This document is well written and seems ready to go. The only security issue I thought of as I read through it (attacking by spoofing a reverse metric) is covered in the Security Considerations section. I found one sentence to be slightly ambiguous, but only very slightly. In Section 3.5: A router MUST advertise a Reverse Metric TLV toward a neighbor only for the operational maintenance window period during which it wants a neighbor to temporarily update its IS-IS metric or Traffic Engineering parameters towards it. It begins to look like it's saying that a router MUST advertise this under certain conditions, and it took me a moment to get that it's actually *limiting* when it should be advertised (the "MUST" applies to the "only" clause). If you think my suggested replacement reads well, you might use it; if not, no problem: A router MUST limit the period during which it advertises a Reverse Metric TLV toward a neighbor only to the operational maintenance window period during which it wants that neighbor to temporarily update its IS-IS metric or Traffic Engineering parameters towards it.