Hello,   First of all, my apologies for the tardiness of this review....   I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments. The summary of the review is (almost) Ready With Issues.   This draft defines a flag in the Segment Routing Header that when set will result a copy of the packet being made and forwarded for "telemetry data collection and export." That has tremendous security and privacy implications that are not mentioned at all in the Security Considerations. The Security Considerations just say that there's nothing here beyond those described in . I don't think that's the case.   Maybe I'm completely missing something but this sounds to me like it enables what we used to call "service spy mode" on a router-- take a flow and fork a copy off to someone else. I think there needs to be a lot more discussion of the implications of this.   Again, sorry for the tardiness of this review.   regards,   Dan. -- "The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius