Session Date/Time: 21 Mar 2024 23:30

pim

Summary

This PIM working group meeting covered the status of various drafts, including IGMP/MLD revisions, point-to-multipoint policy, EVPN multicast YANG, and LISP joint prune extensions. Discussions focused on potential adoption of new drafts and progression of existing ones towards last call, as well as key technical challenges in multicast deployment, particularly around backwards compatibility and scaling solutions.

Key Discussion Points

IGMP/MLD Version Compatibility: A major discussion point revolved around IGMPv3 and MLDv2 and how to handle fallback to older versions (v2) when older queriers are present on the link. Concerns were raised about denial of service implications and the need for hosts to be able to ignore older queries.
Point-to-Multipoint Policy: The working group discussed the status of the SR point-to-multipoint policy drafts, including the PIM and SRv6 components. Implementation status and potential for last call were assessed. The OEM aspects of MPLS vs. SRv6 were also highlighted.
EVPN Multicast YANG: An update was provided on the EVPN multicast YANG model draft.
LISP Joint Prune Extensions: Discussion about moving ahead with this document after previous feedback from the last call.
PIM Flooding Mechanism: A draft proposing improvements to the PIM flooding mechanism using router IDs was presented, generating interest for adoption.
PFM Sub-TLVs: A new draft presented the concept of using sub-TLVs within PFM TLVs to announce additional information about multicast sources. There was a suggestion about possibly combining this with the PIM flooding improvements work.
Hierarchical Bit String Beer: Discussion on scaling stateless multicast with a mix of SIP-based and bit string-based approaches for large networks. The recursive bit string structure was discussed and a reference implementation shown.
IGMP Multiple Upstream Interface Proxy: Discussion on enabling IGMP proxy devices to use multiple upstream interfaces. Feedback indicated a preference for this to be addressed as informational document and local behavior, not standardized.
SR Multicast Options: A presentation on multicast options in a source segment routing network, specific for non-source routed options, triggered a discussion about the applicability of different solutions (e.g. beer, SR P2MP).

Decisions and Action Items

MoFR: Start a working group last call on the list, if there are no complaints.
PIM Light: Start the formal working group last call for this draft, Sandy to chair the working group last call for this draft.
Point to Multipoint Policy (PIM): Take it to the list to start a last call.
Point to Multipoint Policy (SRv6): Take it to the list to start a last call.
IGMPv3/MLDv2: Add some succinct text to the document to clarify behavior related to IGMPv2 and older MLD queriers, focusing on recommendations. Text proposal by Brian, Steve and others.
PIM Flooding Mechanism: The working group will follow-up on the list for adoption.
PFM Sub-TLVs: Discuss with Jeffrey and Sandy and others to agree on document structure. The working group will follow-up on the list for adoption.
IGMP Multiple Upstream Interface Proxy: The working group will follow-up on the list for adoption.

Next Steps

The working group will use the mailing list to further discuss the issues raised during the meeting, particularly related to the IGMPv3/MLDv2 compatibility and the document structure for PFM.
Several drafts will progress to working group last call after further discussion on the list.