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.     draft-ietf-tcpm-1323bis-19 is mostly ready.  Discussion of the possible DoS attacks that could occur from the technique described in section 5.3 should be included in this section and mentioned in the security considerations section as well.   Suppose again that segments: A.1, B.1, C.1, ..., Z.1 have been       sent in sequence and that segment B.1 has been lost.  Furthermore,       suppose delivery of some of C.1, ...  Z.1 is delayed until *after*       the retransmission B.2 arrives at the receiver.  These delayed       segments will be discarded unnecessarily when they do arrive,       since their timestamps are now out of date.     Thank you, Kathleen