Reviewer: Derrell Piper Review result: ready with nits 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. This document describes a new version of tracroute designed for multicast. In the multicast environment, traceroute functions in reverse with each router on the path back towards the client adding diagnostic information along the way. This information can be used to diagnose a variety of network problems, including packet loss (congestion) and configuration problems (TTL). The security considerations section discusses a variety of requirements and suggestions for multicast routers and the protocol includes an ADMIN_PROHIB flag which can be used at a border router to prevent multicast traceroute from being able to probe network topology or to perform traffic analysis. This appears to be a useful diagnostic utility and the obvious security concerns seem to have been addressed. nits: page 33, section 9.3 and 9.4 MAY should be capitalized in these two sections. Derrell