Session Date/Time: 27 Jul 2023 16:30

cats

Summary

The CATS (Computing-aware Traffic Steering) working group meeting focused on terminology, problem statements, use cases, requirements, architecture, and compute metrics. Key discussions revolved around defining service-related terms, refining use cases, and identifying relevant metrics for traffic steering. The group emphasized the importance of aligning the work with existing standards and focusing on problems specific to the IETF's expertise.

Key Discussion Points

Terminology: A presentation proposed generic definitions for "service," "computing service," "service instance," and "service contact instance" to avoid overloaded terms and ensure clarity within the CATS context. There was discussion about the clarity of the "service contact instance" definition and its relationship to load balancing.
Problem Statement and Use Cases: The problem statement and use cases draft was discussed. It covers service selection and traffic steering challenges in edge computing environments. A new use case, compute-aware SD-WAN, was added. There was a discussion about adding AI-related use cases but also the need to focus on core traffic steering problems and avoid overlap with other standards groups like Kubernetes. The discussion evolved into whether CATS should focus on proactive (influencing placement) or reactive (steering traffic for workloads that have already been placed) use cases, with the conclusion being that CATS should focus on reactive (steering traffic).
Requirements: Requirements derived from use cases were presented, covering dynamic service selection, metric representation and distribution, flexible usage of metrics, session continuity, and security. Comments included ensuring requirements are not too prescriptive and refining use cases to derive clearer requirements.
Architecture: An architecture framework was presented, introducing new components (CCIB, CNMIB, Casa Path Calculation) and interfaces to facilitate CATS deployment. There was a reminder to ensure it does not conflict with any existing architectures.
Compute Metrics: Discussions about how to identify the core metrics relating to compute for traffic steering and working with other standardization groups like ALTO. Proposals were made to start with simple metrics like delay (network propagation + processing time) and service capabilities. The concept of a "preference index" for service steering and a "site availability index" for rapid rerouting around outages was raised. The issue of defining "green" metrics and related challenges (energy consumption modeling, tradeoff between energy savings and user experience) were also introduced.

Decisions and Action Items

Record Terminology: Agreed to record agreed-upon terminology in the framework document.
Refine Use Cases: Focus on refining use case descriptions for conciseness and clarity. Authors of existing drafts to try to write up use case in concise way for others to move into main use case draft, and make space for the requirements.
Address Comments on Requirements: The WG is now responsible for the document on requirements and the editors will try to address all comments.
Coordinate Architecture Documents: Authors of the two architecture framework documents should collaborate to identify differences, common ground, and points for further discussion.
Coordinate on Metrics: The WG will work to ensure their work on metrics doesn't conflict with any other standardizing bodies. The chairs plan to reach out to ALTO to discuss overlapping needs.
Clarify Scope: Explicitly define and maintain focus on problems within the IETF's expertise (traffic steering) and avoid addressing issues better suited for other standards bodies (service placement).

Next Steps

Address all existing comments on use cases and requirements document to better address the use cases and requirements.
Refine framework and architecture documents.
Further discussion and refinement of metrics proposals on the mailing list and potentially in joint interim meetings with related working groups.