I am the SECDIR reviewer for this document; the security directorate tries to review all documents before they go to the IESG. This content is intended primarily for the SecAD's, anyone else should consider this like other last-call comments. This document is READY. This is a short doument. It defines a way for MPLS routers to indicate that they can handle additional meta-data, "entropy labels" and depth of them, to do traffic routing. The security implications of this are well-discussed.