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. It is good to describe the deployment consideration in section 5. However, I think there is an issue that the increamental tracing option will impact other IPv6 extension header processing, e.g. SRH. This is similar to the consideration about PMTU, which has many ways to detect. But it is different. The increamental option is encapsulated in HbH which is the first EH. As the option length expands, the intermedate node may not be able to process other EHs. Typically, SRH is used for TE. This will break the network service. Best, Tianran