**Session Date/Time:** 17 Mar 2026 08:00 # [MBONED](../wg/mboned.html) **IETF 125 - Brisbane, Australia** **Chairs:** Lenny Giuliano, Greg Shepherd **In-room Delegate:** Jeffrey Zhang --- ## Summary The MBONED working group met to discuss the status of active documents, new use cases for multicast in Large Language Model (LLM) synchronization, a proposal for dynamic internet multicast tunneling, and a report on real-world multicast deployment for professional sports streaming. Several documents are currently in Working Group Last Call (WGLC), and the chairs emphasized the need for community feedback to advance them. --- ## Key Discussion Points ### Working Group Status and Draft Updates * **draft-ietf-mboned-multicast-yang-model**: Currently in WGLC (ends Friday). The draft was updated following extensive off-list feedback. Chairs noted a lack of on-list responses from non-authors and stressed that consensus cannot be determined without broader participation. * **draft-ietf-mboned-redundant-ingress-failover**: In WGLC for a few more weeks. Updated recently after directorate reviews. * **draft-ietf-mboned-non-source-routed-sr-mcast**: Just entered WGLC. This is an informational document regarding deployment options in Segment Routing networks. * **draft-ietf-mboned-multicast-security**: No recent updates; authors were not present. * **draft-ietf-mboned-dorms**: Awaiting Security Directorate review. The request was recently reopened after previous attempts were unsuccessful. * **Parking of Documents**: The authors of **draft-ietf-mboned-cbacc** and **draft-ietf-mboned-ambi** suggested parking these documents due to a lack of current implementation interest or the drafts being overtaken by other technologies (e.g., Multicast extensions for QUIC). ### Multicast for LLM Synchronization **Presentation:** [update-llmsyn-multicast](https://datatracker.ietf.org/meeting/125/materials/slides-125-mboned-update-llmsyn-multicast-00) **Presenter:** Sandy Zhang * **Use Case**: Delivering large-scale models (70GB to 1TB) from central repositories to distributed GPU clouds for real-time inference. * **Challenges**: High concurrency leads to I/O bottlenecks at storage points; "cold start" latency affects inference service availability. * **Technical Analysis**: * PIM-SM and SR-P2MP are suitable for fixed destination sets. * BIER provides a stateless, dynamic alternative for evolving sets of destination GPU clouds. * **Discussion**: The presenter is seeking the appropriate working group for this work (options include MBONED, BIER, PIM, or RTGWG). ### Dynamic Internet Multicast Tunneling **Presentation:** [Dynamic Internet Multicast Tunneling](https://datatracker.ietf.org/meeting/125/materials/slides-125-mboned-dynamic-internet-multicast-tunneling-00) **Presenter:** Lenny Giuliano * **Problem**: While Automatic Multicast Tunneling (AMT) is effective for the last mile, it lacks a standard mechanism for routers to dynamically discover which relay to use for specific sources in the "middle mile." * **Proposal**: Use a BGP Extended Community to encode the AMT relay IP address within the route advertisement for the multicast source. * **Technical Benefits**: Allows core routers to act as AMT gateways/relays dynamically, connecting "multicast islands" across a unicast-only internet without manual GRE tunnel configuration. * **Feedback**: Early feedback from IDR experts suggests that a new BGP attribute might be more appropriate than an extended community for internet-wide propagation. The authors will update the draft to reflect this. * **WG Placement**: The chairs believe MBONED is the correct home as it pertains to relay discovery, similar to RFC 8777 (Dryad). ### Aircast's Internet Multicast Experience: Australian Open **Presentation:** [Aircast's Internet Multicast Experience for the Australian Open](https://datatracker.ietf.org/meeting/125/materials/slides-125-mboned-aircasts-internet-multicast-experience-for-the-australian-open-00) **Presenter:** Sanjay Mishra * **Deployment**: Aircast Live utilized AMT to stream live 1080p/30fps video from the Australian Open to global participants. * **Performance**: Achieved glass-to-glass latency of 500ms–900ms (Melbourne to Boston/India), significantly faster than traditional chunk-based streaming (which ranged from 18 seconds to 2 minutes). * **Implementation Hurdles**: * Lack of external IP addresses at the venue required a complex stack: Wireguard -> GRE -> AMT. * VLC 4.0 had issues with Variable Bitrate (VBR) over RTP, requiring a fallback to Constant Bitrate (CBR). * **Next Steps**: Focus on security/authentication between gateways and relays, multicast encryption for content protection, and adaptive bitrate support. --- ## Decisions and Action Items * **Decision**: **draft-ietf-mboned-cbacc** and **draft-ietf-mboned-ambi** are officially parked due to lack of interest. * **Action Item**: Working Group members are urged to review and comment on **draft-ietf-mboned-multicast-yang-model**, **draft-ietf-mboned-redundant-ingress-failover**, and **draft-ietf-mboned-non-source-routed-sr-mcast** before their respective WGLC deadlines. --- ## Next Steps * Lenny Giuliano and Jeffrey Zhang to update the Dynamic Internet Multicast Tunneling draft based on IDR feedback regarding BGP attributes vs. extended communities. * Sanjay Mishra and Craig (Aircast) to continue investigating multicast encryption and authentication mechanisms for future deployments. * The chairs will monitor the security directorate review for **draft-ietf-mboned-dorms**.