IETF Last Call Review of draft-ietf-tls-svcb-ech-07
review-ietf-tls-svcb-ech-07-opsdir-lc-dunbar-2025-04-09-00

I have reviewed this document as part of the Ops area directorate's ongoing
effort to review all IETF documents being processed by the IESG.  These
comments were written primarily for the benefit of the Ops area directors.
Document editors and WG chairs should treat these comments just like any other
last-call comments.

The draft introduces valuable privacy enhancements but also raises several
deployment challenges.

Mixed SVCB RRSets with and without the “ech” parameter are vulnerable to
downgrade attacks, yet may occur in multi-provider environments or during
staged rollouts. Clear operational guidance is needed to mitigate these risks,
such as prioritizing ECH-capable endpoints using SvcPriority. Deployments
involving CDNs or multi-CDN setups add complexity around coordination of ECH
keys and consistent DNS records, and would benefit from best practice
recommendations.

Additionally, diagnosing ECH failures can be difficult due to the lack of
fallback and visibility. The draft should recommend logging and monitoring
strategies to help operators detect misconfigurations. Key rotation, TTL
management, and rollback procedures are also important but not addressed.

The draft should add an “Operational Considerations” section summarizing these
aspects to improve deployability and manageability.

Best Regards,
Linda Dunbar