Do not be alarmed. 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 with the intent of improving security requirements and considerations in IETF drafts. Comments 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. Version: 06 Summary: Ready with some non-security/non-privacy nits. Ping mechanisms always give me the heebie-jeebies [1] because of the security concerns associated with them (i.e., DoS, spoofing/hijacking/etc., and unauthorized disclosure). This document specifies an extension to the existing ECHO mechanism in RFC 4379 and it does nothing to address these concerns in fact it increases the concerns wrt DoS. *BUT* it rightly points this increase exposure out in the security considerations section. It provides remediation techniques similar to those specified in RFC 4379: rate limit and validate source against access list. This draft, unlike RFC 4379, does recommend that operators wishing to not disclose their nodes blank the address out in the TLV. This draft also refers to RFC 4379 for additional security considerations. WARNING - questions and nits follow: s3 - 1st paragraph: Relayed Echo Reply “replaces” Echo Reply - does this mean you’re deprecating the use of “Echo Reply”? s4.1: Is the outermost label allowed to be set to 255 to support the “ping” mode or must it always be set to 1, 2, etc. to support “traceroute" mode - as described in RFC 4379 s4.3? I know s5 is just an example but it really looks like this extension is just supposed to be for fault isolation. s4.1 - last paragraph: Does the next initiator put it’s address in the stack before or after the previous initiator? I assume it’s after, but I maybe missed that part? Would be good to state that explicitly. Cheers, spt [1] http://en.wikipedia.org/wiki/Heebie-jeebies_(idiom)