Session Date/Time: 27 Mar 2023 06:30

tvr

Summary

The inaugural meeting of the Time-Variant Routing (tvr) working group focused on defining scope, goals, and identifying potential areas of collaboration. Presentations covered use cases, existing time-variant information models (Aeronautical Information Exchange Model - AIXM), network traffic examples, contact graph routing (CGR), forwarding policies, and the use of ALTO for exposing time-variant routing information. The session concluded with a call for participation in drafting Internet drafts to address the working group milestones.

Key Discussion Points

Use Cases: Discussion of use cases including local resource preservation, adapting to external conditions (e.g., power, comm), and predicted mobility. There was consensus on creating a use case document as an informational product of the working group.
AIXM Temporal Model: Introduction of the AIXM temporal model as a potential source of inspiration for time-variant information modeling. Focus was on its ability to convey state as a function of time, absolute vs. periodic time, and the separation of information producers and consumers. Limitations regarding parameter interrelation and planning horizon were noted.
Network Traffic Use Cases: Discussion of network traffic patterns that vary over time, such as traffic surges due to events, link upgrades, and device failures. These use cases motivate the need for time-variant routing to optimize resource utilization.
Contact Graph Routing (CGR): Overview of CGR's history and its application in delay-tolerant networking, particularly in space communications. CGR utilizes contact plans, which are schedules of communication opportunities between nodes.
Forwarding Policies: Exploration of forwarding policies related to bundle protocol and IP, including policies for handling full memory stores, new route installations, and packet expiration. The suitability of applying IP-specific policies was questioned, and the potential for the DTN working group to take on this work was discussed.
Contact Plan Data Model: Proposal for standardizing a data model and file format for contact plans, enabling comparison, revisions, and archiving. JSON was presented as an example encoding.
ALTO for Time-Variant Routing: Discussion of using ALTO (Application-Layer Traffic Optimization) to expose time-variant routing information to applications. ALTO's calendar cost feature could be leveraged to provide both current and future views of routing costs.
Probability of Schedules: The topic of accounting for uncertainty and probability of calendars and schedules being correct was brought up.

Decisions and Action Items

Decision: The working group will create a use case document as an informational product.
- Action Item: Volunteers are requested to help author the use case document; coordinate on the mailing list.
Action Item: Participants to review the AIXM temporal model and discuss its applicability to tvr on the mailing list.
Action Item: Explore how to express parameters as a function of time, either time position, or another input parameter.
Action Item: Participants to discuss the scope of forwarding policies (IP vs. bundle protocol) on the mailing list.
Action Item: Refine the data model for contact plans, taking into account comments on the list of destinations, mandatory start/end times, and bandwidth/latency considerations.
Action Item: Explore how to handle more dynamic parameter definitions and better understand link attributes for time variant routing schedules.

Next Steps

Actively participate in discussions on the mailing list to refine requirements and identify areas of collaboration.
Form groups to work on consolidated Internet drafts addressing the working group milestones (problem statement, use cases, requirements, information model, data model, applicability statements, considerations).