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. Document is ready with issues. I think the document has appropriate security considerations. One issue I see in the document is that in the intro it states: "The basic idea is that all ingress RBridges send BUM traffic to a centralized node, which SHOULD be a distribution tree root, using unicast TRILL encapsulation." In section 3 it states : "The centralized node MUST be a distribution tree root." The MUST and SHOULD seem to be at odds here.