**Session Date/Time:** 11 Nov 2021 16:00

# panrg

## Summary

The panrg session covered administrative updates, including a brief IAB review of the research group's activities. Key discussions revolved around the status of the `pan-rg-questions` draft, the evolution of the `vocabulary of path properties` draft, and a presentation on describing satellite networks using panrg terminology. A significant portion of the session was dedicated to an analysis of multi-path Quick (MPQUIC) against the impediments to path-aware networking deployment (RFC 9049), which sparked a broader conversation about the future of multi-path in the IETF and the role of panrg.

## Key Discussion Points

*   **Administrative Updates**
    *   The IETF/IRTF Notewell was presented, emphasizing IRTF follows IETF intellectual property rules.
    *   Meeting logistics (audio/video off unless speaking, headphones recommended, VPN issues, pre-loaded slides).
    *   Corey was thanked for serving as minutes taker.
    *   The agenda included presentations on vocabulary, satellite networks, multi-path selection, followed by 40 minutes of open mic time.
*   **pan-rg-questions draft Status**
    *   The `pan-rg-questions` draft is awaiting its document shepherd and final feedback from Gauri and GitHub.
    *   Brian Trammell committed to rolling a new draft version during the open mic session.
*   **IAB Review of panrg**
    *   The IAB conducted a review of panrg in September/October.
    *   **Next Steps identified for panrg:**
        *   Continue answering the research questions in the `pan-rg-questions` draft. The path properties draft is a good answer to the first question.
        *   Consider research applications of Path Aware Networking (PAN) properties to IETF protocols (e.g., Spencer's multi-path work).
        *   Reached out to the ALTO Research Group to invite them to panrg for related work.
        *   panrg should operate as a general venue for discussions at the intersection of routing and transport.
*   **Vocabulary of Path Properties (Rees Kressin)**
    *   **Draft Updates:**
        *   Revised 'entity' definition to be more specific: entities play a role related to pathway networking for particular paths and flows (e.g., data plane for forwarding, control plane for influencing forwarding).
        *   Formalized 'transparency' definition as a function `f(flow F, meta-information M) = action A`, where the node is transparent if `A` is constant regardless of `M`.
    *   **Discussion on Defining Terms:**
        *   The draft aims to define key terms used in other panrg documents (e.g., "routing domain identifier" from the questions draft).
        *   Spencer Dawkins requested adding a pointer to the GitHub repository in the draft.
        *   Discussion on the scope of definitions: how deep to go? Brian Trammell suggested stopping when existing IETF definitions can be referenced, and for core terms, a "research group last call" approach.
        *   Sabine D'Hondt suggested context-specific definitions (e.g., "endpoint" in routing vs. transport). Rees clarified the document aims for general definitions within the panrg scope.
        *   Gauri emphasized defining "endpoint" and "end-to-end".
    *   **Feedback Mechanism:** GitHub issues are preferred for specific definition feedback; mailing list for general scope discussions.
*   **Satellite Networks and Path Properties (Nikola):**
    *   **Background:** Historical TCP tuning for GEO satellites, challenges with Quick over satellite, increasing GEO/LEO capacities, need for satellite-aware transport.
    *   **Application of panrg Terminology:** The authors attempted to describe generic satellite communication (satcom) systems using the `vocabulary of path properties` terms (host, node, path properties).
    *   **Proposed Next Steps:**
        *   Rees Kressin suggested mapping the satcom problem space to the panrg research questions.
        *   Brian Trammell expressed interest in a deeper exploration of satcom in panrg, potentially as an "architecture" document illustrating how the internet adapts to this technology.
        *   Gauri offered to help split the existing TSVWG document (which was very transport-centric) into two: one defining satellite systems and their properties/challenges for panrg, and another for transport fixes for TSVWG. This was positively received.
*   **Multipath Selection Strategies (Spencer Dawkins)**
    *   **Observation:** Multi-path is becoming ubiquitous, common, deployable, and ambitious (SCTP, MPTCP, DCCP, and now MPQUIC).
    *   **MPQUIC Analysis Against RFC 9049 (Impediments to PAN Deployment):** Spencer assessed the proposed multi-path Quick extensions against the 13 lessons learned from RFC 9049.
        *   **Positive Outlook:** MPQUIC performs well against most impediments, especially as extensions are endpoint-to-endpoint and encrypted, negating concerns about network operator involvement or trust of midpoints (which were major showstoppers for older PAN technologies).
        *   **Remaining Challenges/Considerations:**
            *   Justifying deployment depends on the path selection strategy (e.g., bandwidth aggregation).
            *   "High quality" alternative paths are crucial, and "quality" is application-dependent (Gauri).
            *   Support in endpoint stacks depends on advanced scheduling, which is currently out of scope for the initial MPQUIC draft.
            *   Planning for failure requires knowing when to discard unhelpful paths.
    *   **Discussion:**
        *   Med pointed out that benefits for early adopters have changed post-QUIC, with major players driving initial deployments.
        *   Cyril highlighted that partial deployment benefits heavily rely on the existence of *different high-quality* alternative paths.
        *   Maria agreed, pointing to the IAB workshop on measuring user experience report as relevant.
        *   Tanji asked about the different strategies for multi-path (endpoint-based like MPQUIC vs. midpoint-proxy like ATSS/5G UPF). Spencer noted this is a key question for panrg.
        *   Brian Trammell sees MPQUIC as an exciting "actuation side" testing ground for path awareness, even before full sensing mechanisms.
        *   Chris pointed out the complexity of multi-path on phones (Wi-Fi + cellular), where different entities make steering decisions, potentially leading to competition.
*   **Open Mic / General Discussion**
    *   The conversation continued on multi-path, its connection to path awareness, and where various research aspects fit within the IETF (panrg, iccrg, or other groups).
    *   Zohar and Colin acknowledged the overlap across groups and generally favored broad groups over hyper-specialized ones.
    *   Sabine D'Hondt mentioned an ALTO WG draft under IESG review that conveys abstracted path information between endpoints, which could be relevant to panrg's discussions on path properties and application performance.

