I have reviewed this document as part of the Operational directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be included in AD reviews during the IESG review. Document editors and WG chairs should treat these comments just like any other last call comments. Document: draft-ietf-6man-mtu-option-12 Reviewer: Sheng Jiang Review Date: 2022-02-09 This experimental document specifies a new mechanims to in-boundly discover the minimum Path MTU along the forward path between a source host to a destination host with a newly defined IPv6 Hop-by-Hop option that is used to record . The document is well-writen and reader-friendly. It clearly defines the behaviours on each devices with different roles. This document also have a special section 9 to explain the "experiment goals" of this specification. However, personally, I still not fully understand why this document are intending for "experimental" and what would be the experiment range. It seems for me this mechanism are good enough to be a proposed standard to persuade people use it widely. If by deploying it, issues are found or refining are needed. We can always update it as normal IETF procedure. Summary: Ready Major Concerns: None. Minor Concerns: None. Regards, Sheng