Session Date/Time: 12 Nov 2021 16:00

Session: manet

Summary

The MANET session at IETF 112 covered updates on current working group documents, addressed a critical errata for RFC 8175, discussed the status of physical layer-related DLAT extensions, and explored future work items. A significant portion of the session was dedicated to a presentation on the Delay Tolerant Network (DTN) Network Management Architecture, highlighting its potential relevance for MANETs operating in challenged, disconnected, or fragmented environments.

Key Discussion Points

Credit-Based Flow Control Documents:
- Three core documents on diffserver-aware credit-based flow control have moved out of the working group and are currently under review by the Transport Area review team (David Black). Feedback is expected by early December.
- Ronald Tschalär volunteered to be the document shepherd for these drafts.
- A related extension draft, utilizing the 802.1Q header for flow distinction, remains in the working group. It is dependent on the other credit-based flow control documents.
RFC 8175 (DLAT) Errata Resolution:
- An errata (6472) was filed regarding the handling of IP and UDP port addresses in replies to discovery signals in RFC 8175. Specifically, the instruction to swap source/destination IP addresses for a multicast destination was problematic, and UDP port handling was unclear.
- Existing implementations often handle this correctly, but clearer specification is needed.
Physical Layer Related DLAT Extensions (Henning's drafts):
- General Utilization Draft: Discussion is needed on the mailing list regarding the rationale for providing raw parameters (busy time, RX time, TX time) to the router versus a single utilization value.
- Radio Band DLAT Extension: This expired draft is concise and will be proposed for working group adoption due to perceived benefits of explicit frequency and bandwidth information.
- Radio Quality Draft: The approach for presenting radio quality information to the router needs further discussion, likely on the mailing list.
Future Work Items:
- OLSRv2 Router Restarting Issue: An interoperability event identified a problem where OLSRv2 routers restarting could make "unlucky" sequence number choices, leading to neighbors rejecting topology control information. A fix via smarter configuration (without protocol changes) and an informational RFC is being considered.
- DLAT Clarifications and Lessons Learned: A proposed standards-track document from IETF 110 (Lou & Rick) requires volunteers due to the original authors' limited availability.
- Multicast and Federation of Heterogeneous MANETs: The working group previously considered that proprietary multicast solutions might leave no work for MANET. However, the concept of federating heterogeneous MANETs (e.g., in disaster relief with diverse equipment and protocols) could benefit from a routing overlay protocol (supporting unicast and multicast), reigniting interest in MANET-specific multicast solutions.
Routing Overlay and RAW Working Group Overlap:
- The concept of routing overlays for heterogeneous radio networks aligns with ongoing work in the Deterministic Networking (RAW) Working Group, which is focused on providing deterministic service across multiple radio networks.
- RAW has an architecture document addressing similar challenges, and MANET participants were encouraged to engage with RAW discussions.
DTN Network Management Architecture (Presentation by Ed Bergin):
- Problem Statement: Traditional, synchronous, pull-based network management (e.g., SNMP, Netconf) is unsuitable for Delay Tolerant Networks (DTNs) due to significant delays, disruptions, and resource constraints.
- Proposed Solution (DTN-MA): An "open-loop" and "asynchronous" management approach emphasizing local autonomy.
  - Architecture Document: Defines aspirational needs for challenged environments.
  - Application Data Model (ADM): Specifies managed objects and enables expression of autonomous behavior.
  - Asynchronous Management Protocol (AMP): Utilizes very compact encodings (e.g., 26 bytes for an "add contact" command) for efficiency in constrained bandwidth/environments.
- Key Services & Properties: Management beyond performance monitoring; local agents changing configurations autonomously; time/state-based report generation (even without a connected manager); local autonomous parameterized control using cached data; fine-grained access control. Emphasizes intelligent push, minimal message size, absolute/custom data identification, and autonomous operation.
- Relevance to MANET: This approach is highly relevant for MANETs that might fragment due to physical limitations (distance, obstacles, jamming). It allows network fragments to manage themselves autonomously with preloaded guidance and report back when connectivity is restored. It could also offer benefits to non-delay networks by reducing traffic and session overhead, enabling quicker synchronization of autonomous actions taken during disconnections.

Decisions and Action Items

Decision: Rick Taylor will work on updated wording for errata 6472 to clarify IP address swapping and UDP port handling for discovery signal replies in RFC 8175 (main D-LAB specification), with the aim of providing unambiguous implementation guidance.
Action Item: Ronald Tschalär will become the document shepherd for the three credit-based flow control drafts currently under Transport Area review.
Action Item: Ronald Tschalär will initiate a 2-3 week Working Group Last Call for the 802.1Q credit-based flow control extension draft.
Action Item: Ronald Tschalär will initiate mailing list discussions for Henning Rohde's General Utilization and Radio Quality DLAT Extension drafts.
Action Item: Ronald Tschalär will ask Henning Rohde to revive the Radio Band DLAT Extension draft and propose it for Working Group Adoption.
Action Item: Ronald Tschalär will bring the OLSRv2 router restarting problem and the idea of an informational RFC (with Chris Dearlove's input) to the mailing list for discussion.
Action Item: Ronald Tschalär will issue a call for volunteers on the mailing list to work on the "D-LAB Clarifications and Lessons Learned" document.

Next Steps

MANET working group members interested in routing overlays for heterogeneous networks are encouraged to follow discussions in the Deterministic Networking (RAW) Working Group.
Further discussion on the applicability and integration of DTN Network Management Architecture concepts into MANETs, particularly for managing fragmented or intermittently connected scenarios.
Ronald Tschalär to follow up on the discussion regarding routing in Low Earth Orbit (LEO) satellites presented at IETF 112 (potentially in the Routing WG or IRTF).