## Decisions and Action Items

*   **pan-rg-questions Draft:** Brian Trammell rolled a new version (pan-rg-questions-11) during the meeting to incorporate feedback from Gauri and GitHub.
*   **Vocabulary of Path Properties Draft:**
    *   Rees Kressin will add a pointer to the GitHub repository in the draft.
    *   Community to provide specific definition feedback via GitHub issues; general scope discussions on the mailing list.
*   **Satellite Networks Draft:** Nikola and co-authors will revise the draft to focus on defining satellite systems and discussing panrg research questions, potentially splitting transport-specific content into a separate document or WG. Gauri offered direct assistance with this.
*   **Multi-path Discussion Follow-up:**
    *   Spencer Dawkins will send links to relevant ATSS/multipath-quick interim drafts to the panrg mailing list.
    *   Sabine D'Hondt will send a link to the ALTO working group draft on conveying abstracted path information to the panrg mailing list and consider presenting it at a future meeting.
    *   Chairs of panrg, iccrg, and IETF ADs will discuss appropriate venues for various multi-path research questions.

## Next Steps

*   **Community Engagement:** Provide feedback on the `vocabulary of path properties` draft, particularly for core terms (entity, node, host, link, path element, path), via GitHub issues before the next meeting.
*   **Satellite Networks Document:** Nikola and co-authors to develop the panrg-focused version of the satellite networks document, leveraging panrg terminology and addressing research questions.
*   **Multi-path Research:** Continue to explore the implications of multi-path Quick and other multi-path technologies, particularly regarding advanced scheduling, path selection strategies, and their interaction with path awareness concepts.
*   **Guiding Principles:** Continue to follow the IAB review recommendations: answer panrg questions, consider research applications of PAN to IETF protocols, and operate as a venue for routing and transport intersections.