and areas for improvement. Points included emphasizing the technology's unique capabilities, addressing MPLS applicability, clarifying tunnel-based vs. FOR-based approaches, and ensuring consistency with existing FRR terminology. The usefulness of "Partial deployment" was questioned and whether it complicated the draft unnecessarily.

## Decisions and Action Items

*   **OAM Requirements:** Greg will commit to shepherd write-up.
*   **PIM Light:** Bring the discussion about the join prune attribute to the working group mailing list for further discussion.
*   **Beer Next Protocol:** Bring the issue of downstream vs. upstream label assignment to the MPLS working group.
*   **FRR Draft:** Mike will review the review from Tolis, and implement simple fixes.

## Next Steps

*   Continue discussion on the PIM light draft and the beer header labeling scheme on the respective mailing lists.
*   MPLS working group to discuss the label assignment issue.
*   Implementer feedback is requested to confirm the feasibility of the current FRR draft. Vendors who wish to consider implementing this technology should coordinate, to test the feasibility and interoperability.