Session Date/Time: 24 Jul 2025 15:00

tiptop Working Group Meeting

Summary

The tiptop working group held its meeting at IETF 121, focusing on IP protocols for deep space networking. The session covered use cases and requirements, IP architecture considerations, DNS configuration, email protocols, header compression, and security considerations for space networking. The group celebrated the adoption of their first working group document on use cases and discussed several individual drafts progressing toward working group adoption.

Key Discussion Points

Use Cases and Requirements Document

Marshall Eubanks presented updates to the use cases document, now adopted as the working group's first official document
Key improvements since version 1 include:
- Enhanced introduction and limitations sections
- Added references to CCSDS standards and LunaNet
- Expanded sections on spacecraft onboard networks (4.5 and 4.7)
- Complete rewrite of security considerations section
Predictable interruptions due to solar conjunctions require planning for communication blackouts lasting approximately two weeks every synodic period
Lunar timing considerations include 56-microsecond daily drift requiring specialized time coordination

IP Architecture for Deep Space

Wes Hardaker presented architecture considerations for IP in deep space environments
Focus on QUIC transport over UDP with support for both IPv4 and IPv6
Transport protocol challenges identified in three categories:
1. Connection establishment and feature negotiation
2. Continuous probing behaviors (congestion control, retransmission)
3. Optional features (multi-streaming, multi-path, FEC)
Solutions emphasize pre-planning and scheduling rather than dynamic adaptation
IPv4 vs IPv6 debate: Working group noted they cannot dictate space agency choices; efficiency considerations favor smaller headers in constrained environments

DNS Configuration in Deep Space

Mark Nottingham outlined approaches for autonomous DNS resolution on celestial bodies
Three main approaches discussed:
1. Pre-walking all needed names with DNSSEC validation
2. Pre-fetching entire zone hierarchies
3. Creating special zones with only required resource records
Key requirement: Avoid DNS resolution across Earth-space links due to long delays
Name hierarchy considerations: Recommendation to use existing delegation structure rather than creating new TLDs

Email Protocol Adaptation

Mark Nottingham presented email protocol modifications for deep space
SMTP limitations: Multiple round-trip requirements make standard SMTP unsuitable for long-delay links
Proposed solution: Convert SMTP to BSMTP (batch SMTP) MIME objects for transmission over HTTP/QUIC
Local processing: Full SMTP functionality maintained within celestial body networks

Header Compression with SCHC

Alexander Pelov demonstrated Static Context Header Compression applicability
Key benefits: Stateless compression, RTT-agnostic operation, very low computational complexity
Compression efficiency: IPv6 headers compressed from 48 bytes to as few as 1-10 bytes
Management considerations: Rules can be time-synchronized and dynamically updated

Security Considerations

Britta Hale and Raphael Robert presented challenges with QUIC/TLS in space environments
Primary issues:
- Long round-trip times affecting handshake completion
- Need for extended session lifetimes conflicting with security best practices
- Post-quantum cryptography requirements increasing bandwidth needs
Proposed solution: Replace TLS handshake with MLS (Messaging Layer Security) for:
- Asynchronous key agreement
- Post-compromise security
- More efficient post-quantum key updates

Decisions and Action Items

Use Cases Document: Continue review and refinement process with focus on security considerations achieving working group consensus
Architecture Document: Address transport protocol considerations and advance toward working group adoption
Requirements Focus: Prioritize defining clear security and operational requirements before selecting specific protocol solutions
Cross-Working Group Coordination:
- DNS considerations to be coordinated with DNSOP working group
- Security solutions to be discussed with relevant security working groups
- SCHC integration to be explored with SCHC working group

Next Steps

Marshall Eubanks to incorporate additional details on predictable interruptions and address security section comments
Wes Hardaker to resolve terminology issues around "store and forward" and add transport protocol clarifications
Security discussion to focus on requirements definition before protocol selection
Working group to consider interim meeting for focused technical discussions on architecture and security requirements
All participants encouraged to contribute to GitHub issues and mailing list discussions for active documents
Montreal IETF 122: Continue progression of architecture document toward working group adoption