This draft defines a subcode for the BFD "Cease" message, for "BFD Down." The document is succinct and clearly written, but the security considerations are a bit too succinct, consisting only of the single sentence "This document introduces no additional BGP security considerations." That may well be true (if, say, the subcode is strictly informative and the receiver does not change its behavior on receipt of that subcode), but an additional sentence or two explaining why that's true would be appreciated. A nod to the security considerations in RFC 5880 would probably be appropriate, as well as a mention of whether or not the mechanisms defined in that document are mandatory to implement.