Session Date/Time: 15 Jan 2025 13:00

CATS

Summary

This interim meeting focused on progressing the CATS Use Cases and Requirements draft, and defining next steps for the recently adopted CATS Metrics draft. Discussions aimed at consolidating individual use case drafts into the working group (WG) document, clarifying their scope, and identifying specific requirements for the CATS framework. A key decision was made regarding the broad scope of the Metrics draft. Authors of individual drafts were assigned specific action items to contribute text and requirements to the WG documents before the next IETF meeting in Bangkok.

Key Discussion Points

Chairs' Objectives:
- Consolidate the Use Cases and Requirements draft, aiming for completion and a decision on publication (RFC vs. consensus-complete informational document). The WG document should capture key use cases and requirements, not every conceivable one.
- Define next steps for the Metrics draft, including dynamic aspects.
- Authors of individual drafts were encouraged to propose specific edits to the WG document, rather than waiting for editors.
Green Challenges Use Case:
- Presented challenges related to green computing-aware traffic steering, including energy consumption modeling, joint optimization of compute/network, service assurance, and green energy utilization.
- Discussion ensued on whether this was an "applicability statement" or a "use case" that imposes new requirements.
- A sense of those present indicated that the concept of "cost" (potentially linked to energy and carbon footprint) is a crucial metric for CATS, even if the raw "level 0" energy metric details are deferred to the Green WG. This implies a requirement on the CATS metrics framework to accommodate cost.
- Concern was raised about getting ahead of the Green WG's work on network energy consumption.
ITS Use Cases:
- Presented motivation for including Intelligent Transport Systems (ITS) scenarios (e.g., connected cars, drone navigation) to compensate existing CATS use cases.
- Specific requirements highlighted included real-time context migration, proactive load balancing, dynamic clustering, and differentiated packet scheduling, which were seen as not fully covered by the current WG document.
- The proposed use cases (Context-aware navigation, Edge-assisted cluster-based MAC, self-adaptive interactive navigation, cloud-based drone navigation) were discussed in the context of integrating them into the existing ITS section of the WG document.
Industrial Use Cases:
- Presented unique characteristics and requirements of industrial internet scenarios, emphasizing collaborative control, time-sensitive tasks, and deterministic needs.
- Typical use cases included computing-aware industrial robots, cloud terminals, and multi-application collaboration.
- The industrial sector was identified as a significant area not fully covered by the current WG use cases. The need for a dedicated subsection or expanded coverage was discussed.
- A reminder was given to consider potential overlap and distinction from DetNet work.
O-RAN Use Cases:
- Presented the application of CATS for O-RAN mid-haul networks, focusing on providing flexibility for DU-CU connectivity (F1 interface, applicable to 3GPP as well).
- The draft detailed architectural descriptions, compute-related metrics found in O-RAN specifications, and the need for interaction between O-RAN and IETF control planes.
- Discussion addressed concerns about IETF picking sides among RAN technologies and the expertise within CATS on O-RAN. Authors confirmed relevant O-RAN expertise within their group.
- The importance of formal liaison with O-RAN for defining metrics and expressing needs was highlighted. A specific requirement for CATS to interact with external systems (like O-RAN control planes) was identified.
Metrics Draft Scope:
- A key decision point was presented: whether the Metrics draft should focus only on computing metrics (Choice A) or cover all CATS-relevant metrics (compute, networking, storage, energy) (Choice B).
- The co-authors indicated a strong preference for Choice B, arguing that a broader scope is necessary for the derivation of higher-level normalized metrics used in service instance selection (e.g., IO speed, energy metrics). This was generally supported.
Overall WG Progress & Future Work:
- An open question was raised about the roadmap for future contributions beyond the three core WG documents (Use Cases, Metrics, Framework).
- Chairs indicated that once the current three adopted documents stabilize, the WG would look further into technological aspects, such as mechanisms for distributing metrics, implications of metric change rates, and the reuse or adaptation of existing control and data plane tools, as outlined in the charter.
- WG participants were encouraged to review and contribute to existing drafts to enable progress on new items.

Decisions and Action Items

Decision: Metrics Draft Scope
- The CATS Metrics draft will cover all CATS-relevant metrics, including compute, networking, storage, and energy, to facilitate the derivation of normalized metrics for service instance selection.
Action Item (General to all Use Case Authors):
- All authors who presented use cases: Review the existing CATS Use Cases and Requirements draft (specifically sections 4 and 5). Propose concise text edits, focusing on core points and new specific requirements, to the mailing list for integration into the working group document. The responsibility for drafting these contributions lies with the individual draft authors.
Action Item (Green Challenges Use Case - Jin & DK):
- DK: Extract specific cost/energy requirements from the current CATS use case specification and propose text on the mailing list for integration.
- Jin: Consider the discussion points and suggestions for future updates to the green challenges draft.
Action Item (ITS Use Cases - Paul):
- Paul: Propose specific text edits to Section 4.2 (Intelligent Transport Systems) and Section 5 (Requirements) of the WG Use Cases draft to incorporate new ITS-specific requirements identified. The current individual draft can then transition to an applicability statement.
Action Item (Industrial Use Cases - Tu):
- Tu: Summarize the industrial use case and its specific requirements (aim for approximately two pages of text) and propose this content for a new subsection within Section 4 of the WG Use Cases draft. Also, ensure previous comments regarding DetNet overlap are addressed.
Action Item (O-RAN Use Cases - Luis):
- Luis: Extract the specific requirement for CATS to interact with external systems and send this proposed text to the mailing list for discussion.
- Luis: Coordinate with co-author Mark (O-RAN WG N chair) to discuss potential liaison statement (LS) coordination with O-RAN, particularly regarding metrics. Update the WG on the mailing list with progress.
Action Item (Metrics Draft Authors - Kehan et al.):
- Kehan et al.: Address all received comments (from the mailing list and GitHub), with particular attention to metric definitions, representation, and the implications of the agreed-upon broad scope. Align the draft with the other CATS WG documents and carefully design the strategy for metric normalization.
- Kehan et al.: Upload a new version of the Metrics draft before the Bangkok IETF meeting.
Action Item (WG Participants):
- All WG participants: Actively review, comment on, and contribute to the existing CATS working group documents (Use Cases, Metrics, Framework) to ensure their stability and enable the working group to adopt new work items in the future.

Next Steps

Individual use case authors are expected to submit their proposed text changes to the CATS mailing list promptly.
The Metrics draft will be revised and a new version uploaded before the IETF 122 meeting in Bangkok.
Ongoing discussions will continue on the mailing list for all outstanding action items and to prepare for further work on CATS technology, including metric distribution and tool reuse, as the core documents stabilize.
The chairs will follow up on coordination efforts with external organizations like O-RAN.